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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Aging Neurosci.</journal-id>
<journal-title-group>
<journal-title>Frontiers in Aging Neuroscience</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Aging Neurosci.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">1663-4365</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fnagi.2026.1757306</article-id>
<article-version article-version-type="Version of Record" vocab="NISO-RP-8-2008"/>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Original Research</subject>
</subj-group>
</article-categories>
<title-group>
<article-title>Brain lipidomics for region-specific biomarker discovery in neurodegenerative diseases</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" equal-contrib="yes">
<name>
<surname>Jayaprakash</surname>
<given-names>Jayashankar</given-names>
</name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="author-notes" rid="fn0002"><sup>&#x2020;</sup></xref>
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<contrib contrib-type="author" equal-contrib="yes">
<name>
<surname>Gizaw</surname>
<given-names>Solomon Tebeje</given-names>
</name>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<xref ref-type="author-notes" rid="fn0002"><sup>&#x2020;</sup></xref>
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</contrib>
<contrib contrib-type="author">
<name>
<surname>Gowda</surname>
<given-names>Divyavani</given-names>
</name>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
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<contrib contrib-type="author">
<name>
<surname>Hinou</surname>
<given-names>Hiroshi</given-names>
</name>
<xref ref-type="aff" rid="aff4"><sup>4</sup></xref>
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</contrib>
<contrib contrib-type="author">
<name>
<surname>Nishimura</surname>
<given-names>Shin-Ichiro</given-names>
</name>
<xref ref-type="aff" rid="aff4"><sup>4</sup></xref>
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</contrib>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>Hui</surname>
<given-names>Shu-Ping</given-names>
</name>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
<xref ref-type="corresp" rid="c001"><sup>&#x002A;</sup></xref>
<uri xlink:href="https://loop.frontiersin.org/people/1857171"/>
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</contrib>
<contrib contrib-type="author" corresp="yes">
<name>
<surname>B. Gowda</surname>
<given-names>Siddabasave Gowda</given-names>
</name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
<xref ref-type="corresp" rid="c001"><sup>&#x002A;</sup></xref>
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<aff id="aff1"><label>1</label><institution>Graduate School of Global Food Resources, Hokkaido University</institution>, <city>Sapporo</city>, <country country="jp">Japan</country></aff>
<aff id="aff2"><label>2</label><institution>Department of Medical Biochemistry, School of Medicine, College of Health Sciences, Addis Ababa University</institution>, <city>Addis Ababa</city>, <country country="et">Ethiopia</country></aff>
<aff id="aff3"><label>3</label><institution>Faculty of Health Sciences, Hokkaido University</institution>, <city>Sapporo</city>, <country country="jp">Japan</country></aff>
<aff id="aff4"><label>4</label><institution>Frontier Research Center for Advanced Material and Life Science, Faculty of Advanced Life Science, Hokkaido University</institution>, <city>Sapporo</city>, <country country="jp">Japan</country></aff>
<author-notes>
<corresp id="c001"><label>&#x002A;</label>Correspondence: Shu-Ping Hui, <email xlink:href="mailto:keino@hs.hokudai.ac.jp">keino@hs.hokudai.ac.jp</email>; Siddabasave Gowda B. Gowda, <email xlink:href="mailto:gowda@gfr.hokudai.ac.jp">gowda@gfr.hokudai.ac.jp</email></corresp>
<fn fn-type="equal" id="fn0002">
<label>&#x2020;</label>
<p>These authors have contributed equally to this work</p>
</fn>
</author-notes>
<pub-date publication-format="electronic" date-type="pub" iso-8601-date="2026-02-11">
<day>11</day>
<month>02</month>
<year>2026</year>
</pub-date>
<pub-date publication-format="electronic" date-type="collection">
<year>2026</year>
</pub-date>
<volume>18</volume>
<elocation-id>1757306</elocation-id>
<history>
<date date-type="received">
<day>30</day>
<month>11</month>
<year>2025</year>
</date>
<date date-type="rev-recd">
<day>17</day>
<month>01</month>
<year>2026</year>
</date>
<date date-type="accepted">
<day>26</day>
<month>01</month>
<year>2026</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x00A9; 2026 Jayaprakash, Gizaw, Gowda, Hinou, Nishimura, Hui and B. Gowda.</copyright-statement>
<copyright-year>2026</copyright-year>
<copyright-holder>Jayaprakash, Gizaw, Gowda, Hinou, Nishimura, Hui and B. Gowda</copyright-holder>
<license>
<ali:license_ref start_date="2026-02-11">https://creativecommons.org/licenses/by/4.0/</ali:license_ref>
<license-p>This is an open-access article distributed under the terms of the <ext-link ext-link-type="uri" xlink:href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution License (CC BY)</ext-link>. The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</license-p>
</license>
</permissions>
<abstract>
<sec>
<title>Background</title>
<p>Alzheimer&#x2019;s disease (AD), Parkinson&#x2019;s disease (PD), and Huntington&#x2019;s disease (HD) are progressive neurodegenerative diseases (NDs) characterized by chronic neuronal loss. The lack of effective treatments highlights the urgent need for reliable lipid biomarkers to enable diagnosis and monitor disease progression. Previous lipidomic investigations of altered lipid metabolism have focused on a single disease type, limiting cross-disease comparisons.</p>
</sec>
<sec>
<title>Methods</title>
<p>We applied the untargeted liquid chromatography-mass spectrometry (LC/MS) technique to profile brain lipidome alterations and to identify disease-specific lipid biomarkers across AD, HD, and PD. Brain tissue samples were collected from four cerebral lobes of healthy volunteers (HV, <italic>n</italic>&#x202F;=&#x202F;24) and patients diagnosed with AD (<italic>n</italic>&#x202F;=&#x202F;24), PD (<italic>n</italic>&#x202F;=&#x202F;24), and HD (<italic>n</italic>&#x202F;=&#x202F;24). All groups include three males and three females, with brain tissues from four cortical regions sacrificed from each individual.</p>
</sec>
<sec>
<title>Results</title>
<p>A total of 243 lipid molecular species spanning five major classes were annotated, revealing distinct disease-specific lipidomic profiles that differentiated HV from the AD, HD, and PD groups via multivariate analysis. Sphingomyelins and oxidized phosphatidylserine [PS (16:1/24:0;O1)] were significantly increased, while lysophosphatidylcholines (LPC 18:2, LPC 17:2) were decreased in the AD group relative to HV. HD exhibited elevated PS (O-17:0/22:6) and &#x03C9;-6 fatty acid esterified cholesteryl esters (CE 18:2, CE 20:4), alongside decreased essential neuronal lipids such as phosphatidylinositols (PI). The PD lipidome alterations closely resembled those of HD, indicating partially overlapping disruptions in brain lipid metabolism. Receiver operating characteristic analysis identified PS (16:1/24:0;O1), PS (O-17:0/22:6), and PI (18:1/18:1) as potential discriminatory biomarkers with strong diagnostic performance. Regional heatmap analysis revealed significant lipid perturbations were observed in the parietal and occipital lobes across all NDs.</p>
</sec>
<sec>
<title>Conclusion</title>
<p>This study provides a comprehensive overview of disease- and region-specific alterations in the brain lipidome of AD, HD, and PD. The identified lipid species-PS (16:1/24:0;O1), PS (O-17:0/22:6), and PI (18:1/18:1)-may serve as promising candidate biomarkers for NDs diagnosis and warrant further mechanistic and longitudinal validation with large data set.</p>
</sec>
</abstract>
<kwd-group>
<kwd>Alzheimer&#x2019;s disease</kwd>
<kwd>Huntington&#x2019;s disease</kwd>
<kwd>lipid biomarkers</kwd>
<kwd>lipidomics</kwd>
<kwd>liquid chromatography</kwd>
<kwd>mass spectrometry</kwd>
<kwd>Parkinson&#x2019;s disease</kwd>
</kwd-group>
<funding-group>
<award-group id="gs1">
<funding-source id="sp1">
<institution-wrap>
<institution>Japan Society for the Promotion of Science KAKENHI</institution>
</institution-wrap>
</funding-source>
<award-id rid="sp1">25K00258</award-id>
</award-group>
<award-group id="gs2">
<funding-source id="sp2">
<institution-wrap>
<institution>JST SPRING</institution>
</institution-wrap>
</funding-source>
<award-id rid="sp2">JPMJSP2119</award-id>
</award-group>
<funding-statement>The author(s) declared that financial support was received for this work and/or its publication. This work was supported by the JST SPRING (Grant No. JPMJSP2119) and the Japan Society for the Promotion of Science KAKENHI (Grant No. 25K00258).</funding-statement>
</funding-group>
<counts>
<fig-count count="6"/>
<table-count count="1"/>
<equation-count count="0"/>
<ref-count count="67"/>
<page-count count="13"/>
<word-count count="8924"/>
</counts>
<custom-meta-group>
<custom-meta>
<meta-name>section-at-acceptance</meta-name>
<meta-value>Neuroinflammation and Neuropathy</meta-value>
</custom-meta>
</custom-meta-group>
</article-meta>
</front>
<body>
<sec sec-type="intro" id="sec1">
<label>1</label>
<title>Introduction</title>
<p>Neurodegenerative diseases (NDs) are chronic and progressive disorders characterized by the selective loss of neurons and associated cellular connections, leading to motor, cognitive, and behavioral impairments (<xref ref-type="bibr" rid="ref34">Lamptey et al., 2022</xref>). Among the most prevalent NDs are Alzheimer&#x2019;s disease (AD), Parkinson&#x2019;s disease (PD), and Huntington&#x2019;s disease (HD), which collectively impose a substantial socio-economic burden on the aging population worldwide (<xref ref-type="bibr" rid="ref19">GBD 2016 Parkinson&#x2019;s Disease Collaborators, 2018</xref>; <xref ref-type="bibr" rid="ref20">GBD 2019 Dementia Forecasting Collaborators, 2022</xref>). AD, the most common cause of dementia in older adults, is marked by progressive memory loss and cognitive decline, accompanied by the accumulation of phosphorylated tau (p-tau) and &#x03B2;-amyloid (A&#x03B2;) proteins (<xref ref-type="bibr" rid="ref4">Bloom, 2014</xref>). PD, the second most common ND after AD, is characterized by degeneration of dopaminergic neurons in the substantia nigra, leading to &#x03B1;-synuclein aggregation and Lewy body formation that contribute to both motor and non-motor symptoms (<xref ref-type="bibr" rid="ref51">Rissardo et al., 2025</xref>). HD, in contrast, results from abnormal expansion of the cytosine-adenine guanine (CAG) trinucleotide repeat in the Huntington gene, producing a mutant huntingtin protein that drives neuronal degeneration in the striatum and cortex (<xref ref-type="bibr" rid="ref63">Yilmaz et al., 2025a</xref>). These disorders typically manifest in mid-to-late life and are often preceded by long preclinical phases during which molecular alterations occur before clinical symptoms appear (<xref ref-type="bibr" rid="ref30">Katsuno et al., 2018</xref>). Despite major research advances, accurate diagnosis of NDs remains challenging, emphasizing the urgent need for reliable and disease-specific biomarkers (<xref ref-type="bibr" rid="ref31">Khoury and Ghossoub, 2019</xref>; <xref ref-type="bibr" rid="ref36">Li and Le, 2020</xref>).</p>
<p>Current diagnostic approaches-such as invasive sampling, fluid-based protein assays, and neuroimaging techniques lack specificity for NDs detection and diagnosis (<xref ref-type="bibr" rid="ref23">Hansson, 2021</xref>; <xref ref-type="bibr" rid="ref56">Selvam and Ayyavoo, 2024</xref>). Lipidomic profiling offers distinct advantages by enabling comprehensive characterization of lipid alterations and identification of novel lipid biomarkers associated with disease onset and progression (<xref ref-type="bibr" rid="ref67">Zhang et al., 2020</xref>). As lipids constitute ~50% of the brain&#x2019;s dry weight, their balanced metabolism is essential for maintaining cell signaling, proliferation, apoptosis, and neurotransmission (<xref ref-type="bibr" rid="ref47">O&#x2019;Brien and Sampson, 1965</xref>; <xref ref-type="bibr" rid="ref25">Hornemann, 2021</xref>). Disruptions in lipid homeostasis have been closely linked to NDs progression (<xref ref-type="bibr" rid="ref40">Martens et al., 2023</xref>; <xref ref-type="bibr" rid="ref15">Feringa et al., 2025</xref>), positioning brain lipids as promising candidates for potential diagnostic and prognostic biomarkers (<xref ref-type="bibr" rid="ref65">Yoon et al., 2022</xref>). Previous liquid chromatography/mass spectrometry (LC/MS)-based lipidomic analyses have revealed elevated levels of glycerophospholipids (GPs) and sphingolipids (SPs) in AD brain tissue (<xref ref-type="bibr" rid="ref53">Sanni et al., 2025</xref>), as well as alterations in triacylglycerol (TG) and lysophosphatidylcholine (LPC) levels in PD and changes in diacylglycerol and monoacylglycerol levels in HD (<xref ref-type="bibr" rid="ref49">Paryani et al., 2024</xref>; <xref ref-type="bibr" rid="ref64">Yilmaz et al., 2025b</xref>). However, these studies largely focused on single neurological conditions, and most were conducted using plasma or cerebrospinal fluid (CSF) samples, limiting insights into region-specific lipidomic alterations within the brain (<xref ref-type="bibr" rid="ref7">Byeon et al., 2021</xref>; <xref ref-type="bibr" rid="ref37">Liu et al., 2021</xref>).</p>
<p>To address these limitations, the present study employed high-performance liquid chromatography coupled with linear trap quadrupole-Orbitrap mass spectrometry (HPLC/LTQ-Orbitrap-MS) to perform a comprehensive lipidomic analysis of brain tissue samples from healthy volunteers (HV) and patients with AD, HD, and PD. The study further examined sex- and region-specific lipid variations, as summarized in <xref ref-type="fig" rid="fig1">Figure 1</xref>.</p>
<fig position="float" id="fig1">
<label>Figure 1</label>
<caption>
<p>Study design for lipidomic analysis of brain tissue samples collected from healthy volunteers (HV) and individuals with Alzheimer&#x2019;s disease (AD), Parkinson&#x2019;s disease (PD), and Huntington&#x2019;s disease (HD). Sample sizes: HV (<italic>n</italic>&#x202F;=&#x202F;24), AD (<italic>n</italic>&#x202F;=&#x202F;24), PD (<italic>n</italic>&#x202F;=&#x202F;24), and HD (<italic>n</italic>&#x202F;=&#x202F;24).</p>
</caption>
<graphic xlink:href="fnagi-18-1757306-g001.tif" mimetype="image" mime-subtype="tiff">
<alt-text content-type="machine-generated">Workflow diagram showing study population groups (HV, AD, PD, HD) leading to analysis of individual brain lobes, lipid extraction from brain tissue, nontargeted lipidomics using LC/MS, data processing with MS-Dial and X-Calibur, and biomarker identification using computational analysis.</alt-text>
</graphic>
</fig>
</sec>
<sec sec-type="materials|methods" id="sec2">
<label>2</label>
<title>Materials and methods</title>
<sec id="sec3">
<label>2.1</label>
<title>Chemicals</title>
<p>High-purity LC/MS-grade solvents, including isopropanol, chloroform, and methanol, were obtained from Wako Pure Chemical Industries, Ltd. (Osaka, Japan). A 1&#x202F;M aqueous solution of ammonium acetate, used as an additive in the LC/MS mobile phase, was purchased from Sigma-Aldrich (St. Louis, MO, United States). Oleic acid-d9 and EquiSPLASH LIPIDOMIX quantitative standard mixture (Lot: 330731-1EA-013) were procured from Avanti Polar Lipids (Alabaster, AL, United States).</p>
</sec>
<sec id="sec4">
<label>2.2</label>
<title>Sample information</title>
<p>Human brain tissue samples from four cerebral lobes were obtained from healthy volunteers (HV, <italic>n</italic>&#x202F;=&#x202F;24) and patients diagnosed with Alzheimer&#x2019;s disease (AD, <italic>n</italic>&#x202F;=&#x202F;24), Parkinson&#x2019;s disease (PD, <italic>n</italic>&#x202F;=&#x202F;24), and Huntington&#x2019;s disease (HD, <italic>n</italic>&#x202F;=&#x202F;24). The samples were provided by the Human Brain and Spinal Fluid Resource Center (HBSFRC), VA West Los Angeles Healthcare Center, Los Angeles, CA 90073, supported by the National Institute of Neurological Disorders and Stroke (NINDS)/National Institute of Mental Health (NIMH), and the National Multiple Sclerosis Society, United States. Ethical approval for this study was obtained from the Institutional Review Board of the Graduate School of Advanced Life Sciences, Hokkaido University (Approval No. 07-01). Four cortical regions&#x2014;frontal, temporal, parietal, and occipital-were dissected from 24 male and female subjects (a total of 96 cerebral lobes), following previously described protocols (<xref ref-type="bibr" rid="ref21">Gizaw, 2015</xref>), and stored at &#x2212;80&#x202F;&#x00B0;C until analysis. Detailed demographic and specimen characteristics, including brain region, sex, autolysis time, and age, are presented in <xref ref-type="table" rid="tab1">Table 1</xref>.</p>
<table-wrap position="float" id="tab1">
<label>Table 1</label>
<caption>
<p>Demographic and clinical characteristics of study participants.</p>
</caption>
<table frame="hsides" rules="groups">
<thead>
<tr>
<th align="left" valign="top" rowspan="2">Condition</th>
<th align="center" valign="top" colspan="4">Tissue samples of the cerebral cortices (<italic>n</italic> =&#x202F;3, all cases)</th>
<th align="center" valign="top" rowspan="2">Age (average years&#x202F;&#x00B1;&#x202F;SD)</th>
<th align="center" valign="top" rowspan="2">Autolysis time (hours&#x202F;&#x00B1;&#x202F;SD)</th>
</tr>
<tr>
<th align="center" valign="top">Frontal</th>
<th align="center" valign="top">Temporal</th>
<th align="center" valign="top">Parietal</th>
<th align="center" valign="top">Occipital</th>
</tr>
</thead>
<tbody>
<tr>
<td align="left" valign="middle" rowspan="2">Healthy volunteer (HV)</td>
<td align="center" valign="middle" colspan="4">Male</td>
<td align="char" valign="middle" char="&#x00B1;">66 &#x00B1; 9.5</td>
<td align="char" valign="middle" char="&#x00B1;">15.7 &#x00B1; 5.6</td>
</tr>
<tr>
<td align="center" valign="middle" colspan="4">Female</td>
<td align="char" valign="middle" char="&#x00B1;">67 &#x00B1; 11</td>
<td align="char" valign="middle" char="&#x00B1;">17.8 &#x00B1; 2.2</td>
</tr>
<tr>
<td align="left" valign="middle" rowspan="2">Alzheimer&#x2019;s disease (AD)</td>
<td align="center" valign="middle" colspan="4">Male</td>
<td align="char" valign="middle" char="&#x00B1;">77 &#x00B1; 2.8</td>
<td align="char" valign="middle" char="&#x00B1;">13.1 &#x00B1; 3.0</td>
</tr>
<tr>
<td align="center" valign="middle" colspan="4">Female</td>
<td align="char" valign="middle" char="&#x00B1;">63 &#x00B1; 16.7</td>
<td align="char" valign="middle" char="&#x00B1;">17.0 &#x00B1; 1.9</td>
</tr>
<tr>
<td align="left" valign="middle" rowspan="2">Parkinson&#x2019;s disease (PD)</td>
<td align="center" valign="middle" colspan="4">Male</td>
<td align="char" valign="middle" char="&#x00B1;">80 &#x00B1; 7</td>
<td align="char" valign="middle" char="&#x00B1;">18.2 &#x00B1; 10.7</td>
</tr>
<tr>
<td align="center" valign="middle" colspan="4">Female</td>
<td align="char" valign="middle" char="&#x00B1;">72 &#x00B1; 8.5</td>
<td align="char" valign="middle" char="&#x00B1;">15.2 &#x00B1; 0.83</td>
</tr>
<tr>
<td align="left" valign="middle" rowspan="2">Huntington&#x2019;s disease (HD)</td>
<td align="center" valign="middle" colspan="4">Male</td>
<td align="char" valign="middle" char="&#x00B1;">54 &#x00B1; 20.5</td>
<td align="char" valign="middle" char="&#x00B1;">11.7 &#x00B1; 4.0</td>
</tr>
<tr>
<td align="center" valign="middle" colspan="4">Female</td>
<td align="char" valign="middle" char="&#x00B1;">72 &#x00B1; 6.8</td>
<td align="char" valign="middle" char="&#x00B1;">11.8 &#x00B1; 3.7</td>
</tr>
</tbody>
</table>
<table-wrap-foot>
<p>SD, standard deviation.</p>
</table-wrap-foot>
</table-wrap>
</sec>
<sec id="sec5">
<label>2.3</label>
<title>Lipid extraction</title>
<p>Brain tissue samples from HV, AD, PD, and HD were subjected to total lipid extraction using a modified Folch method (<xref ref-type="bibr" rid="ref43">Minami et al., 2025</xref>; <xref ref-type="bibr" rid="ref18">Folch et al., 1957</xref>). In brief, 200&#x202F;&#x03BC;L of brain tissue homogenate in PBS (2&#x202F;mg/100&#x202F;&#x03BC;L) was transferred to a 2&#x202F;mL microcentrifuge tube, followed by the addition of 300&#x202F;&#x03BC;L of ice-cold methanol containing 0.01% butylated hydroxytoluene and 100&#x202F;&#x03BC;L of an internal standard (IS) solution consisting of oleic acid-d9 (10&#x202F;&#x03BC;g/mL) and EquiSPLASH LIPIDOMIX mixtures in methanol (1&#x202F;&#x03BC;g/mL). Subsequently, 800&#x202F;&#x03BC;L of chloroform was added, and the mixture was vortexed for 5&#x202F;min and centrifuged at 15,000&#x202F;rpm for 10&#x202F;min to achieve biphasic separation. The lower chloroform phase containing lipids was collected into a new 2&#x202F;mL tube, and the aqueous phase was re-extracted with chloroform under the same conditions. The resulting chloroform extracts were combined and evaporated in a centrifugal evaporator at 4&#x202F;&#x00B0;C for 3&#x202F;h. The dried lipid residues were reconstituted in 100&#x202F;&#x03BC;L of methanol, centrifuged at 15,000&#x202F;rpm for 10&#x202F;min, and the supernatants were analyzed by LC/MS with an injection volume of 20&#x202F;&#x03BC;L per run. Simultaneously, blank and quality control (QC) samples (prepared by mixing multiple brain extracts) were acquired between the runs for data quality management. QC samples were employed to manage inter-batch variability throughout the analysis, and the limit of detection (LOD) for each lipid class was determined by analyzing internal standards prepared at different concentration levels. The determined LOD for the internal standards was in the range of 0.01&#x202F;ng/mL to 1&#x202F;ng/mL.</p>
</sec>
<sec id="sec6">
<label>2.4</label>
<title>LC/MS analysis</title>
<p>Lipidomic analysis was performed using a high-performance liquid chromatography (HPLC) system (Shimadzu Corporation, Kyoto, Japan) coupled to an LTQ Orbitrap XL mass spectrometer (Thermo Fisher Scientific Inc., San Jose, CA, United States). Lipid separation was achieved on an Atlantis T3 C18 column (2.1&#x202F;mm&#x202F;&#x00D7;&#x202F;150&#x202F;mm, 3&#x202F;&#x03BC;m; Waters, Milford, MA, United States) maintained at 40&#x202F;&#x00B0;C, with a flow rate of 0.2&#x202F;mL/min. The mobile phase consisted of 10&#x202F;mM aqueous ammonium acetate (A), isopropanol (B), and methanol (C), using an elution gradient identical to that described in our previous study (<xref ref-type="bibr" rid="ref45">Nath et al., 2024</xref>). All mass spectrometric parameters were consistent with those reported previously (<xref ref-type="bibr" rid="ref28">Jayaprakash et al., 2025</xref>). Data acquisition was performed in both positive and negative electrospray ionization (ESI) modes. In negative mode, the source and capillary voltages were set to 3&#x202F;kV and 10&#x202F;V, respectively, with a scan range of <italic>m</italic>/<italic>z</italic> 160&#x2013;1,900. In positive mode, the corresponding voltages were 4&#x202F;kV and 25&#x202F;V, with a scan range of <italic>m</italic>/<italic>z</italic> 150&#x2013;1,950. In both modes, the sheath and auxiliary nitrogen gas flow rates were 50 and 20&#x202F;units, respectively, and the capillary temperature was maintained at 330&#x202F;&#x00B0;C. Full MS spectra were acquired in Fourier transform mode at a resolving power of 60,000, while MS/MS spectra were obtained in ion trap mode using collision-induced dissociation (CID) at 40&#x202F;V collision energy.</p>
</sec>
<sec id="sec7">
<label>2.5</label>
<title>Lipid identification and quantification</title>
<p>Raw LC/MS data were processed using MS-DIAL software (version 4.9) for lipid peak integration and annotation. MS and MS/MS spectra were further examined in Xcalibur software (version 2.2; Thermo Fisher Scientific, Waltham, MA, United States) to confirm the accurate identification of lipid molecular species and to manually verify peak integration. The relative concentrations of lipid metabolites were determined semi-quantitatively based on the IS added during extraction. Data normalization was performed according to the sample weight used for analysis.</p>
</sec>
<sec id="sec8">
<label>2.6</label>
<title>Statistical analysis</title>
<p>Data visualization was performed using Microsoft Excel 2021, and results were plotted with GraphPad Prism (version 8.0.1). To evaluate data variability, orthogonal partial least squares discriminant analysis (OPLS-DA) was conducted using MetaboAnalyst 6.0. OPLS-DA score plots were generated to assess group separation, and variable importance in projection (VIP) plots were used to identify key discriminatory lipid features. Statistical analyses were performed using ordinary two-way ANOVA followed by Bonferroni&#x2019;s multiple comparison test for pairwise comparisons. Differences were considered statistically significant at <italic>p</italic>&#x202F;&#x003C;&#x202F;0.05. Data are presented as mean &#x00B1; standard error of the mean (SEM).</p>
</sec>
</sec>
<sec sec-type="results" id="sec9">
<label>3</label>
<title>Results</title>
<sec id="sec10">
<label>3.1</label>
<title>Multivariate analysis of the brain lipidome</title>
<p>Untargeted lipidomic profiling was performed on brain tissue samples obtained from the frontal, temporal, parietal, and occipital cortices of HV and patients diagnosed with AD, PD, and HD was conducted using HPLC/LTQ-Orbitrap-MS. The analysis identified 243 distinct lipid molecular species encompassing five major lipid classes, as shown in <xref ref-type="fig" rid="fig2">Figure 2A</xref>. Among these, 40 lipid metabolites were identified as fatty acyls (FAs), followed by 32 phosphatidylethanolamine (PEs), 20 phosphatidylserine (PSs), 15 phosphatidylcholine (PCs), 14 cardiolipin (CLs), 14 phosphatidylglycerol (PGs), 13 phosphatidylinositol (PIs), 13 ceramides (Cer), 13 hexosylceramides (HexCer), 10 TGs, 9 LPCs, 9 acyl-hexosylceramides (AHexCer), among others. The detailed list of each identified lipid molecular species, including their respective retention times and <italic>m</italic>/<italic>z</italic> values, is provided in <xref ref-type="supplementary-material" rid="SM1">Supplementary Table S1</xref>.</p>
<fig position="float" id="fig2">
<label>Figure 2</label>
<caption>
<p><bold>(A)</bold> Distribution of different lipid classes identified across brain regions of HV, AD, HD, and PD. Orthogonal partial least squares discriminant analysis (OPLS-DA) score plots and variable importance in projection (VIP) plots analysis for comparing lipidome profiles in <bold>(B)</bold> HV and AD groups, <bold>(C)</bold> HV and HD groups, <bold>(D)</bold> HV and PD groups.</p>
</caption>
<graphic xlink:href="fnagi-18-1757306-g002.tif" mimetype="image" mime-subtype="tiff">
<alt-text content-type="machine-generated">Panel A shows two bar charts representing the number of identified lipid molecular species by class, with classes and numbers color-coded. Panels B, C, and D each contain two plots: a score plot visualizing group separation based on orthogonal T and T scores, and a variable importance plot (VIP plot) listing key lipid species and their VIP scores, for comparisons between AD vs HV, HD vs HV, and PD vs HV respectively. Each score plot features ellipses around group clusters, and VIP plots include a color scale indicating relative abundance.</alt-text>
</graphic>
</fig>
<p>Multivariate statistical analyses were conducted to elucidate group- and disease-specific differences in brain lipid composition among the HV, AD, PD, and HD groups. OPLS-DA was applied to the lipid molecular profiles obtained from the four cortical regions, and the resulting score and VIP plots are presented in <xref ref-type="fig" rid="fig2">Figures 2B</xref>&#x2013;<xref ref-type="fig" rid="fig2">D</xref>. The OPLS-DA score plot for HV and AD groups demonstrated clear separation, indicating distinct lipidomic signatures (<xref ref-type="fig" rid="fig2">Figure 2B</xref>). The first two components (T score 1 and T score 2) explained 28.1% of the total model variance. The corresponding VIP plot identified key lipid species contributing to group discrimination, including sphingolipids (e.g., SM d18:1/16:0), fatty acids (e.g., FA 13:0), and glycerophospholipids (e.g., LPC 20:4) with VIP scores greater than 2. <xref ref-type="fig" rid="fig2">Figure 2C</xref> illustrates the OPLS-DA score plot showing distinct separation between HV and HD groups, suggesting marked differences in lipid composition. The first two components accounted for 28.2% of the model variance. The associated VIP plot highlighted fatty acids (e.g., FA 18:0) and glycerophospholipids (e.g., PS 18:0/20:3) as major contributors to this separation. Similarly, as shown in <xref ref-type="fig" rid="fig2">Figure 2D</xref>, the OPLS-DA score plot revealed a clear group separation between HV and PD groups, with the model explaining 43% of the total variance, indicating pronounced lipidomic differences. The VIP plot highlighted key lipid species contributing to the group discrimination, belonging to fatty acids (e.g., FA 18:0), glycerophospholipids (PC 18:0/20:4), and sterols (CE 20:4).</p>
</sec>
<sec id="sec11">
<label>3.2</label>
<title>Disease-specific alteration in brain lipidome and identification of biomarkers for AD, PD, and HD</title>
<p>The volcano plots illustrate the distribution of significantly altered lipids between HV and disease groups (AD, HD, and PD) by plotting &#x2212;log<sub>10</sub>(<italic>p</italic>-value) against log<sub>2</sub>(fold change), highlighting lipid species with both statistical significance and substantial fold changes (<xref ref-type="fig" rid="fig3">Figure 3A</xref>). Lipids with significantly higher abundance in disease groups appear in red on the right side of the plot, whereas those with decreased abundance are shown in blue on the left, reflecting disease-specific changes in lipid levels.</p>
<fig position="float" id="fig3">
<label>Figure 3</label>
<caption>
<p><bold>(A)</bold> Volcanic plot representing significantly altered lipids (unpaired <italic>t</italic>-test, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.05) in brain tissue samples comparing <bold>(i)</bold> HV vs. AD, <bold>(ii)</bold> HV vs. HD, and <bold>(iii)</bold> HV vs. PD. <bold>(B)</bold> Violin plots and receiver operating characteristic (ROC) curves analysis for top discriminatory lipid markers: <bold>(i)</bold> PS (16:1/24:0;O1), <bold>(ii)</bold> PS (O-17:0/22:6), and <bold>(iii)</bold> PI (18:1/18:1) across AD, HD, and PD groups. [Ordinary two-way ANOVA with Bonferroni&#x2019;s multiple comparisons test, (95% CI), <sup>#</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001, <sup>&#x002A;&#x002A;&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.001, <sup>&#x002A;&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.01, <sup>&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.05, and 0.1(ns)]. All data are represented as mean&#x202F;&#x00B1;&#x202F;SEM.</p>
</caption>
<graphic xlink:href="fnagi-18-1757306-g003.tif" mimetype="image" mime-subtype="tiff">
<alt-text content-type="machine-generated">Panel A contains three volcano plots comparing metabolite expression between healthy volunteers and Alzheimer&#x2019;s disease (HV vs AD; i), healthy volunteers and Huntington&#x2019;s disease (HV vs HD; ii), and healthy volunteers and Parkinson&#x2019;s disease (HV vs PD; iii), with upregulatedand downregulated metabolites colored by log2 fold change and log10 p-values. Panel B presents violin plots and ROC curves for selected metabolites, displaying group concentration differences and diagnostic performance, witharea under the curve (AUC) values and significance notations.</alt-text>
</graphic>
</fig>
<p>Compared with HV SM (d18:1/16:0), SM (d18:1/18:1), SM (d18:1/16:1), and PS (16:1/24:0;O1) were significantly increased in the AD groups. In contrast, LPC 17:2, LPC 18:2, and FA 22:4;(2OH) were significantly decreased relative to HV (<xref ref-type="fig" rid="fig3">Figure 3Ai</xref>). Comparison of HV and HD groups revealed an increase in several lipid species, including multiple cholesterol esters (CEs), cardiolipins (CLs), PS (18:0/22:4), FA 18:0, FA 20:4;(2OH), PE (O-18:2/22:4), and PS (O-17:0/22:6). Conversely, levels of phosphatidylinositol species-PI (18:0/20:3), PI (18:1/18:1), PI (O-19:0/20:3), PI (20:4/17:1;O1)-and lysophosphatidylinositol species LPI 18:0 and LPI 18:1 were decreased in HD compared with HV (<xref ref-type="fig" rid="fig3">Figure 3Aii</xref>). Similar lipidome alterations were observed in PD, with elevated levels of CEs, FAs, and other lipid species, such as PS (18:1/22:4;O4), CL 78:10, PG (18:0/18:1;O1), and PS (O-17:0/22:6). Decreased levels of HexCer (d18:0/25:0), Cer (d18:1/18:1), PI (20:4/17:1;O1), and PE (18:1/16:1;O2) were detected in PD relative to HV (<xref ref-type="fig" rid="fig3">Figure 3Aiii</xref>). A comprehensive list of the most significantly altered lipids and their fold-change values is provided in <xref ref-type="supplementary-material" rid="SM1">Supplementary Tables S2&#x2013;S4</xref>.</p>
<p>Receiver operating characteristic (ROC) analysis was performed on lipid species exhibiting significant alterations between HV and disease cohorts to evaluate their potential as diagnostic biomarkers. Violin plots illustrating relative lipid concentrations across groups are presented alongside ROC curves to visualize discriminatory performance (<xref ref-type="fig" rid="fig3">Figure 3B</xref>). Among the significantly altered lipids in AD, PS (16:1/24:0;O1) showed notable diagnostic capability, yielding area under the curve (AUC) values of 0.6736 for AD, 0.7240 for HD, and 0.7066 for PD. The violin plot demonstrates a marked increase of this lipid in AD compared with HV, with non-significant differences in HD and PD (<xref ref-type="fig" rid="fig3">Figure 3Bi</xref>). Another key lipid, PS (O-17:0/22:6), exhibited excellent diagnostic performance for HD and PD, with AUCs of 1.000 and 0.9167, respectively, while showing moderate discrimination for AD (AUC = 0.5156). Consistently, PS (O-17:0/22:6) levels were significantly elevated in HD and PD, but unchanged in AD, relative to HV (<xref ref-type="fig" rid="fig3">Figure 3Bii</xref>). Similarly, PI (18:1/18:1) demonstrated strong discriminatory power with AUCs of 0.9722 and 0.9236 for HD and PD, and moderate differentiation for AD (AUC&#x202F;=&#x202F;0.6736). The violin plot revealed significantly reduced PI (18:1/18:1) levels across all three disease groups compared with HV (<xref ref-type="fig" rid="fig3">Figure 3Biii</xref>). Collectively, these findings indicate that PS (16:1/24:0;O1), PS (O-17:0/22:6), and PI (18:1/18:1) may represent promising disease-specific lipid biomarkers for the diagnosis of AD, HD, and PD in older adults.</p>
</sec>
<sec id="sec12">
<label>3.3</label>
<title>Region-specific brain lipidome alterations across AD, PD, and HD</title>
<p>Region-specific spatial distribution of significantly altered lipid species across frontal, temporal, parietal, and occipital regions in HV and patients with AD, PD, and HD is shown in <xref ref-type="fig" rid="fig4">Figure 4</xref>. The results revealed both disease-specific and region-dependent alterations in the levels of PS (16:1/24:0;O1). This lipid was significantly elevated in the AD group, with the greatest increase observed in the occipital cortex (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001) and a modest, non-significant rise in the parietal region, suggesting possible localized oxidation of PS (16:1/24:1) in the occipital and parietal regions of the AD brain. No significant changes were detected in the frontal and temporal regions of AD or in any brain regions of the HD and PD groups relative to HV. The spatial distribution of PS (16:1/24:0;O1) is illustrated in the heatmaps and violin plots in <xref ref-type="fig" rid="fig4">Figure 4A</xref>. A distinct pattern of increased PS (O-17:0/22:6) levels was observed predominantly in the HD and PD groups. In HD, the parietal and occipital cortices showed pronounced increases (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001), followed by moderate elevation in the temporal cortex (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.001) and mild but significant changes in the frontal region (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.01). Similarly, the PD group exhibited a strong increase in the occipital (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001) and parietal (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.001) regions, with non-significant trends in the frontal and temporal cortices. In contrast, the AD group showed no significant regional variation in PS (O-17:0/22:6) abundance. The region-specific distribution of this lipid species is shown in <xref ref-type="fig" rid="fig4">Figure 4B</xref>. Analysis of PI (18:1/18:1) revealed a consistent decrease across all three disease groups compared with HV. In HD, PI (18:1/18:1) levels were markedly reduced in the parietal and occipital regions (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001), moderately decreased in the temporal lobe (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.001), and unchanged in the frontal cortex. In PD, significant reductions were observed in the temporal and parietal regions (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001), accompanied by a mild decrease in the occipital cortex (<italic>p</italic>&#x202F;&#x003C;&#x202F;0.05) but a non-significant difference in the frontal region. The AD group displayed minor, non-significant decreases across all four brain regions. Region-specific heatmaps and violin plots illustrating the distribution of PI (18:1/18:1) are presented in <xref ref-type="fig" rid="fig4">Figure 4C</xref>. Comprehensive violin plots summarizing disease- and region-specific distributions of total PS, oxidized PS (OxPS), ether-linked PS, and PI levels, along with a heatmap of the top 50 region-specific lipid species across HV, AD, HD, and PD groups, are provided in <xref ref-type="supplementary-material" rid="SM1">Supplementary Figures S1, S2</xref>.</p>
<fig position="float" id="fig4">
<label>Figure 4</label>
<caption>
<p>Brain-region heatmaps and violin plots illustrating region-specific distribution of significantly altered lipid species across AD, HD, and PD groups: <bold>(A)</bold> PS (16:1/24:0;O1), <bold>(B)</bold> PS (O-17:0/22:6), <bold>(C)</bold> PI (18:1/18:1). [Ordinary two-way ANOVA with Bonferroni&#x2019;s multiple comparisons test, (95% CI), <sup>#</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001, <sup>&#x002A;&#x002A;&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.001, <sup>&#x002A;&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.01, <sup>&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.05, and 0.1(ns)]. All data are represented as mean&#x202F;&#x00B1;&#x202F;SEM.</p>
</caption>
<graphic xlink:href="fnagi-18-1757306-g004.tif" mimetype="image" mime-subtype="tiff">
<alt-text content-type="machine-generated">Three sets of brain illustrations for Alzheimer&#x2019;s disease (AD), Huntington&#x2019;s disease (HD), and Parkinson&#x2019;s disease (PD) correspond to color-coded maps and violin plots showing regional concentrations of specific lipid species across frontal, temporal, parietal, and occipital lobes. Violin plots compare healthy volunteers (HV), AD, HD, and PD for phosphatidylserine (PS 16:1/24:0;O1 and O-17:0/22:6) and phosphatidylinositol (PI 18:1/18:1), indicating statistical significance among groups. Concentration scales and significance markers are included.</alt-text>
</graphic>
</fig>
</sec>
<sec id="sec13">
<label>3.4</label>
<title>Sex-specific brain lipid fingerprinting across AD, PD, and HD</title>
<p>Sex-dependent variations in brain lipidomic alterations among HV, AD, PD, and HD are presented in <xref ref-type="fig" rid="fig5">Figure 5</xref>. Volcano plots illustrate key sex-specific lipid changes by plotting &#x2212;log<sub>10</sub>(<italic>p</italic>-value) against log<sub>2</sub>(fold change), highlighting lipids with significant sex differences in abundance (<xref ref-type="fig" rid="fig5">Figure 5A</xref>). In the comparison between HV and AD groups, male participants exhibited increased levels of LPE 18:0, LPS 18:0, LPE 16:0, SM (d18:1/16:0), HexCer (d18:1/23:0;O), and decreased levels of LPC 17:2 and LPC 18:2 relative to HV (<xref ref-type="fig" rid="fig5">Figure 5Ai</xref>). In contrast, female AD participants displayed elevated levels of PS (16:1/24:0;O1), SM (d18:1/18:1), and CL 74:8, along with reduced concentrations of several LPCs and other lipids, including FA 22:4;(2OH), TG (18:1/18:1/18:2), and TG (18:0/16:1/18:2), compared with HV (<xref ref-type="fig" rid="fig5">Figure 5Aii</xref>). Among HD participants, males showed increased levels of multiple CEs, CLs, FAs, and PS (O-17:0/22:6), while several PI species, as well as LPG 18:1 and LPI 18:0, were decreased relative to HV (<xref ref-type="fig" rid="fig5">Figure 5Aiii</xref>). Female HD participants exhibited a comparable lipidome profile, characterized by increased levels of CEs, CLs, and FAs, accompanied by elevated PS (O-17:0/22:6) and reduced levels of PI species, including PI (18:1/18:1), PI (18:0/20:3), PI (20:4/17:1;O1), and PI (O-19:0/20:3), compared to HV (<xref ref-type="fig" rid="fig5">Figure 5Aiv</xref>).</p>
<fig position="float" id="fig5">
<label>Figure 5</label>
<caption>
<p><bold>(A)</bold> Volcanic plot representing sex-specific significantly altered lipid levels (unpaired <italic>t</italic>-test, <italic>p</italic>&#x202F;&#x003C;&#x202F;0.05) in the brain samples comparing <bold>(i,ii)</bold> HV vs. AD, <bold>(iii,iv)</bold> HV vs. HD, and <bold>(v,vi)</bold> HV vs. PD from male and female participants. <bold>(B)</bold> Violin plots representing significantly altered lipids in the male and female participants of <bold>(i,ii)</bold> HV vs. AD, <bold>(iii,iv)</bold> HV vs. HD, and <bold>(v,vi)</bold> HV vs. PD. Sample sizes: HV: (12 males and 12 females), AD: (12 males and 12 females), HD: (12 males and 12 females), and PD: (12 males and 12 females). [Ordinary two-way ANOVA with Bonferroni&#x2019;s multiple comparison test, (95% CI), <sup>#</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001, <sup>&#x002A;&#x002A;&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.001, <sup>&#x002A;&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.01, <sup>&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.05, and 0.1(ns)]. All data are represented as mean&#x202F;&#x00B1;&#x202F;SEM.</p>
</caption>
<graphic xlink:href="fnagi-18-1757306-g005.tif" mimetype="image" mime-subtype="tiff">
<alt-text content-type="machine-generated">Figure consisting of two panels. Panel A presents six volcano plots comparing lipid species changes between healthy volunteers versus those with Alzheimer&#x2019;s, Huntington&#x2019;s, or Parkinson&#x2019;s disease, separated by male and female symbols. Each plot uses color gradients indicating log2 fold change, log10 p-values thresholds, and highlights up- and down-regulated lipids. Panel B shows six violin plots comparing concentrations of specific lipid species by sex and disease group, with statistical notations for significance.</alt-text>
</graphic>
</fig>
<p>Similarly, in the PD group, male participants displayed increased levels of PS (O-17:0/22:6), CEs, and FAs, while Cer (d18:1/18:1) and HexCer (d18:0/25:0) were decreased relative to HV (<xref ref-type="fig" rid="fig5">Figure 5Av</xref>). Female PD participants exhibited a similar trend, with elevated PS (O-17:0/22:6), FAs, CEs, and other lipid species, alongside decreased levels of HexCer (d18:0/25:0), PC (18:0/20:4), and other lipids compared with HV (<xref ref-type="fig" rid="fig5">Figure 5Avi</xref>). To further characterize these sex-related differences, violin plots were generated to visualize relative lipid abundances across male and female participants within each group (<xref ref-type="fig" rid="fig5">Figure 5B</xref>). In the AD cohort, PS (16:1/24:0;O1) was significantly elevated in females compared with HV, while no significant difference was observed in males (<xref ref-type="fig" rid="fig5">Figure 5Bi</xref>). Conversely, HexCer (d18:1/23:0;O) was significantly increased in male AD participants but remained unchanged in females (<xref ref-type="fig" rid="fig5">Figure 5Bii</xref>). In the HD group, PI (18:1/18:1) was significantly decreased in both sexes, whereas PS (O-17:0/22:6) was increased in both male and female participants relative to HV (<xref ref-type="fig" rid="fig5">Figures 5Biii,iv</xref>). Similarly, in PD, PS (O-17:0/22:6) levels were significantly elevated across both sexes, while HexCer (d18:0/25:0) concentrations were significantly reduced compared with HV (<xref ref-type="fig" rid="fig5">Figures 5Bv,vi</xref>).</p>
</sec>
</sec>
<sec sec-type="discussion" id="sec14">
<label>4</label>
<title>Discussion</title>
<p>To the best of our knowledge, this study represents the first comprehensive, untargeted brain lipidomic profiling of AD, HD, and PD patients, aimed at identifying potential disease-, region-, and sex-specific biomarkers for NDs diagnosis. Previous studies have shown that as the disease progresses, it will predominantly affect and widespread over other subcortical brain regions in the advanced stage of the disease (<xref ref-type="bibr" rid="ref6">Brettschneider et al., 2015</xref>; <xref ref-type="bibr" rid="ref52">Rowley et al., 2018</xref>; <xref ref-type="bibr" rid="ref24">Holmes et al., 2024</xref>). In this study, we have obtained brain tissues from the patients at the advanced (dementia) stage of AD, PD, and HD, where pathology may extensively spread from subcortical origins into cortical regions across all four lobes: frontal, temporal, parietal, and occipital. Therefore, selecting these four cortical regions for lipidomic profiling is highly relevant for the discovery of disease biomarkers. The lipidomic alterations identified were contextualized using Kyoto Encyclopedia of Genes and Genomes (KEGG) lipid biosynthesis pathway<xref ref-type="fn" rid="fn0001"><sup>1</sup></xref> analysis (<xref ref-type="fig" rid="fig6">Figure 6</xref>) (<xref ref-type="bibr" rid="ref28">Jayaprakash et al., 2025</xref>). Multivariate analysis (<xref ref-type="fig" rid="fig2">Figures 2B</xref>&#x2013;<xref ref-type="fig" rid="fig2">D</xref>) revealed clear separations between HV and each disease group, indicating substantial remodeling of lipid metabolism in these neurodegenerative disorders (<xref ref-type="bibr" rid="ref62">Yang et al., 2022</xref>). The highest explained variance was observed in PD (43%), suggesting pronounced lipidomic heterogeneity, likely due to the selective vulnerability of dopaminergic neurons and mitochondrial lipid dysfunction (<xref ref-type="bibr" rid="ref59">Tkachenko et al., 2025</xref>). FAs are essential for brain development, neurogenesis, and neurotransmitter synthesis (<xref ref-type="bibr" rid="ref66">Youdim et al., 2000</xref>). In this study, FAs levels were significantly elevated in both HD and PD groups (<xref ref-type="fig" rid="fig6">Figure 6</xref>), consistent with previous reports describing increased FAs in HD plasma and PD CSF samples (<xref ref-type="bibr" rid="ref41">McGarry et al., 2020</xref>; <xref ref-type="bibr" rid="ref17">Fern&#x00E1;ndez-Irigoyen et al., 2021</xref>). Specifically, elevated stearic acid (FA 18:0) in HD and PD brains (<xref ref-type="fig" rid="fig3">Figure 3A</xref>) may reflect reduced n9-desaturase activity, leading to impaired membrane fluidity and disrupted neuronal signaling, particularly within the frontal cortex of PD brains (<xref ref-type="bibr" rid="ref12">Fabelo et al., 2011</xref>). Furthermore, saturated long-chain fatty acids, including FA 18:0 and myristic acid (FA 14:0) were increased in both the sex groups of HD and PD brains (<xref ref-type="fig" rid="fig5">Figure 5</xref>), indicating <italic>de novo</italic> fatty acid synthesis is closely associated with inflammatory cell subsets, which drive inflammation in both the sex groups of HD and PD (<xref ref-type="bibr" rid="ref5">Bogie et al., 2020</xref>).</p>
<fig position="float" id="fig6">
<label>Figure 6</label>
<caption>
<p>Lipid mapping of brain lipidome alterations in HV, AD, HD, and PD groups using biosynthesis pathway analysis. Data are shown as mean&#x202F;&#x00B1;&#x202F;SEM (<italic>y</italic>-axis: lipid subclass concentration in ng/mg; <italic>x</italic>-axis: HV vs. AD, HD, and PD). Acetyl CoA, acetyl coenzyme A; FAs, fatty acids; DHAP, dihydroxyacetone phosphate; G3P, glycerol-3-phosphate; LPA, lysophosphatidic acid; PA, phosphatidic acid; CDP-DAG, cytidine diphosphate diacylglycerol; PI, phosphatidylinositol; PE, phosphatidylethanolamine; LPE, lyso-phosphatidylethanolamine; PC, phosphatidylcholine; LPC, lyso-phosphatidylcholine; PS, phosphatidylserine; DAG, diacylglycerol; TG, triacylglycerol; Ser, serine; Cer, ceramide; HexCer, hexosylceramide; AHexCer, acylhexosylceramide; SM, sphingomyelin. [Ordinary two-way ANOVA with Bonferroni&#x2019;s multiple comparison test, (95% CI), <sup>#</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.0001, <sup>&#x002A;&#x002A;&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.001, <sup>&#x002A;&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.01, <sup>&#x002A;</sup><italic>p</italic>&#x202F;&#x003C;&#x202F;0.05, and 0.1(ns)].</p>
</caption>
<graphic xlink:href="fnagi-18-1757306-g006.tif" mimetype="image" mime-subtype="tiff">
<alt-text content-type="machine-generated">Metabolic pathway diagram illustrating lipid metabolism with molecules such as Acyl-CoA, dihydrosphingosine, palmitoyl-CoA, and others, each linked to bar graphs comparing lipid levels across HV, AD, HD, and PD groups. Bars for each group are color-coded, and statistical significance is indicated on the graphs. Pathway arrows illustrate relationships between lipid types including fatty acids, ceramides, phospholipids, and others, accompanied by abbreviations and intermediate metabolites.</alt-text>
</graphic>
</fig>
<p>GPs are critical regulators of neuronal membrane stability and cell proliferation (<xref ref-type="bibr" rid="ref46">Nitsch et al., 1991</xref>). Most GPs belonging subclass of lipids exhibited distinct alterations across diseases (<xref ref-type="fig" rid="fig6">Figure 6</xref>). LPC levels were significantly decreased in AD but increased in PD and HD. These results align with earlier findings of reduced LPC in AD brain tissues-implicated in neurotoxicity and inflammation (<xref ref-type="bibr" rid="ref29">Kalia et al., 2023</xref>), and elevated LPC in the PD putamen, likely linked to altered phospholipase A2 activity under neuroinflammatory conditions (<xref ref-type="bibr" rid="ref13">Fanning et al., 2019</xref>; <xref ref-type="bibr" rid="ref61">Wu et al., 2021</xref>). Decrease in LPC levels in AD brains has previously been correlated to amyloid &#x03B2; load (<xref ref-type="bibr" rid="ref22">Grimm et al., 2011</xref>).</p>
<p>Our study further found that the observed decrease in LPC levels was predominated by females (<xref ref-type="fig" rid="fig5">Figure 5A</xref>). These results are consistent with previous findings on decreased LPC in 3xTg-AD female mouse brain, indicating an increase in lysophospholipid acyltransferase activity (<xref ref-type="bibr" rid="ref57">Strefeler et al., 2023</xref>).</p>
<p>PS lipids also participate in numerous neuronal signaling pathways (<xref ref-type="bibr" rid="ref38">Ma et al., 2022</xref>). Elevated PS levels in PD frontal cortex promote &#x03B1;-synuclein aggregation on phospholipid membranes, driving neuronal degeneration (<xref ref-type="bibr" rid="ref12">Fabelo et al., 2011</xref>; <xref ref-type="bibr" rid="ref8">Canerina-Amaro et al., 2019</xref>). This pattern was reflected in our PD and HD results (<xref ref-type="fig" rid="fig6">Figure 6</xref>).</p>
<p>Oxidized forms of PS (OxPS), such as PS (16:0/24:1;O1), were elevated in the occipital and parietal cortices of AD brains, while ether-linked PS species [PS (O-17:0/22:6)] were increased in the temporal, parietal, and occipital regions of HD and PD brains (<xref ref-type="fig" rid="fig4">Figures 4A</xref>,<xref ref-type="fig" rid="fig4">B</xref>). These region-specific changes suggest ongoing neuroinflammatory processes and support their potential role as spatially defined biomarkers (<xref ref-type="bibr" rid="ref54">Santos et al., 2024</xref>). Iron accumulation and lipid peroxidation are associated with the development of neurological disorders through the cystine/glutamate antiporter (System X<sub>c</sub><sup>&#x2212;</sup>), glutathione peroxidase 4 (GPX4), and glutathione (GSH) (System X<sub>c</sub><sup>&#x2212;</sup>/GSH/GPX4 axis) (<xref ref-type="bibr" rid="ref35">Li et al., 2020</xref>). Elevated lipid oxidation serves as a key driver of ferroptosis in AD brain tissues-an iron-dependent form of regulated cell death characterized by the accumulation of phospholipid hydroperoxides (<xref ref-type="bibr" rid="ref48">O&#x2019;Donnell and Bochkov, 2025</xref>). This process leads to the functional impairment of GPX4, the primary enzyme responsible for reducing oxidized lipids via GPH (<xref ref-type="bibr" rid="ref55">Seiler et al., 2008</xref>). A recent postmortem study reported reduced GPX4 expression levels in the vicinity of amyloid plaques in AD brains (<xref ref-type="bibr" rid="ref39">Majern&#x00ED;kov&#x00E1; et al., 2024</xref>). In parallel, mitochondrial dysfunction (including small mitochondria with increased mitochondrial membrane densities, vanishing mitochondria Crista, and outer mitochondria memberane rupture) has been increasingly recognized as a crucial contributor to AD pathogenesis, exacerbating synaptic deficits, adenosine triphosphate (ATP) depletion, and oxidative stress through enhanced lipid peroxidation (<xref ref-type="bibr" rid="ref44">Misrani et al., 2021</xref>; <xref ref-type="bibr" rid="ref42">McGill Percy et al., 2025</xref>). Elevated reactive oxygen species (ROS) generation in the aging brain further intensifies oxidative lipid damage in AD (<xref ref-type="bibr" rid="ref3">Alkhalifa et al., 2025</xref>). Additionally, increased ROS levels and ATP depletion have been observed in the plasma of AD patients, reflecting systemic oxidative imbalance (<xref ref-type="bibr" rid="ref2">Ademowo et al., 2020</xref>). Collectively, these findings suggest that the observed increase in PS (16:0/24:1;O1) levels may result from GPX4 deficiency and excessive ROS production, particularly in females and within the occipital region of the AD brain.</p>
<p>The biological function of ether-PS species in HD and PD remains poorly understood and warrants further investigation. PIs are crucial regulators of neuronal cell signaling (<xref ref-type="bibr" rid="ref9">Chun and Chung, 2020</xref>). Previous studies have documented decreased PI levels in the cerebral cortex of animal models of AD, PD, and HD (<xref ref-type="bibr" rid="ref60">Waugh, 2015</xref>), which is consistent with the reductions observed here (<xref ref-type="fig" rid="fig6">Figure 6</xref>). This may indicate disrupted phosphoinositide signaling and its associated phosphatidylinositol phosphates biosynthesis, which are essential lipids for neuronal function (<xref ref-type="bibr" rid="ref9">Chun and Chung, 2020</xref>). Specifically, PI (18:1/18:1) is recognized as a protective lipokine that supports neuronal survival. Its consistent decline across all brain regions in AD, PD, and HD (<xref ref-type="fig" rid="fig4">Figure 4C</xref>) suggests loss of neuroprotective capacity and increased susceptibility to oxidative stress and programmed cell death (<xref ref-type="bibr" rid="ref58">Th&#x00FC;rmer et al., 2022</xref>), reinforcing its value as a potential biomarker. Furthermore, PI(18:1/18:1) levels showed a significant decrease in HD brains across both sexes (<xref ref-type="fig" rid="fig5">Figure 5B</xref>), indicating that dysregulation of PI metabolism may contribute to synaptic plasticity impairment during HD progression (<xref ref-type="bibr" rid="ref14">Farzana et al., 2023</xref>).</p>
<p>SPs are integral to neuronal membrane composition and intercellular signaling (<xref ref-type="bibr" rid="ref10">Crivelli et al., 2020</xref>). Dysregulation of SPs metabolism has been implicated in the pathogenesis of multiple NDs (<xref ref-type="bibr" rid="ref27">Hussain et al., 2019</xref>). Previous studies reported elevated sphingomyelin (SM) levels in the CSF and hippocampus of AD patients (<xref ref-type="bibr" rid="ref33">Kosicek et al., 2012</xref>; <xref ref-type="bibr" rid="ref26">Hsiao et al., 2013</xref>), in agreement with our findings (<xref ref-type="fig" rid="fig6">Figure 6</xref>). Further, these levels were increased in both the sex groups of AD patients (<xref ref-type="fig" rid="fig5">Figure 5</xref>). Increased SM may indicate overexpression of sphingomyelin synthase 1, which correlates with A&#x03B2; accumulation (<xref ref-type="bibr" rid="ref26">Hsiao et al., 2013</xref>). Conversely, the observed reductions in Cer and HexCer species, particularly in male PD brains (<xref ref-type="fig" rid="fig5">Figure 5</xref>), may arise from downregulation of ceramide synthase-1, which contributes to PD pathogenesis (<xref ref-type="bibr" rid="ref1">Abbott et al., 2014</xref>). Further, CEs play key roles in amyloidogenesis (<xref ref-type="bibr" rid="ref11">Di Paolo and Kim, 2011</xref>), and excessive accumulation of CEs has been epidemiologically associated with increased dementia risk (<xref ref-type="bibr" rid="ref16">Feringa and van der Kant, 2021</xref>). In this study, &#x03C9;-6 fatty acid esterified CE accumulation was evident in HD and PD brain tissues (<xref ref-type="fig" rid="fig6">Figure 6</xref>), consistent with previous reports in the caudate and putamen regions of the HD brain (<xref ref-type="bibr" rid="ref50">Phillips et al., 2020</xref>), suggesting upregulation of acyl-coenzyme A: cholesterol acyltransferase 1 may correlate with increased CEs in ND patients (<xref ref-type="bibr" rid="ref32">Kim et al., 2011</xref>). The observed increase in CEs levels was evident in both the sex groups of HD and PD brain tissues; however, the exact sex-specific CE metabolism still needs further research (<xref ref-type="fig" rid="fig5">Figure 5</xref>).</p>
<p>Overall, this study provides novel insights into brain lipidome profiles across AD, PD, and HD, identifying 243 lipid molecular species. Multivariate analyses revealed distinct group separations between HV and disease groups. ROC analysis further identified PS (16:1/24:0;O1), PS (O-17:0/22:6), and PI (18:1/18:1) as promising diagnostic biomarker candidates for AD, HD, and PD, respectively. Regional analysis indicated that the occipital and parietal cortices are most affected across these disorders. Despite these advances, several limitations should be acknowledged. First, the study relied on semi-quantitative lipidomic data. Second, the relatively small sample size limits the statistical robustness of the specific findings. Third, the lack of control for potential major confounding factors such as diet, physical activity, chronic medication history, genetic background, and post-mortem interval (PMI) may influence the observed lipidome changes. ROC analysis was conducted using the discovery set; however, the absence of replication and validation in independent cohorts represents a key limitation. Validation in an external cohort, ideally using plasma or CSF samples from living patients, is essential to confirm the reproducibility of the present findings and to establish their potential clinical utility. This study is limited to only four cortical regions across control and AD, HD, and PD individuals. Future studies should incorporate primary disease epicenters to delineate lipidomic alterations during early pathological stages in disease progression. There is a general acceptance that aberrant misfolding and non-physiological aggregation of A&#x03B2; in AD, &#x03B1;- synuclein in PD, and huntingtin protein in HD damage the brain and eventually lead to neuronal loss. As a result, the overall observed lipid alterations may reflect both intrinsic metabolic reprogramming and secondary changes in cellular composition (e.g., neuronal loss, gliosis), which warrants future cellular lipidomic studies to validate the identified lipid biomarkers. Mechanistic linkages between the observed lipid dysregulation and neurodegenerative pathology remain to be fully elucidated.</p>
<p>In summary, this study constitutes the first comparative lipidomic investigation of AD, HD, and PD brain tissues using untargeted lipidomics, revealing disease-specific lipid alterations and identifying PS (16:1/24:0;O1), PS (O-17:0/22:6), and PI (18:1/18:1) as potential lipid biomarkers. These findings advance our understanding of lipid metabolism in neurodegeneration and underscore the need for future mechanistic and longitudinal studies to validate these biomarkers and clarify their roles in disease progression.</p>
</sec>
</body>
<back>
<sec sec-type="data-availability" id="sec15">
<title>Data availability statement</title>
<p>The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/<xref ref-type="supplementary-material" rid="SM1">Supplementary material</xref>.</p>
</sec>
<sec sec-type="ethics-statement" id="sec16">
<title>Ethics statement</title>
<p>The studies involving humans were approved by Graduate School of Advanced Life Sciences, Hokkaido University (Approval No. 07-01). The studies were conducted in accordance with the local legislation and institutional requirements. The participants provided their written informed consent to participate in this study.</p>
</sec>
<sec sec-type="author-contributions" id="sec17">
<title>Author contributions</title>
<p>JJ: Validation, Writing &#x2013; original draft, Data curation, Visualization, Formal analysis, Software. STG: Writing &#x2013; review &#x0026; editing, Project administration, Data curation, Conceptualization, Methodology. DG: Data curation, Writing &#x2013; review &#x0026; editing, Visualization. HH: Resources, Writing &#x2013; review &#x0026; editing. S-IN: Resources, Writing &#x2013; review &#x0026; editing. S-PH: Resources, Writing &#x2013; review &#x0026; editing. SGBG: Visualization, Resources, Funding acquisition, Project administration, Methodology, Conceptualization, Writing &#x2013; review &#x0026; editing, Supervision.</p>
</sec>
<ack>
<title>Acknowledgments</title>
<p>The authors would like to acknowledge the resources provided by the Human Brain and Spinal Fluid Resource Center (HBSFRC), the National Institute of Neurological Disorders and Stroke (NINDS), the National Institute of Mental Health (NIMH), and the National Multiple Sclerosis Society.</p>
</ack>
<sec sec-type="COI-statement" id="sec18">
<title>Conflict of interest</title>
<p>The author(s) declared that this work was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
<sec sec-type="ai-statement" id="sec19">
<title>Generative AI statement</title>
<p>The author(s) declared that Generative AI was not used in the creation of this manuscript.</p>
<p>Any alternative text (alt text) provided alongside figures in this article has been generated by Frontiers with the support of artificial intelligence and reasonable efforts have been made to ensure accuracy, including review by the authors wherever possible. If you identify any issues, please contact us.</p>
</sec>
<sec sec-type="disclaimer" id="sec20">
<title>Publisher&#x2019;s note</title>
<p>All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.</p>
</sec>
<sec sec-type="supplementary-material" id="sec21">
<title>Supplementary material</title>
<p>The Supplementary material for this article can be found online at: <ext-link xlink:href="https://www.frontiersin.org/articles/10.3389/fnagi.2026.1757306/full#supplementary-material" ext-link-type="uri">https://www.frontiersin.org/articles/10.3389/fnagi.2026.1757306/full#supplementary-material</ext-link></p>
<supplementary-material xlink:href="Table_1.XLSX" id="SM1" mimetype="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" xmlns:xlink="http://www.w3.org/1999/xlink"><label>SUPPLEMENTARY TABLE S1</label><caption><p>Relative concentration (ng/mg) of quantified lipids in brain samples.</p></caption></supplementary-material>
<supplementary-material xlink:href="Table_1.XLSX" id="SM2" mimetype="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" xmlns:xlink="http://www.w3.org/1999/xlink"><label>SUPPLEMENTARY TABLE S2</label><caption><p>Top altered lipid molecular species between HV and AD groups of brain tissue samples (Unpaired t-test, <italic>p</italic> &#x003C;0.05).</p></caption></supplementary-material>
<supplementary-material xlink:href="Table_1.XLSX" id="SM3" mimetype="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" xmlns:xlink="http://www.w3.org/1999/xlink"><label>SUPPLEMENTARY TABLE S3</label><caption><p>Top altered lipid molecular species between HV and HD groups of brain tissue samples (Unpaired t-test, <italic>p</italic> &#x003C;0.05).</p></caption></supplementary-material>
<supplementary-material xlink:href="Table_1.XLSX" id="SM4" mimetype="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" xmlns:xlink="http://www.w3.org/1999/xlink"><label>SUPPLEMENTARY TABLE S4</label><caption><p>Top altered lipid molecular species between HV and PD groups of brain tissue samples (Unpaired t-test, <italic>p</italic> &#x003C;0.05).</p></caption></supplementary-material>
<supplementary-material xlink:href="Table_1.XLSX" id="SM5" mimetype="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" xmlns:xlink="http://www.w3.org/1999/xlink"><label>SUPPLEMENTARY FIGURE S1</label><caption><p>Violin plots of disease-specific and region-specific alterations in lipid classes between HV and disease groups (AD, HD, and PD) in A. Total PS, B. Total oxidized PS, C. Total ether-PS, and D. Total PI. (Ordinary two-way ANOVA with Bonferroni&#x2019;s multiple comparison test, (95% CI), #<italic>p</italic>&#x003C; 0.0001, &#x002A;&#x002A;&#x002A;<italic>p</italic>&#x003C;0.001, &#x002A;&#x002A;<italic>p</italic>&#x003C;0.01, &#x002A;<italic>p</italic>&#x003C;0.05, 0.1(ns)). Data = mean &#x00B1; SEM.</p></caption></supplementary-material>
<supplementary-material xlink:href="Table_1.XLSX" id="SM6" mimetype="application/vnd.openxmlformats-officedocument.spreadsheetml.sheet" xmlns:xlink="http://www.w3.org/1999/xlink"><label>SUPPLEMENTARY FIGURE S2</label><caption><p>Heatmaps of the top 50 altered lipids across frontal (F), temporal (T), parietal (P), and occipital (O) regions of A. HV and AD, B. HV and HD, and C. HV and PD. Red = higher concentration; blue = lower concentration. (Abbreviation: HV: Healthy volunteers, AD: Alzheimer&#x2019;s Disease, HD: Huntington&#x2019;s Disease, and PD: Parkinson&#x2019;s Disease).</p></caption></supplementary-material>
</sec>
<ref-list>
<title>References</title>
<ref id="ref1"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Abbott</surname><given-names>S. K.</given-names></name> <name><surname>Li</surname><given-names>H.</given-names></name> <name><surname>Mu&#x00F1;oz</surname><given-names>S. S.</given-names></name> <name><surname>Knoch</surname><given-names>B.</given-names></name> <name><surname>Batterham</surname><given-names>M.</given-names></name> <name><surname>Murphy</surname><given-names>K. E.</given-names></name> <etal/></person-group>. (<year>2014</year>). <article-title>Altered ceramide acyl chain length and ceramide synthase gene expression in Parkinson&#x2019;s disease</article-title>. <source>Mov. Disord.</source> <volume>29</volume>, <fpage>518</fpage>&#x2013;<lpage>526</lpage>. doi: <pub-id pub-id-type="doi">10.1002/mds.25729</pub-id>, <pub-id pub-id-type="pmid">24822250</pub-id></mixed-citation></ref>
<ref id="ref2"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Ademowo</surname><given-names>O. S.</given-names></name> <name><surname>Dias</surname><given-names>I. H. K.</given-names></name> <name><surname>Diaz-Sanchez</surname><given-names>L.</given-names></name> <name><surname>Sanchez-Aranguren</surname><given-names>L.</given-names></name> <name><surname>Stahl</surname><given-names>W.</given-names></name> <name><surname>Griffiths</surname><given-names>H. R.</given-names></name></person-group> (<year>2020</year>). <article-title>Partial mitigation of oxidized phospholipid-mediated mitochondrial dysfunction in neuronal cells by oxocarotenoids</article-title>. <source>J. Alzheimers Dis.</source> <volume>74</volume>, <fpage>113</fpage>&#x2013;<lpage>126</lpage>. doi: <pub-id pub-id-type="doi">10.3233/JAD-190923</pub-id>, <pub-id pub-id-type="pmid">31985464</pub-id></mixed-citation></ref>
<ref id="ref3"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Alkhalifa</surname><given-names>A.</given-names></name> <name><surname>Alkhalifa</surname><given-names>O.</given-names></name> <name><surname>Durdanovic</surname><given-names>I.</given-names></name> <name><surname>Ibrahim</surname><given-names>D. R.</given-names></name> <name><surname>Maragkou</surname><given-names>S.</given-names></name></person-group> (<year>2025</year>). <article-title>Oxidative stress and mitochondrial dysfunction in Alzheimer&#x2019;s disease: insights into pathophysiology and treatment</article-title>. <source>J. Dement. Alzheimers Dis.</source> <volume>2</volume>:<fpage>17</fpage>. doi: <pub-id pub-id-type="doi">10.3390/jdad2020017</pub-id></mixed-citation></ref>
<ref id="ref4"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Bloom</surname><given-names>G. S.</given-names></name></person-group> (<year>2014</year>). <article-title>Amyloid-&#x03B2; and tau: the trigger and bullet in Alzheimer disease pathogenesis</article-title>. <source>JAMA Neurol.</source> <volume>71</volume>, <fpage>505</fpage>&#x2013;<lpage>508</lpage>. doi: <pub-id pub-id-type="doi">10.1001/jamaneurol.2013.5847</pub-id>, <pub-id pub-id-type="pmid">24493463</pub-id></mixed-citation></ref>
<ref id="ref5"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Bogie</surname><given-names>J. F. J.</given-names></name> <name><surname>Haidar</surname><given-names>M.</given-names></name> <name><surname>Kooij</surname><given-names>G.</given-names></name> <name><surname>Hendriks</surname><given-names>J. J. A.</given-names></name></person-group> (<year>2020</year>). <article-title>Fatty acid metabolism in the progression and resolution of CNS disorders</article-title>. <source>Adv. Drug Deliv. Rev.</source> <volume>159</volume>, <fpage>198</fpage>&#x2013;<lpage>213</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.addr.2020.01.004</pub-id>, <pub-id pub-id-type="pmid">31987838</pub-id></mixed-citation></ref>
<ref id="ref6"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Brettschneider</surname><given-names>J.</given-names></name> <name><surname>Del Tredici</surname><given-names>K.</given-names></name> <name><surname>Lee</surname><given-names>V. M.-Y.</given-names></name> <name><surname>Trojanowski</surname><given-names>J. Q.</given-names></name></person-group> (<year>2015</year>). <article-title>Spreading of pathology in neurodegenerative diseases: a focus on human studies</article-title>. <source>Nat. Rev. Neurosci.</source> <volume>16</volume>, <fpage>109</fpage>&#x2013;<lpage>120</lpage>. doi: <pub-id pub-id-type="doi">10.1038/nrn3887</pub-id>, <pub-id pub-id-type="pmid">25588378</pub-id></mixed-citation></ref>
<ref id="ref7"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Byeon</surname><given-names>S. K.</given-names></name> <name><surname>Madugundu</surname><given-names>A. K.</given-names></name> <name><surname>Jain</surname><given-names>A. P.</given-names></name> <name><surname>Bhat</surname><given-names>F. A.</given-names></name> <name><surname>Jung</surname><given-names>J. H.</given-names></name> <name><surname>Renuse</surname><given-names>S.</given-names></name> <etal/></person-group>. (<year>2021</year>). <article-title>Cerebrospinal fluid lipidomics for biomarkers of Alzheimer&#x2019;s disease</article-title>. <source>Mol. Omics</source> <volume>17</volume>, <fpage>454</fpage>&#x2013;<lpage>463</lpage>. doi: <pub-id pub-id-type="doi">10.1039/d0mo00186d</pub-id>, <pub-id pub-id-type="pmid">34125126</pub-id></mixed-citation></ref>
<ref id="ref8"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Canerina-Amaro</surname><given-names>A.</given-names></name> <name><surname>Pereda</surname><given-names>D.</given-names></name> <name><surname>Diaz</surname><given-names>M.</given-names></name> <name><surname>Rodriguez-Barreto</surname><given-names>D.</given-names></name> <name><surname>Casa&#x00F1;as-S&#x00E1;nchez</surname><given-names>V.</given-names></name> <name><surname>Heffer</surname><given-names>M.</given-names></name> <etal/></person-group>. (<year>2019</year>). <article-title>Differential aggregation and phosphorylation of alpha synuclein in membrane compartments associated with Parkinson disease</article-title>. <source>Front. Neurosci.</source> <volume>13</volume>:<fpage>382</fpage>. doi: <pub-id pub-id-type="doi">10.3389/fnins.2019.00382</pub-id>, <pub-id pub-id-type="pmid">31068782</pub-id></mixed-citation></ref>
<ref id="ref9"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Chun</surname><given-names>Y. S.</given-names></name> <name><surname>Chung</surname><given-names>S.</given-names></name></person-group> (<year>2020</year>). <article-title>High-cholesterol diet decreases the level of phosphatidylinositol 4,5-bisphosphate by enhancing the expression of phospholipase C (PLC&#x03B2;1) in rat brain</article-title>. <source>Int. J. Mol. Sci.</source> <volume>21</volume>:<fpage>1161</fpage>. doi: <pub-id pub-id-type="doi">10.3390/ijms21031161</pub-id>, <pub-id pub-id-type="pmid">32050555</pub-id></mixed-citation></ref>
<ref id="ref10"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Crivelli</surname><given-names>S. M.</given-names></name> <name><surname>Giovagnoni</surname><given-names>C.</given-names></name> <name><surname>Visseren</surname><given-names>L.</given-names></name> <name><surname>Scheithauer</surname><given-names>A.-L.</given-names></name> <name><surname>de Wit</surname><given-names>N.</given-names></name> <name><surname>den Hoedt</surname><given-names>S.</given-names></name> <etal/></person-group>. (<year>2020</year>). <article-title>Sphingolipids in Alzheimer&#x2019;s disease, how can we target them?</article-title> <source>Adv. Drug Deliv. Rev.</source> <volume>159</volume>, <fpage>214</fpage>&#x2013;<lpage>231</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.addr.2019.12.003</pub-id>, <pub-id pub-id-type="pmid">31911096</pub-id></mixed-citation></ref>
<ref id="ref11"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Di Paolo</surname><given-names>G.</given-names></name> <name><surname>Kim</surname><given-names>T. W.</given-names></name></person-group> (<year>2011</year>). <article-title>Linking lipids to Alzheimer&#x2019;s disease: cholesterol and beyond</article-title>. <source>Nat. Rev. Neurosci.</source> <volume>12</volume>, <fpage>284</fpage>&#x2013;<lpage>296</lpage>. doi: <pub-id pub-id-type="doi">10.1038/nrn3012</pub-id>, <pub-id pub-id-type="pmid">21448224</pub-id></mixed-citation></ref>
<ref id="ref12"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Fabelo</surname><given-names>N.</given-names></name> <name><surname>Mart&#x00ED;n</surname><given-names>V.</given-names></name> <name><surname>Santpere</surname><given-names>G.</given-names></name> <name><surname>Mar&#x00ED;n</surname><given-names>R.</given-names></name> <name><surname>Torrent</surname><given-names>L.</given-names></name> <name><surname>Ferrer</surname><given-names>I.</given-names></name> <etal/></person-group>. (<year>2011</year>). <article-title>Severe alterations in lipid composition of frontal cortex lipid rafts from Parkinson&#x2019;s disease and incidental Parkinson&#x2019;s disease</article-title>. <source>Mol. Med.</source> <volume>17</volume>, <fpage>1107</fpage>&#x2013;<lpage>1118</lpage>. doi: <pub-id pub-id-type="doi">10.2119/molmed.2011.00119</pub-id>, <pub-id pub-id-type="pmid">21717034</pub-id></mixed-citation></ref>
<ref id="ref13"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Fanning</surname><given-names>S.</given-names></name> <name><surname>Haque</surname><given-names>A.</given-names></name> <name><surname>Imberdis</surname><given-names>T.</given-names></name> <name><surname>Baru</surname><given-names>V.</given-names></name> <name><surname>Barrasa</surname><given-names>M. I.</given-names></name> <name><surname>Nuber</surname><given-names>S.</given-names></name> <etal/></person-group>. (<year>2019</year>). <article-title>Lipidomic analysis of &#x03B1;-synuclein neurotoxicity identifies stearoyl CoA desaturase as a target for Parkinson treatment</article-title>. <source>Mol. Cell</source> <volume>73</volume>, <fpage>1001</fpage>&#x2013;<lpage>1014.e8</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.molcel.2018.11.028</pub-id>, <pub-id pub-id-type="pmid">30527540</pub-id></mixed-citation></ref>
<ref id="ref14"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Farzana</surname><given-names>F.</given-names></name> <name><surname>McConville</surname><given-names>M. J.</given-names></name> <name><surname>Renoir</surname><given-names>T.</given-names></name> <name><surname>Li</surname><given-names>S.</given-names></name> <name><surname>Nie</surname><given-names>S.</given-names></name> <name><surname>Tran</surname><given-names>H.</given-names></name> <etal/></person-group>. (<year>2023</year>). <article-title>Longitudinal spatial mapping of lipid metabolites reveals pre-symptomatic changes in the hippocampi of Huntington&#x2019;s disease transgenic mice</article-title>. <source>Neurobiol. Dis.</source> <volume>176</volume>:<fpage>105933</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.nbd.2022.105933</pub-id>, <pub-id pub-id-type="pmid">36436748</pub-id></mixed-citation></ref>
<ref id="ref15"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Feringa</surname><given-names>F. M.</given-names></name> <name><surname>den Koppes- Hertog</surname><given-names>S. J.</given-names></name> <name><surname>Wang</surname><given-names>L. Y.</given-names></name> <name><surname>Derks</surname><given-names>R. J. E.</given-names></name> <name><surname>Kruijff</surname><given-names>I.</given-names></name> <name><surname>Erlebach</surname><given-names>L.</given-names></name> <etal/></person-group>. (<year>2025</year>). <article-title>The neurolipid atlas: a lipidomics resource for neurodegenerative diseases</article-title>. <source>Nat. Metab.</source> <volume>7</volume>, <fpage>2142</fpage>&#x2013;<lpage>2164</lpage>. doi: <pub-id pub-id-type="doi">10.1038/s42255-025-01365-z</pub-id>, <pub-id pub-id-type="pmid">40983680</pub-id></mixed-citation></ref>
<ref id="ref16"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Feringa</surname><given-names>F. M.</given-names></name> <name><surname>van der Kant</surname><given-names>R.</given-names></name></person-group> (<year>2021</year>). <article-title>Cholesterol and Alzheimer&#x2019;s disease; from risk genes to pathological effects</article-title>. <source>Front. Aging Neurosci.</source> <volume>13</volume>:<fpage>690372</fpage>. doi: <pub-id pub-id-type="doi">10.3389/fnagi.2021.690372</pub-id>, <pub-id pub-id-type="pmid">34248607</pub-id></mixed-citation></ref>
<ref id="ref17"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Fern&#x00E1;ndez-Irigoyen</surname><given-names>J.</given-names></name> <name><surname>Cartas-Cejudo</surname><given-names>P.</given-names></name> <name><surname>Iruarrizaga-Lejarreta</surname><given-names>M.</given-names></name> <name><surname>Santamar&#x00ED;a</surname><given-names>E.</given-names></name></person-group> (<year>2021</year>). <article-title>Alteration in the cerebrospinal fluid lipidome in Parkinson&#x2019;s disease: a post-mortem pilot study</article-title>. <source>Biomedicine</source> <volume>9</volume>:<fpage>491</fpage>. doi: <pub-id pub-id-type="doi">10.3390/biomedicines9050491</pub-id>, <pub-id pub-id-type="pmid">33946950</pub-id></mixed-citation></ref>
<ref id="ref18"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Folch</surname><given-names>J.</given-names></name> <name><surname>Lees</surname><given-names>M.</given-names></name> <name><surname>Sloane Stanley</surname><given-names>G. H.</given-names></name></person-group> (<year>1957</year>). <article-title>A simple method for the isolation and purification of total lipides from animal tissues</article-title>. <source>J. Biol. Chem.</source> <volume>226</volume>, <fpage>497</fpage>&#x2013;<lpage>509</lpage>. doi: <pub-id pub-id-type="doi">10.1016/s0021-9258(18)64849-5</pub-id>, <pub-id pub-id-type="pmid">13428781</pub-id></mixed-citation></ref>
<ref id="ref19"><mixed-citation publication-type="journal"><person-group person-group-type="author"><collab id="coll1">GBD 2016 Parkinson&#x2019;s Disease Collaborators</collab></person-group> (<year>2018</year>). <article-title>Global, regional, and national burden of Parkinson&#x2019;s disease, 1990&#x2013;2016: a systematic analysis for the Global Burden of Disease Study 2016</article-title>. <source>Lancet Neurol.</source> <volume>17</volume>, <fpage>939</fpage>&#x2013;<lpage>953</lpage>. doi: <pub-id pub-id-type="doi">10.1016/S1474-4422(18)30295-3</pub-id>, <pub-id pub-id-type="pmid">30287051</pub-id></mixed-citation></ref>
<ref id="ref20"><mixed-citation publication-type="journal"><person-group person-group-type="author"><collab id="coll2">GBD 2019 Dementia Forecasting Collaborators</collab></person-group> (<year>2022</year>). <article-title>Estimation of the global prevalence of dementia in 2019 and forecasted prevalence in 2050: an analysis for the Global Burden of Disease Study 2019</article-title>. <source>Lancet Public Health</source> <volume>7</volume>, <fpage>e105</fpage>&#x2013;<lpage>e125</lpage>. doi: <pub-id pub-id-type="doi">10.1016/S2468-2667(21)00249-8</pub-id>, <pub-id pub-id-type="pmid">34998485</pub-id></mixed-citation></ref>
<ref id="ref21"><mixed-citation publication-type="book"><person-group person-group-type="author"><name><surname>Gizaw</surname><given-names>S. T.</given-names></name></person-group> (<year>2015</year>). &#x201C;<article-title>Comprehensive glycomics for the discovery of new biomarkers in neurodegenerative diseases</article-title>&#x201D; in <source>Doctoral Dissertation</source> (<publisher-loc>Sapporo</publisher-loc>: <publisher-name>Hokkaido University Graduate School of Life Sciences</publisher-name>).</mixed-citation></ref>
<ref id="ref22"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Grimm</surname><given-names>M. O. W.</given-names></name> <name><surname>Gr&#x00F6;sgen</surname><given-names>S.</given-names></name> <name><surname>Riemenschneider</surname><given-names>M.</given-names></name> <name><surname>Tanila</surname><given-names>H.</given-names></name> <name><surname>Grimm</surname><given-names>H. S.</given-names></name> <name><surname>Hartmann</surname><given-names>T.</given-names></name></person-group> (<year>2011</year>). <article-title>From brain to food: analysis of phosphatidylcholins, lyso-phosphatidylcholins and phosphatidylcholin-plasmalogens derivates in Alzheimer&#x2019;s disease human post mortem brains and mice model via mass spectrometry</article-title>. <source>J. Chromatogr. A</source> <volume>1218</volume>, <fpage>7713</fpage>&#x2013;<lpage>7722</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.chroma.2011.07.073</pub-id>, <pub-id pub-id-type="pmid">21872257</pub-id></mixed-citation></ref>
<ref id="ref23"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hansson</surname><given-names>O.</given-names></name></person-group> (<year>2021</year>). <article-title>Biomarkers for neurodegenerative diseases</article-title>. <source>Nat. Med.</source> <volume>27</volume>, <fpage>954</fpage>&#x2013;<lpage>963</lpage>. doi: <pub-id pub-id-type="doi">10.1038/s41591-021-01382-x</pub-id>, <pub-id pub-id-type="pmid">34083813</pub-id></mixed-citation></ref>
<ref id="ref24"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Holmes</surname><given-names>S. E.</given-names></name> <name><surname>Honhar</surname><given-names>P.</given-names></name> <name><surname>Tinaz</surname><given-names>S.</given-names></name> <name><surname>Naganawa</surname><given-names>M.</given-names></name> <name><surname>Hilmer</surname><given-names>A. T.</given-names></name> <name><surname>Gallezot</surname><given-names>J.-D.</given-names></name> <etal/></person-group>. (<year>2024</year>). <article-title>Synaptic loss and its association with symptom severity in Parkinson&#x2019;s disease</article-title>. <source>npj Parkinsons Dis.</source> <volume>10</volume>:<fpage>42</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41531-024-00655-9</pub-id>, <pub-id pub-id-type="pmid">38402233</pub-id></mixed-citation></ref>
<ref id="ref25"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hornemann</surname><given-names>T.</given-names></name></person-group> (<year>2021</year>). <article-title>Mini review: lipids in peripheral nerve disorders</article-title>. <source>Neurosci. Lett.</source> <volume>740</volume>:<fpage>135455</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.neulet.2020.135455</pub-id>, <pub-id pub-id-type="pmid">33166639</pub-id></mixed-citation></ref>
<ref id="ref26"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hsiao</surname><given-names>J.-H. T.</given-names></name> <name><surname>Fu</surname><given-names>Y.</given-names></name> <name><surname>Hill</surname><given-names>A. F.</given-names></name> <name><surname>Halliday</surname><given-names>G. M.</given-names></name> <name><surname>Kim</surname><given-names>W. S.</given-names></name></person-group> (<year>2013</year>). <article-title>Elevation in sphingomyelin synthase activity is associated with increases in amyloid-beta peptide generation</article-title>. <source>PLoS One</source> <volume>8</volume>:<fpage>e74016</fpage>. doi: <pub-id pub-id-type="doi">10.1371/journal.pone.0074016</pub-id>, <pub-id pub-id-type="pmid">23977395</pub-id></mixed-citation></ref>
<ref id="ref27"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Hussain</surname><given-names>G.</given-names></name> <name><surname>Wang</surname><given-names>J.</given-names></name> <name><surname>Rasul</surname><given-names>A.</given-names></name> <name><surname>Anwar</surname><given-names>H.</given-names></name> <name><surname>Imran</surname><given-names>A.</given-names></name> <name><surname>Qasim</surname><given-names>M.</given-names></name> <etal/></person-group>. (<year>2019</year>). <article-title>Role of cholesterol and sphingolipids in brain development and neurological diseases</article-title>. <source>Lipids Health Dis.</source> <volume>18</volume>:<fpage>26</fpage>. doi: <pub-id pub-id-type="doi">10.1186/s12944-019-0965-z</pub-id>, <pub-id pub-id-type="pmid">30683111</pub-id></mixed-citation></ref>
<ref id="ref28"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Jayaprakash</surname><given-names>J.</given-names></name> <name><surname>Gowda</surname><given-names>S. G. B.</given-names></name> <name><surname>Gowda</surname><given-names>D.</given-names></name> <name><surname>Ikeda</surname><given-names>A.</given-names></name> <name><surname>Bamai</surname><given-names>Y. A.</given-names></name> <name><surname>Ketema</surname><given-names>R. M.</given-names></name> <etal/></person-group>. (<year>2025</year>). <article-title>Plasma lipidomics of preadolescent children: a Hokkaido study</article-title>. <source>J. Lipids</source> <volume>2025</volume>:<fpage>3106145</fpage>. doi: <pub-id pub-id-type="doi">10.1155/jl/3106145</pub-id>, <pub-id pub-id-type="pmid">40084067</pub-id></mixed-citation></ref>
<ref id="ref29"><mixed-citation publication-type="other"><person-group person-group-type="author"><name><surname>Kalia</surname><given-names>V.</given-names></name> <name><surname>Reyes-Dumeyer</surname><given-names>D.</given-names></name> <name><surname>Dubey</surname><given-names>S.</given-names></name> <name><surname>Nandakumar</surname><given-names>R.</given-names></name> <name><surname>Lee</surname><given-names>A. J.</given-names></name> <name><surname>Lantigua</surname><given-names>R.</given-names></name> <etal/></person-group>. (<year>2023</year>). <article-title>Lysophosphatidylcholines are associated with P-tau181 levels in early stages of Alzheimer&#x2019;s disease</article-title>. <italic>medRxiv</italic>. Available online at: <ext-link xlink:href="https://doi.org/10.1101/2023.08.24.23294581" ext-link-type="uri">https://doi.org/10.1101/2023.08.24.23294581</ext-link>. [Epub ahead of preprint]</mixed-citation></ref>
<ref id="ref30"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Katsuno</surname><given-names>M.</given-names></name> <name><surname>Sahashi</surname><given-names>K.</given-names></name> <name><surname>Iguchi</surname><given-names>Y.</given-names></name> <name><surname>Hashizume</surname><given-names>A.</given-names></name></person-group> (<year>2018</year>). <article-title>Preclinical progression of neurodegenerative diseases</article-title>. <source>Nagoya J. Med. Sci.</source> <volume>80</volume>, <fpage>289</fpage>&#x2013;<lpage>298</lpage>. doi: <pub-id pub-id-type="doi">10.18999/nagjms.80.3.289</pub-id>, <pub-id pub-id-type="pmid">30214078</pub-id></mixed-citation></ref>
<ref id="ref31"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Khoury</surname><given-names>R.</given-names></name> <name><surname>Ghossoub</surname><given-names>E.</given-names></name></person-group> (<year>2019</year>). <article-title>Diagnostic biomarkers of Alzheimer&#x2019;s disease: a state-of-the-art review</article-title>. <source>Biomark. Neuropsychiatry</source> <volume>1</volume>:<fpage>100005</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.bionps.2019.100005</pub-id></mixed-citation></ref>
<ref id="ref32"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Kim</surname><given-names>J.-H.</given-names></name> <name><surname>Ee</surname><given-names>S.-M.</given-names></name> <name><surname>Jittiwat</surname><given-names>J.</given-names></name> <name><surname>Ong</surname><given-names>E.-S.</given-names></name> <name><surname>Farooqui</surname><given-names>A. A.</given-names></name> <name><surname>Jenner</surname><given-names>A. M.</given-names></name> <etal/></person-group>. (<year>2011</year>). <article-title>Increased expression of acyl-coenzyme a: cholesterol acyltransferase-1 and elevated cholesteryl esters in the hippocampus after excitotoxic injury</article-title>. <source>Neuroscience</source> <volume>185</volume>, <fpage>125</fpage>&#x2013;<lpage>134</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.neuroscience.2011.04.018</pub-id>, <pub-id pub-id-type="pmid">21514367</pub-id></mixed-citation></ref>
<ref id="ref33"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Kosicek</surname><given-names>M.</given-names></name> <name><surname>Zetterberg</surname><given-names>H.</given-names></name> <name><surname>Andreasen</surname><given-names>N.</given-names></name> <name><surname>Peter-Katalinic</surname><given-names>J.</given-names></name> <name><surname>Hecimovic</surname><given-names>S.</given-names></name></person-group> (<year>2012</year>). <article-title>Elevated cerebrospinal fluid sphingomyelin levels in prodromal Alzheimer&#x2019;s disease</article-title>. <source>Neurosci. Lett.</source> <volume>516</volume>, <fpage>302</fpage>&#x2013;<lpage>305</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.neulet.2012.04.019</pub-id>, <pub-id pub-id-type="pmid">22521584</pub-id></mixed-citation></ref>
<ref id="ref34"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Lamptey</surname><given-names>R. N. L.</given-names></name> <name><surname>Chaulagain</surname><given-names>B.</given-names></name> <name><surname>Trivedi</surname><given-names>R.</given-names></name> <name><surname>Gothwal</surname><given-names>A.</given-names></name> <name><surname>Layek</surname><given-names>B.</given-names></name> <name><surname>Singh</surname><given-names>J.</given-names></name></person-group> (<year>2022</year>). <article-title>A review of the common neurodegenerative disorders: current therapeutic approaches and the potential role of nanotherapeutics</article-title>. <source>Int. J. Mol. Sci.</source> <volume>23</volume>:<fpage>1851</fpage>. doi: <pub-id pub-id-type="doi">10.3390/ijms23031851</pub-id>, <pub-id pub-id-type="pmid">35163773</pub-id></mixed-citation></ref>
<ref id="ref35"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Li</surname><given-names>J.</given-names></name> <name><surname>Cao</surname><given-names>F.</given-names></name> <name><surname>Yin</surname><given-names>H.-L.</given-names></name> <name><surname>Huang</surname><given-names>Z.-J.</given-names></name> <name><surname>Lin</surname><given-names>Z.-T.</given-names></name> <name><surname>Mao</surname><given-names>N.</given-names></name> <etal/></person-group>. (<year>2020</year>). <article-title>Ferroptosis: past, present and future</article-title>. <source>Cell Death Dis.</source> <volume>11</volume>:<fpage>88</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41419-020-2298-2</pub-id>, <pub-id pub-id-type="pmid">32015325</pub-id></mixed-citation></ref>
<ref id="ref36"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Li</surname><given-names>T.</given-names></name> <name><surname>Le</surname><given-names>W.</given-names></name></person-group> (<year>2020</year>). <article-title>Biomarkers for Parkinson&#x2019;s disease: how good are they?</article-title> <source>Neurosci. Bull.</source> <volume>36</volume>, <fpage>183</fpage>&#x2013;<lpage>194</lpage>. doi: <pub-id pub-id-type="doi">10.1007/s12264-019-00433-1</pub-id>, <pub-id pub-id-type="pmid">31646434</pub-id></mixed-citation></ref>
<ref id="ref37"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Liu</surname><given-names>Y.</given-names></name> <name><surname>Thalamuthu</surname><given-names>A.</given-names></name> <name><surname>Mather</surname><given-names>K. A.</given-names></name> <name><surname>Crawford</surname><given-names>J.</given-names></name> <name><surname>Ulanova</surname><given-names>M.</given-names></name> <name><surname>Wong</surname><given-names>M. W. K.</given-names></name> <etal/></person-group>. (<year>2021</year>). <article-title>Plasma lipidome is dysregulated in Alzheimer&#x2019;s disease and is associated with disease risk genes</article-title>. <source>Transl. Psychiatry</source> <volume>11</volume>:<fpage>344</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41398-021-01362-2</pub-id>, <pub-id pub-id-type="pmid">34092785</pub-id></mixed-citation></ref>
<ref id="ref38"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Ma</surname><given-names>X.</given-names></name> <name><surname>Li</surname><given-names>X.</given-names></name> <name><surname>Wang</surname><given-names>W.</given-names></name> <name><surname>Zhang</surname><given-names>M.</given-names></name> <name><surname>Yang</surname><given-names>B.</given-names></name> <name><surname>Miao</surname><given-names>Z.</given-names></name></person-group> (<year>2022</year>). <article-title>Phosphatidylserine, inflammation, and central nervous system diseases</article-title>. <source>Front. Aging Neurosci.</source> <volume>14</volume>:<fpage>975176</fpage>. doi: <pub-id pub-id-type="doi">10.3389/fnagi.2022.975176</pub-id>, <pub-id pub-id-type="pmid">35992593</pub-id></mixed-citation></ref>
<ref id="ref39"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Majern&#x00ED;kov&#x00E1;</surname><given-names>N.</given-names></name> <name><surname>Marmolejo-Garza</surname><given-names>A.</given-names></name> <name><surname>Salinas</surname><given-names>C. S.</given-names></name> <name><surname>Luu</surname><given-names>M. D. A.</given-names></name> <name><surname>Zhang</surname><given-names>Y.</given-names></name> <name><surname>Trombetta-Lima</surname><given-names>M.</given-names></name> <etal/></person-group>. (<year>2024</year>). <article-title>The link between amyloid &#x03B2; and ferroptosis pathway in Alzheimer&#x2019;s disease progression</article-title>. <source>Cell Death Dis.</source> <volume>15</volume>:<fpage>782</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41419-024-07152-0</pub-id>, <pub-id pub-id-type="pmid">39468028</pub-id></mixed-citation></ref>
<ref id="ref40"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Martens</surname><given-names>G. A.</given-names></name> <name><surname>Ge&#x00DF;ner</surname><given-names>C.</given-names></name> <name><surname>Folkow</surname><given-names>L. P.</given-names></name> <name><surname>Creydt</surname><given-names>M.</given-names></name> <name><surname>Fischer</surname><given-names>M.</given-names></name> <name><surname>Burmester</surname><given-names>T.</given-names></name></person-group> (<year>2023</year>). <article-title>The roles of brain lipids and polar metabolites in the hypoxia tolerance of deep-diving pinnipeds</article-title>. <source>J. Exp. Biol.</source> <volume>226</volume>:<fpage>jeb245355</fpage>. doi: <pub-id pub-id-type="doi">10.1242/jeb.245355</pub-id>, <pub-id pub-id-type="pmid">36970764</pub-id></mixed-citation></ref>
<ref id="ref41"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>McGarry</surname><given-names>A.</given-names></name> <name><surname>Gaughan</surname><given-names>J.</given-names></name> <name><surname>Hackmyer</surname><given-names>C.</given-names></name> <name><surname>Lovett</surname><given-names>J.</given-names></name> <name><surname>Khadeer</surname><given-names>M.</given-names></name> <name><surname>Shaikh</surname><given-names>H.</given-names></name> <etal/></person-group>. (<year>2020</year>). <article-title>Cross-sectional analysis of plasma and CSF metabolomic markers in Huntington&#x2019;s disease for participants of varying functional disability: a pilot study</article-title>. <source>Sci. Rep.</source> <volume>10</volume>:<fpage>20490</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41598-020-77526-9</pub-id>, <pub-id pub-id-type="pmid">33235276</pub-id></mixed-citation></ref>
<ref id="ref42"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>McGill Percy</surname><given-names>K. C.</given-names></name> <name><surname>Liu</surname><given-names>Z.</given-names></name> <name><surname>Qi</surname><given-names>X.</given-names></name></person-group> (<year>2025</year>). <article-title>Mitochondrial dysfunction in Alzheimer&#x2019;s disease: guiding the path to targeted therapies</article-title>. <source>Neurotherapeutics</source> <volume>22</volume>:<fpage>e00525</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.neurot.2025.e00525</pub-id>, <pub-id pub-id-type="pmid">39827052</pub-id></mixed-citation></ref>
<ref id="ref43"><mixed-citation publication-type="other"><person-group person-group-type="author"><name><surname>Minami</surname><given-names>Y.</given-names></name> <name><surname>Gowda</surname><given-names>S. G. B.</given-names></name> <name><surname>Gowda</surname><given-names>D.</given-names></name> <name><surname>Chiba</surname><given-names>H.</given-names></name> <name><surname>Hui</surname><given-names>S. -P.</given-names></name></person-group> (<year>2025</year>). <article-title>Sex- and Regio-Specific Lipid Profiling of Shishamo and Capelin Fish by Nontargeted Liquid Chromatography/Mass Spectrometry</article-title>. <source>Foods</source>. <volume>15</volume>:<fpage>298</fpage>. doi: <pub-id pub-id-type="doi">10.3390/foods15020298</pub-id></mixed-citation></ref>
<ref id="ref44"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Misrani</surname><given-names>A.</given-names></name> <name><surname>Tabassum</surname><given-names>S.</given-names></name> <name><surname>Yang</surname><given-names>L.</given-names></name></person-group> (<year>2021</year>). <article-title>Mitochondrial dysfunction and oxidative stress in Alzheimer&#x2019;s disease</article-title>. <source>Front. Aging Neurosci.</source> <volume>13</volume>:<fpage>617588</fpage>. doi: <pub-id pub-id-type="doi">10.3389/fnagi.2021.617588</pub-id>, <pub-id pub-id-type="pmid">33679375</pub-id></mixed-citation></ref>
<ref id="ref45"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Nath</surname><given-names>L. R.</given-names></name> <name><surname>Gowda</surname><given-names>S. G. B.</given-names></name> <name><surname>Roberts</surname><given-names>T. H.</given-names></name> <name><surname>Gowda</surname><given-names>D.</given-names></name> <name><surname>Khoddami</surname><given-names>A.</given-names></name> <name><surname>Hui</surname><given-names>S.-P.</given-names></name></person-group> (<year>2024</year>). <article-title>Nontargeted lipidomics of Sorghum grain reveals novel fatty acid esters of hydroxy fatty acids and cultivar differences in lipid profiles</article-title>. <source>J. Agric. Food Chem.</source> <volume>72</volume>, <fpage>20690</fpage>&#x2013;<lpage>20703</lpage>. doi: <pub-id pub-id-type="doi">10.1021/acs.jafc.4c05919</pub-id>, <pub-id pub-id-type="pmid">39230960</pub-id></mixed-citation></ref>
<ref id="ref46"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Nitsch</surname><given-names>R.</given-names></name> <name><surname>Pittas</surname><given-names>A.</given-names></name> <name><surname>Blusztajn</surname><given-names>J. K.</given-names></name> <name><surname>Slack</surname><given-names>B. E.</given-names></name> <name><surname>Growdon</surname><given-names>J. H.</given-names></name> <name><surname>Wurtman</surname><given-names>R. J.</given-names></name></person-group> (<year>1991</year>). <article-title>Alterations of phospholipid metabolites in postmortem brain from patients with Alzheimer&#x2019;s disease</article-title>. <source>Ann. N. Y. Acad. Sci.</source> <volume>640</volume>, <fpage>110</fpage>&#x2013;<lpage>113</lpage>. doi: <pub-id pub-id-type="doi">10.1111/j.1749-6632.1991.tb00200.x</pub-id>, <pub-id pub-id-type="pmid">1663712</pub-id></mixed-citation></ref>
<ref id="ref47"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>O&#x2019;Brien</surname><given-names>J. S.</given-names></name> <name><surname>Sampson</surname><given-names>E. L.</given-names></name></person-group> (<year>1965</year>). <article-title>Lipid composition of the normal human brain: gray matter, white matter, and myelin</article-title>. <source>J. Lipid Res.</source> <volume>6</volume>, <fpage>537</fpage>&#x2013;<lpage>544</lpage>.</mixed-citation></ref>
<ref id="ref48"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>O&#x2019;Donnell</surname><given-names>V. B.</given-names></name> <name><surname>Bochkov</surname><given-names>V.</given-names></name></person-group> (<year>2025</year>). <article-title>Oxidized phospholipids in ferroptosis, immunity and inflammation</article-title>. <source>Redox Biochem. Chem.</source> <volume>14</volume>:<fpage>100061</fpage>. doi: <pub-id pub-id-type="doi">10.1016/j.rbc.2025.100061</pub-id></mixed-citation></ref>
<ref id="ref49"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Paryani</surname><given-names>F.</given-names></name> <name><surname>Kwon</surname><given-names>J.-S.</given-names></name> <name><surname>Ng</surname><given-names>C. W.</given-names></name> <name><surname>Jakubiak</surname><given-names>K.</given-names></name> <name><surname>Madden</surname><given-names>N.</given-names></name> <name><surname>Ofori</surname><given-names>K.</given-names></name> <etal/></person-group>. (<year>2024</year>). <article-title>Multi-omic analysis of Huntington&#x2019;s disease reveals a compensatory astrocyte state</article-title>. <source>Nat. Commun.</source> <volume>15</volume>:<fpage>6742</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41467-024-50626-0</pub-id>, <pub-id pub-id-type="pmid">39112488</pub-id></mixed-citation></ref>
<ref id="ref50"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Phillips</surname><given-names>G. R.</given-names></name> <name><surname>Hancock</surname><given-names>S. E.</given-names></name> <name><surname>Brown</surname><given-names>S. H. J.</given-names></name> <name><surname>Jenner</surname><given-names>A. M.</given-names></name> <name><surname>Kreilaus</surname><given-names>F.</given-names></name> <name><surname>Newell</surname><given-names>K. A.</given-names></name> <etal/></person-group>. (<year>2020</year>). <article-title>Cholesteryl ester levels are elevated in the caudate and putamen of Huntington&#x2019;s disease patients</article-title>. <source>Sci. Rep.</source> <volume>10</volume>:<fpage>20314</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41598-020-76973-8</pub-id>, <pub-id pub-id-type="pmid">33219259</pub-id></mixed-citation></ref>
<ref id="ref51"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Rissardo</surname><given-names>J. P.</given-names></name> <name><surname>Gadelmawla</surname><given-names>A. F.</given-names></name> <name><surname>Khalil</surname><given-names>I.</given-names></name> <name><surname>Abdulgadir</surname><given-names>A.</given-names></name> <name><surname>Bhatti</surname><given-names>K. S.</given-names></name> <name><surname>Fornari Caprara</surname><given-names>A. L.</given-names></name></person-group> (<year>2025</year>). <article-title>Epidemiology of autonomic dysfunction in Parkinson&#x2019;s disease (review)</article-title>. <source>Med. Int.</source> <volume>5</volume>:<fpage>68</fpage>. doi: <pub-id pub-id-type="doi">10.3892/mi.2025.267</pub-id>, <pub-id pub-id-type="pmid">41018272</pub-id></mixed-citation></ref>
<ref id="ref52"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Rowley</surname><given-names>C. D.</given-names></name> <name><surname>Tabrizi</surname><given-names>S. J.</given-names></name> <name><surname>Scahill</surname><given-names>R. I.</given-names></name> <name><surname>Leavitt</surname><given-names>B. R.</given-names></name> <name><surname>Roos</surname><given-names>R. A. C.</given-names></name> <name><surname>Durr</surname><given-names>A.</given-names></name> <etal/></person-group>. (<year>2018</year>). <article-title>Altered intracortical T1-weighted/T2-weighted ratio signal in Huntington&#x2019;s disease</article-title>. <source>Front. Neurosci.</source> <volume>12</volume>:<fpage>805</fpage>. doi: <pub-id pub-id-type="doi">10.3389/fnins.2018.00805</pub-id>, <pub-id pub-id-type="pmid">30455625</pub-id></mixed-citation></ref>
<ref id="ref53"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Sanni</surname><given-names>A.</given-names></name> <name><surname>Bennett</surname><given-names>A. I.</given-names></name> <name><surname>Adeniyi</surname><given-names>M.</given-names></name> <name><surname>Mechref</surname><given-names>Y.</given-names></name></person-group> (<year>2025</year>). <article-title>Dysregulated lipids in Alzheimer&#x2019;s disease: insights into biological pathways through LC-MS/MS analysis of human brain tissues</article-title>. <source>ACS Chem. Neurosci.</source> <volume>16</volume>, <fpage>3694</fpage>&#x2013;<lpage>3712</lpage>. doi: <pub-id pub-id-type="doi">10.1021/acschemneuro.5c00230</pub-id>, <pub-id pub-id-type="pmid">40957103</pub-id></mixed-citation></ref>
<ref id="ref54"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Santos</surname><given-names>M.</given-names></name> <name><surname>Melo</surname><given-names>T.</given-names></name> <name><surname>Maur&#x00ED;cio</surname><given-names>T.</given-names></name> <name><surname>Ferreira</surname><given-names>H.</given-names></name> <name><surname>Domingues</surname><given-names>P.</given-names></name> <name><surname>Domingues</surname><given-names>R.</given-names></name></person-group> (<year>2024</year>). <article-title>The non-enzymatic oxidation of phosphatidylethanolamine and phosphatidylserine and their intriguing roles in inflammation dynamics and diseases</article-title>. <source>FEBS Lett.</source> <volume>598</volume>, <fpage>2174</fpage>&#x2013;<lpage>2189</lpage>. doi: <pub-id pub-id-type="doi">10.1002/1873-3468.14992</pub-id>, <pub-id pub-id-type="pmid">39097985</pub-id></mixed-citation></ref>
<ref id="ref55"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Seiler</surname><given-names>A.</given-names></name> <name><surname>Schneider</surname><given-names>M.</given-names></name> <name><surname>F&#x00F6;rster</surname><given-names>H.</given-names></name> <name><surname>Roth</surname><given-names>S.</given-names></name> <name><surname>Wirth</surname><given-names>E. K.</given-names></name> <name><surname>Culmsee</surname><given-names>C.</given-names></name> <etal/></person-group>. (<year>2008</year>). <article-title>Glutathione peroxidase 4 senses and translates oxidative stress into 12/15-lipoxygenase dependent- and AIF-mediated cell death</article-title>. <source>Cell Metab.</source> <volume>8</volume>, <fpage>237</fpage>&#x2013;<lpage>248</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.cmet.2008.07.005</pub-id>, <pub-id pub-id-type="pmid">18762024</pub-id></mixed-citation></ref>
<ref id="ref56"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Selvam</surname><given-names>S.</given-names></name> <name><surname>Ayyavoo</surname><given-names>V.</given-names></name></person-group> (<year>2024</year>). <article-title>Biomarkers in neurodegenerative diseases: a broad overview</article-title>. <source>Explor. Neuroprot. Ther.</source> <volume>4</volume>, <fpage>119</fpage>&#x2013;<lpage>147</lpage>. doi: <pub-id pub-id-type="doi">10.37349/ent.2024.00075</pub-id></mixed-citation></ref>
<ref id="ref57"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Strefeler</surname><given-names>A.</given-names></name> <name><surname>Jan</surname><given-names>M.</given-names></name> <name><surname>Quadroni</surname><given-names>M.</given-names></name> <name><surname>Teav</surname><given-names>T.</given-names></name> <name><surname>Rosenberg</surname><given-names>N.</given-names></name> <name><surname>Chatton</surname><given-names>J.-Y.</given-names></name> <etal/></person-group>. (<year>2023</year>). <article-title>Molecular insights into sex-specific metabolic alterations in Alzheimer&#x2019;s mouse brain using multi-omics approach</article-title>. <source>Alzheimers Res. Ther.</source> <volume>15</volume>:<fpage>8</fpage>. doi: <pub-id pub-id-type="doi">10.1186/s13195-023-01162-4</pub-id>, <pub-id pub-id-type="pmid">36624525</pub-id></mixed-citation></ref>
<ref id="ref58"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Th&#x00FC;rmer</surname><given-names>M.</given-names></name> <name><surname>Gollowitzer</surname><given-names>A.</given-names></name> <name><surname>Pein</surname><given-names>H.</given-names></name> <name><surname>Neukirch</surname><given-names>K.</given-names></name> <name><surname>Gelmez</surname><given-names>E.</given-names></name> <name><surname>Waltl</surname><given-names>L.</given-names></name> <etal/></person-group>. (<year>2022</year>). <article-title>PI(18:1/18:1) is a SCD1-derived lipokine that limits stress signaling</article-title>. <source>Nat. Commun.</source> <volume>13</volume>:<fpage>2982</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41467-022-30374-9</pub-id>, <pub-id pub-id-type="pmid">35624087</pub-id></mixed-citation></ref>
<ref id="ref59"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Tkachenko</surname><given-names>K.</given-names></name> <name><surname>Gonz&#x00E1;lez-S&#x00E1;iz</surname><given-names>J. M.</given-names></name> <name><surname>Pizarro</surname><given-names>C.</given-names></name></person-group> (<year>2025</year>). <article-title>Untargeted lipidomic reveals potential biomarkers in plasma samples for the discrimination of patients affected by Parkinson&#x2019;s disease</article-title>. <source>Molecules</source> <volume>30</volume>:<fpage>850</fpage>. doi: <pub-id pub-id-type="doi">10.3390/molecules30040850</pub-id>, <pub-id pub-id-type="pmid">40005161</pub-id></mixed-citation></ref>
<ref id="ref60"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Waugh</surname><given-names>M. G.</given-names></name></person-group> (<year>2015</year>). <article-title>PIPs in neurological diseases</article-title>. <source>Biochim. Biophys. Acta</source> <volume>1851</volume>, <fpage>1066</fpage>&#x2013;<lpage>1082</lpage>. doi: <pub-id pub-id-type="doi">10.1016/j.bbalip.2015.02.002</pub-id>, <pub-id pub-id-type="pmid">25680866</pub-id></mixed-citation></ref>
<ref id="ref61"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Wu</surname><given-names>Z.</given-names></name> <name><surname>Wu</surname><given-names>S.</given-names></name> <name><surname>Liang</surname><given-names>T.</given-names></name> <name><surname>Wang</surname><given-names>L.</given-names></name></person-group> (<year>2021</year>). <article-title>Lipoprotein-associated phospholipase A2 is a risk factor for patients with Parkinson&#x2019;s disease</article-title>. <source>Front. Neurosci.</source> <volume>15</volume>:<fpage>633022</fpage>. doi: <pub-id pub-id-type="doi">10.3389/fnins.2021.633022</pub-id>, <pub-id pub-id-type="pmid">33958981</pub-id></mixed-citation></ref>
<ref id="ref62"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Yang</surname><given-names>D.</given-names></name> <name><surname>Wang</surname><given-names>X.</given-names></name> <name><surname>Zhang</surname><given-names>L.</given-names></name> <name><surname>Fang</surname><given-names>Y.</given-names></name> <name><surname>Zheng</surname><given-names>Q.</given-names></name> <name><surname>Liu</surname><given-names>X.</given-names></name> <etal/></person-group>. (<year>2022</year>). <article-title>Lipid metabolism and storage in neuroglia: role in brain development and neurodegenerative diseases</article-title>. <source>Cell Biosci.</source> <volume>12</volume>:<fpage>106</fpage>. doi: <pub-id pub-id-type="doi">10.1186/s13578-022-00828-0</pub-id>, <pub-id pub-id-type="pmid">35831869</pub-id></mixed-citation></ref>
<ref id="ref63"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Yilmaz</surname><given-names>A.</given-names></name> <name><surname>Akyol</surname><given-names>S.</given-names></name> <name><surname>Ashrafi</surname><given-names>N.</given-names></name> <name><surname>Saiyed</surname><given-names>N.</given-names></name> <name><surname>Turkoglu</surname><given-names>O.</given-names></name> <name><surname>Graham</surname><given-names>S. F.</given-names></name></person-group> (<year>2025a</year>). <article-title>Lipidomics of Huntington&#x2019;s disease: a comprehensive review of current status and future directions</article-title>. <source>Metabolites</source> <volume>15</volume>:<fpage>10</fpage>. doi: <pub-id pub-id-type="doi">10.3390/metabo15010010</pub-id>, <pub-id pub-id-type="pmid">39852353</pub-id></mixed-citation></ref>
<ref id="ref64"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Yilmaz</surname><given-names>A.</given-names></name> <name><surname>Ashrafi</surname><given-names>N.</given-names></name> <name><surname>Ashrafi</surname><given-names>R.</given-names></name> <name><surname>Akyol</surname><given-names>S.</given-names></name> <name><surname>Saiyed</surname><given-names>N.</given-names></name> <name><surname>Ker&#x0161;evi&#x010D;i&#x016B;t&#x0117;</surname><given-names>I.</given-names></name> <etal/></person-group>. (<year>2025b</year>). <article-title>Lipid profiling of Parkinson&#x2019;s disease brain highlights disruption in lysophosphatidylcholines, and triacylglycerol metabolism</article-title>. <source>npj Parkinsons Dis.</source> <volume>11</volume>:<fpage>159</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41531-025-01023-x</pub-id>, <pub-id pub-id-type="pmid">40500301</pub-id></mixed-citation></ref>
<ref id="ref65"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Yoon</surname><given-names>J. H.</given-names></name> <name><surname>Seo</surname><given-names>Y.</given-names></name> <name><surname>Jo</surname><given-names>Y. S.</given-names></name> <name><surname>Lee</surname><given-names>S.</given-names></name> <name><surname>Cho</surname><given-names>E.</given-names></name> <name><surname>Cazenave-Gassiot</surname><given-names>A.</given-names></name> <etal/></person-group>. (<year>2022</year>). <article-title>Brain lipidomics: from functional landscape to clinical significance</article-title>. <source>Sci. Adv.</source> <volume>8</volume>:<fpage>eadc9317</fpage>. doi: <pub-id pub-id-type="doi">10.1126/sciadv.adc9317</pub-id>, <pub-id pub-id-type="pmid">36112688</pub-id></mixed-citation></ref>
<ref id="ref66"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Youdim</surname><given-names>K. A.</given-names></name> <name><surname>Martin</surname><given-names>A.</given-names></name> <name><surname>Joseph</surname><given-names>J. A.</given-names></name></person-group> (<year>2000</year>). <article-title>Essential fatty acids and the brain: possible health implications</article-title>. <source>Int. J. Dev. Neurosci.</source> <volume>18</volume>, <fpage>383</fpage>&#x2013;<lpage>399</lpage>. doi: <pub-id pub-id-type="doi">10.1016/s0736-5748(00)00013-7</pub-id>, <pub-id pub-id-type="pmid">10817922</pub-id></mixed-citation></ref>
<ref id="ref67"><mixed-citation publication-type="journal"><person-group person-group-type="author"><name><surname>Zhang</surname><given-names>X.</given-names></name> <name><surname>Liu</surname><given-names>W.</given-names></name> <name><surname>Zan</surname><given-names>J.</given-names></name> <name><surname>Wu</surname><given-names>C.</given-names></name> <name><surname>Tan</surname><given-names>W.</given-names></name></person-group> (<year>2020</year>). <article-title>Untargeted lipidomics reveals progression of early Alzheimer&#x2019;s disease in APP/PS1 transgenic mice</article-title>. <source>Sci. Rep.</source> <volume>10</volume>:<fpage>14509</fpage>. doi: <pub-id pub-id-type="doi">10.1038/s41598-020-71510-z</pub-id>, <pub-id pub-id-type="pmid">32884056</pub-id></mixed-citation></ref>
</ref-list>
<fn-group>
<fn fn-type="custom" custom-type="edited-by" id="fn0003">
<p>Edited by: <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/1134289/overview">Alberto Ouro</ext-link>, Sanitary Research Institute Foundation of Santiago de Compostela, Spain</p>
</fn>
<fn fn-type="custom" custom-type="reviewed-by" id="fn0004">
<p>Reviewed by: <ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/843271/overview">Kenji Nagao</ext-link>, Ajinomoto (Japan), Japan</p>
<p><ext-link ext-link-type="uri" xlink:href="https://loop.frontiersin.org/people/336911/overview">Mirela Ambeskovic</ext-link>, University of Lethbridge, Canada</p>
</fn>
</fn-group>
<fn-group>
<fn id="fn0001"><label>1</label>
<p><ext-link xlink:href="https://www.genome.jp/kegg/pathway.html" ext-link-type="uri">https://www.genome.jp/kegg/pathway.html</ext-link></p>
</fn>
</fn-group>
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</article>