The neurobiological mechanisms of PICH-D involve complex changes in neurotransmitter systems and neurotrophic factors (19). A major factor is the imbalance of monoamine neurotransmitters, such as serotonin, dopamine, and norepinephrine, due to disrupted pathways in the fronto-striatal circuit, a key brain network for emotional regulation. This imbalance impairs mood control (9). Anatomical evidence reveals that serotonergic (5-HT) fibers in this circuit originate primarily from the raphe nuclei and project to the prefrontal cortex and striatum via the medial forebrain bundle, while noradrenergic (NE) fibers arise from the locus coeruleus and innervate limbic structures through the dorsal bundle (20). Hemorrhagic lesions disrupting these monoaminergic pathways result in dysregulation of the dynamic balance between prefrontal cortical regions (responsible for cognitive control) and limbic structures such as the amygdala and hippocampus (mediating emotional responses), creating a “top-down” regulatory decompensation state.

Clinical investigations demonstrate significantly reduced cerebrospinal fluid levels of 5-hydroxyindoleacetic acid (5-HIAA), the primary 5-HT metabolite, in hemorrhagic stroke patients, with this decrease showing negative correlation with depressive symptom severity (21). This monoaminergic dysfunction may stem from multiple interacting mechanisms including peri-hematomal edema-induced inhibition of tryptophan hydroxylase activity, abnormal presynaptic 5-HT reuptake, and astrocytic glutamate-glutamine cycle disturbances.

Emerging evidence highlights decreased serum Brain-Derived Neurotrophic Factor (BDNF) levels as another pivotal mechanism in post-hemorrhagic depression. As a crucial mediator of neuroplasticity, BDNF deficiency correlates strongly with impaired neuronal functionality (22). Molecular studies elucidate that BDNF exerts its effects through TrkB receptor-mediated activation of the PI3K/Akt signaling pathway, which supports both neurogenesis in hippocampal dentate gyrus and structural plasticity of dendritic spines in prefrontal pyramidal neurons (23). Preclinical findings from striatal hemorrhage models reveal concurrent reductions in prefrontal BDNF expression and dendritic spine density at 7 days post-hemorrhage, with these synaptic remodeling deficits significantly associated with prolonged immobility time in forced swim tests - a behavioral marker of depression (24).

Recent investigations have highlighted the reciprocal interactions between neuroinflammatory responses and depression following ICH (25). On one hand, secondary neuroinflammation triggered by ICH serves as a critical pathological foundation for depressive symptoms. During cerebral parenchymal hemorrhage, hemoglobin degradation products (e.g., heme and iron ions) and thrombin activate microglia, driving their polarization toward the pro-inflammatory M1 phenotype (10). Activated M1 microglia subsequently amplify the release of inflammatory mediators, including IL-6 and TNF-α, through the TLR4/NF-κB signaling cascade (26). These cytokines not only induce neuronal apoptosis via activation of caspase-3 pathways but also suppress brain-derived neurotrophic factor (BDNF) synthesis in the hippocampus, impairing neuroplasticity ( Figure 1 ).

Conversely, emerging evidence suggests that depressive states may independently amplify neuroinflammatory processes. Elevated systemic inflammatory markers observed in depressed patients create a self-perpetuating cycle, where chronic inflammation exacerbates depressive symptoms and complicates therapeutic interventions (11). Notably, anti-inflammatory strategies such as low-dose minocycline administration demonstrate dual therapeutic potential. By suppressing microglial activation and attenuating pro-inflammatory cytokine release, minocycline effectively mitigates neuroinflammation (27). This neuroprotective effect not only facilitates neural repair but also improves mood regulation, likely through restoration of neuronal function in emotion-related circuits. Such findings underscore the therapeutic value of targeting neuroimmune interactions in ICH-related depression management.

Structural damage caused by cerebral hemorrhage in specific brain regions (e.g., prefrontal cortex, anterior cingulate cortex, basal ganglia) may impair emotional regulation through dual mechanisms: direct disruption of anatomical integrity in cortico-limbic circuits and secondary neuroplastic adaptations driving functional network reorganization (28). Resting-state functional MRI (rs-fMRI) studies reveal critical insights: patients with depression exhibit significant weakening of functional connectivity between posterior components of the default mode network (DMN, particularly the posterior cingulate cortex) and limbic structures (including amygdala and hippocampus). This functional decoupling demonstrates dose-dependent correlations with the severity of anhedonia (29). Notably, DMN-limbic connectivity strength shows potential as a biomarker for predicting antidepressant treatment response, underscoring its pivotal role in pathological mechanisms.

The spatiotemporal evolution of network remodeling displays clinical heterogeneity. During the acute phase (<3 months), localized network efficiency reduction predominates around lesion sites, while chronic stages (>6 months) manifest abnormal increases in whole-brain functional modularity. This hyper-segregated network topology may underlie persistent deficits in executive function and emotional integration (30). Such aberrant connectivity patterns likely disrupt emotional processing and cognitive control mechanisms, contributing to impaired daily functioning and social adaptation. Comprehensive investigation of cerebral network reorganization and functional abnormalities holds substantial implications for elucidating post-hemorrhagic pathophysiological processes and developing targeted therapeutic interventions.

Emerging evidence highlights the critical role of iron metabolism dysregulation and oxidative stress in the pathogenesis of PICH-D. During the acute phase of ICH, hemoglobin degradation releases substantial free iron ions, which catalyze reactive oxygen species (ROS) generation via Fenton reactions (Fe²⁺ + H₂O₂ → Fe³⁺+ •OH + OH⁻). This process triggers a cascade of oxidative stress reactions, establishing a neurotoxic microenvironment (31). Concurrent alterations in serum iron-regulatory proteins, particularly elevated ferritin and reduced transferrin levels, demonstrate significant correlations with depressive symptom development (32).

Excessive ROS production induces mitochondrial membrane lipid peroxidation, impairing electron transport chain complexes I-IV function and reducing ATP synthesis efficiency by 40-60%. These metabolic disturbances are exacerbated by mitochondrial DNA damage and cytochrome C release, culminating in neuronal energy crises and apoptotic activation (33). Crucially, systemic iron homeostasis disruption manifests distinct serum biomarkers: hyperferritinemia (>300 ng/mL) indicates iron overload, while decreased transferrin saturation (<20%) reflects impaired iron transport (34). Such systemic dysregulation may permeate the compromised blood-brain barrier, exacerbating iron deposition in limbic structures (e.g., hippocampus and prefrontal cortex). Clinical investigations validate serum ferritin as both a prognostic biomarker and therapeutic target for PICH-D (32).

At the molecular level, oxidative stress impairs neuroplasticity through three primary mechanisms: 1) ROS-mediated suppression of BDNF/TrkB signaling reduces dendritic spine density (35);2) Inhibition of hippocampal neurogenesis (36);and 3) Disruption of glutamate cycling, leading to excitotoxic synaptic accumulation (37). These alterations collectively establish the neurobiological substrate for depressive behaviors. Preclinical studies demonstrate that iron chelation therapy (e.g., desferrioxamine) significantly reduces immobility time in forced swim tests, underscoring its therapeutic potential (38). Emerging therapeutic strategies targeting this axis include precision iron chelation, nano-antioxidant delivery systems, and transferrin receptor modulation. Collectively, interventions addressing iron homeostasis and oxidative damage represent promising avenues for managing PICH-D.

Psychological and social factors significantly contribute to the pathogenesis of post-stroke depression (PSD). The severity of these symptoms demonstrates a positive correlation with the degree of neurological impairment. Post-acute phase patients frequently experience a self-efficacy crisis secondary to sudden functional limitations (hemiparesis, aphasia, etc.), which profoundly impacts daily living autonomy.

Emerging evidence reveals that chronic psychological stress initiates neurobiological cascades through hypothalamic-pituitary-adrenal (HPA) axis hyperactivity. Preclinical investigations demonstrate that sustained stress exposure downregulates hippocampal glucocorticoid receptor expression, impairing negative feedback inhibition and perpetuating cortisol hypersecretion (39). his neuroendocrine dysregulation directly modulates monoaminergic neurotransmission, particularly enhancing serotonin transporter density in the prefrontal cortex which consequently depletes synaptic 5-hydroxytryptamine (5-HT) availability (40).

The stress-buffering hypothesis elucidates how psychosocial factors modulate post-stress depression susceptibility. The stress-vulnerability model posits that adverse life events (e.g., spousal bereavement, financial crises) exacerbate depression risk by compromising psychological resilience thresholds. Epidemiological data from longitudinal cohorts indicate significantly elevated PSD incidence among individuals experiencing major stressors compared to control populations (41).

Notably, there is a two-way relationship between psychosocial stressors and neurobiological mechanisms, creating a self-sustaining “depression-neurodegeneration” cycle. Modern treatment approaches therefore recommend combining psychosocial rehabilitation with biological therapies to break this harmful cycle effectively.

SSRIs, particularly sertraline, remain a first-line pharmacological treatment recommended in current clinical guidelines (e.g., AHA/ASA guidelines) due to their established efficacy and safety profile in stroke populations. A 2019 multicenter randomized controlled trial (RCT) demonstrated that sertraline (50–100 mg/day) significantly reduced Hamilton Depression Rating Scale (HAMD-17) scores after 8 weeks compared to placebo (42). Escitalopram exhibits dual therapeutic benefits through σ1 receptor agonism, with meta-analyses confirming enhanced response rates and concurrent improvement in post-stroke cognitive impairment (43). Clinical protocols mandate thromboelastography monitoring during SSRI administration to mitigate potential coagulation abnormalities, particularly in patients with recent hemorrhage.

Esketamine has emerged as a breakthrough therapy for treatment-resistant cases. Phase III trial results (TRANSFORM-3) revealed that intranasal esketamine combined with oral antidepressants achieved significantly higher remission rates at week 4 compared to placebo plus antidepressants (44). However, its application warrants caution due to transient hemodynamic effects. A recent safety analysis documented associated increases in blood pressure, mandating rigorous cardiovascular monitoring (45).Advanced neuroimaging utilizing resting-state functional magnetic resonance imaging (fMRI) elucidates ketamine’s neuromodulatory effects, particularly enhanced functional connectivity within the default mode network (DMN), which correlates with therapeutic response (46). Notably, current guidelines classify ketamine derivatives as experimental interventions for treatment-resistant depression, restricting their use to specialized settings.

Notably, current guidelines classify ketamine derivatives as experimental interventions for treatment-resistant depression, restricting their use to specialized settings with cardiovascular monitoring due to potential hemodynamic effects.

Minocycline administered at 50 mg twice daily exhibits a dual-pathway therapeutic mechanism for neuroinflammatory modulation, combining microglial activation suppression with synaptic plasticity enhancement (47). Through inhibition of microglial activity, it achieves a significant reduction in pro-inflammatory cytokines IL-6 and TNF-α from baseline level (47), while concurrently upregulating brain-derived neurotrophic factor (BDNF) to higher concentrations compared to placebo (27). This unique immunomodulatory profile, simultaneously addressing neuroinflammatory processes and promoting neurotrophic support, establishes minocycline as a viable adjunctive treatment option for psychiatric disorders associated with neuroimmune dysregulation, particularly those involving both inflammatory pathology and synaptic dysfunction.

The multidisciplinary collaborative approach is implemented through a three-phase intervention model led by neuropsychiatry-focused MDT (Multidisciplinary Team) teams (52). In the acute phase (0-1 month post-onset), neurologists initiate neuroprotective therapies while collaborating with psychiatrists for precise antidepressant titration. During the recovery phase (1-3 months), rehabilitation specialists introduce personalized interventions, such as mirror therapy for post-stroke limb neglect. Transitioning to the maintenance phase (>3 months), psychologists employ mindfulness-based cognitive therapy (MBCT) for relapse prevention. This continuum of care is supported by three operational pillars: weekly standardized MDT case reviews, a cross-departmental intelligent EMR system enabling real-time data sharing, and machine learning models integrating clinical biomarkers for risk prediction. Machine learning models integrating clinical and imaging biomarkers for treatment response prediction, with advanced algorithms such as XGBoost demonstrating superior performance in recent dedicated studies. Specifically, an XGBoost model incorporating clinical indicators (e.g., frontal lobe lesion, NIHSS, PSQI, MMSE) and biochemical markers (e.g., ALB) achieved an AUC of 0.941, accuracy of 87.6%, sensitivity of 82.2%, and specificity of 89.9% in predicting post-stroke depression risk (53). The integrated framework establishes closed-loop management from acute intervention to long-term functional recovery, enhancing therapeutic precision through temporal-stage specialization and multidimensional data synthesis.