Anosognosia is a historical term introduced by Babinski (1) to describe the clinical phenomenon in which patients appeared to lack “subjective” or conscious awareness of their paralyzed limb following a cerebrovascular accident (CVA). The term implied a complete loss or disruption of self-awareness of an impaired neurological function, which is often resolved within hours to days following the abrupt onset of a brain lesion. Progressively, it became obvious to clinicians that patients with various brain disorders tended to underreport their symptoms, including cognitive decline in dementia (2), socially inappropriate behaviors in post-acute patients with a history of severe traumatic brain injury (3), and movement disturbances in such conditions as Parkinson’s disease (4) and Huntington’s disease (5). It was also noted that an underreporting or apparent lack of awareness could exist for changes in personality associated with neurodegenerative diseases (6) and schizophrenia (7).

In these later conditions, the degree of “underreporting” varies in individuals, suggesting that there is a “gradient of subjective unawareness” that could not be captured in the historical term “anosognosia.” Consequently, the term “impaired self-awareness” (ISA) eventually emerged and has been used to describe “partial, but not complete unawareness” of cognitive, affective, or motor disturbances/impairments (8, 9).

Attempts to identify neuropsychological correlates of ISA have typically focused only on cognitive measures. More specifically, impaired performance on measures of executive functions and/or performance on various memory tests has been observed in patients with mild cognitive impairment (MCI) or early probable Alzheimer’s dementia (AD) (10–12). While this approach reflects the predominant cognitive profile of AD, it may provide incomplete insight into the underlying mechanisms. Additionally, this narrow focus overlooks the broader clinical implications: impaired self-awareness can compromise treatment adherence, hinder rehabilitation, and increase caregiver burden. Previous studies have also shown that patients with MCI and early probable AD may present with motor abnormalities (13–15) as well as various neuropsychiatric symptoms, which include apathy, indifference, or appearing “emotionally flat” (16–18). These non-cognitive features may also contribute to ISA. Investigating ISA across cognitive, motor, and affective domains offers a more comprehensive perspective and may reveal novel mechanisms that influence functional outcomes and quality of life throughout the Alzheimer’s disease continuum.

More recent studies have reported finger tapping abnormalities in MCI and early AD (15, 19–21). Finger tapping variability has been shown to be larger in the non-dominant hand in persons with MCI and AD compared to normal functioning individuals (19) and those with subjective memory complaints (SMC) (20). Furthermore, the number of “invalid” tapping responses (i.e., finger tapping movements that did not advance the number on a mechanical counter) was significantly greater in MCI and early probable AD patients versus those with SMC and normal controls (20).

Recent studies have shown that MCI patients tend to overestimate their performance across cognitive domains (22), especially regarding visuospatial memory (23). However, individuals with SMC tend to overreport (not underreport) their memory difficulties (24, 25). This pattern may reflect reduced awareness of their abilities versus any disabilities or impairments observed on clinical examination. Empirical studies examining the neuropsychological correlates of ISA in persons with MCI and AD have typically excluded individuals with SMC. Including this group in studies of ISA may clarify what factors influence disparities in the perception of functional abilities by the patient and an informant.

Clinically, ISA can be measured using the Patient Competency Rating Scale (PCRS) and PCRS-Relative Form (PCRS-R) (26). The PCRS is a brief questionnaire consisting of a series of statements that assess a patient’s perceived functional competency across various domains, such as activities of daily living, interpersonal and social functioning, cognitive abilities, and emotional and behavioral regulation. The parallel form, the PCRS-R, is completed by a relative or “significant other” (friend, partner, etc.) who knows the patient well. All responses are rated on a Likert scale, ranging from one (Not at all capable) to five (Very capable). By analyzing the discrepancy between patient and informant ratings, these two measures have been used in several studies to measure ISA, including in traumatic brain injury (27, 28); MCI and early probable AD (29); Parkinson’s disease (30); multiple sclerosis (31, 32); brain tumors and other cancers (33); and stroke (34). In patients with known brain disorders, ISA broadly refers to a disturbance in self-awareness that can affect multiple domains, including cognitive, emotional, and functional abilities. For the purposes of the present study, we operationalize ISA as the degree to which patients either overestimate or underestimate their functional autonomy compared to informant reports of everyday competence.

While the reliability and validity of relatives’ reports has been questioned, several studies have shown that their ratings are typically positively associated with the patient’s actual neuropsychological test performance (35–38). This has been found in both normally functioning individuals (39) and those with cognitive impairments (40, 41).

As part of an ongoing study in persons with SMC, MCI, and early probable AD (20), patients and their accompanying relative were asked to complete the PCRS and PCRS-R, respectively. Based on the existing literature, we predicted that people with MCI and probable early AD would tend to report higher levels of functional abilities on the PCRS compared to relatives’ reports on the PCRS-R. Moreover, we predicted this tendency to describe oneself as being more functionally competent than what relatives report would be significantly associated with worse test performance on measures of executive functioning and memory, as well as on measures of affect expression and perception. We further hypothesized, given recent research findings (20), that the number of invalid tapping responses (particularly in the non-dominant hand) using the modified version of the Halstead Finger Tapping Test (42) would significantly correlate with the degree of reduced awareness (i.e., overreporting or overestimating one’s functional abilities). Finally, it was predicted that people with SMC would tend to report lower levels of functional abilities on the PCRS compared to relatives’ reports of their functional abilities on the PCRS-R.

The findings of the present study support the hypothesis that patients with SMC tend to underreport their functional abilities and patients with MCI and early probable AD tend to overreport their functional abilities. This finding is compatible with other reports in the literature (25). The present study also provides supportive evidence for the hypothesis that older individuals with known or suspected memory impairments who overstate their functional abilities have lower test scores on neuropsychological measures sampling both cognitive and non-cognitive domains of functioning. This study is somewhat unique in that it included research participants that were expected to both overreport and underreport their functional abilities in comparison to relatives’ perceptions. This methodological approach was used to capture a larger range of disparate perceptions, thus providing a more detailed examination of the strength and direction of their neuropsychological correlates.

ISA has been associated with global cognitive impairment in patients with dementia (50). It is thus not surprising that overall measures of global cognitive functioning (such as the BNI Total Score and the WAIS-IV Full Scale IQ) had mild to moderate negative correlations with patients’ tendencies to overstate their functional abilities (ρ = −0.48 and ρ = −0.36, respectively). What is somewhat surprising and not an anticipated finding was that the BNI Speech and Language subtest score showed the highest correlation with overestimated functional abilities compared to relatives’ reports (ρ = −0.65). None of the research participants exhibited significant aphasia, as this would have precluded completion of the PCRS. The BNI Speech and Language subtest includes screening measures of auditory comprehension, naming, and the ability to add and subtract numbers. These latter abilities are known to decline in the early stages of a dementing condition (50). Patients with early AD showed the greatest tendency to overrate their functional competency (see Figure 1), which may be partly attributable to their difficulties comprehending the questions.

Not surprisingly, the level of memory impairment moderately correlated with the discrepancy scores of functional competencies (e.g., BVMT-R T-score, ρ = −0.54), as predicted. It is important, however, to note that the degree of the person’s memory impairment often does not correlate with the strength of their impaired awareness of their memory impairment (51).

Other factors than cognitive deficit per se may play a role in the apparent lack of awareness of functional limitations in everyday life. In this study, we explored whether motor and affective functions played additional roles. The number of invalid taps in the non-dominant hand positively correlated with discrepancy scores. The degree of correlation was moderate (ρ = 0.44). Invalid tapping responses may be a motor manifestation of a failure at executive control of sustained controlled movements when the individual is fatigued by the task [see (20)]. It may also reflect a breakdown in what Luria (52) referred to as the “kinetic melodies” of the brain. Regions underlying this ability were hypothesized to include frontal and parietal networks (52). In modern day terminology, these networks overlap with the Default Mode Network, which has been associated with frank anosognosia in persons with dementia (53), and within the posteromedial parietal cortex (PMC), which is affected by amyloid deposition in Alzheimer’s disease’s early stages (54). Ilardi et al. (55) hypothesized that evaluating PMC-related domains, such as episodic memory, hand-eye coordination, ISA, and working memory, could facilitate early diagnosis and have significant prognostic value for conversion from MCI to early AD.

In the present study, performance on the TMT Part B did not significantly correlate with discrepancy scores (ρ = −0.30, p = 0.08), indicating no strong association with either over- or underestimation. Additionally, the WAIS-IV composite score of working memory did not correlate with ISA (ρ = −0.29, p = 0.09). Other investigators have reported similar findings in individuals with MCI or mild dementia (12). While these findings do not support the hypothesis that impaired executive functioning is positively correlated with reduced self-awareness, it is possible that these measures of executive dysfunction are not sufficiently sensitive to predict such a relationship. For example, the number of preservative errors on the Wisconsin Card Sorting Test has been shown to be positively related to ISA in persons with severe TBI (56), while the number of categories achieved have not been (3). Determining exactly which measures of executive dysfunction may contribute to impaired self-awareness in MCI and early AD requires further investigation.

While the present study revealed a positive correlation between performance on the BNI Affect subtest with the relatives’ ratings of functional competencies in everyday life (ρ = 0.51, p = 0.003), the relationship of this measure of affect expression and perception to level of discrepancy scores revealed only a mild negative correlation (ρ = −0.36, p = 0.047). However, these associations were not statistically significant after more rigorous analysis. Connecting changes in affect expression and perception with impaired or reduced awareness of abilities versus disabilities is a complicated task. In people with SMC, they perceive themselves as less functionally competent than their relatives. This perception may relate to associated difficulties with anxiety and depression commonly reported in this heterogeneous group (57).

Depressive symptoms are known to negatively affect self-perception, and several studies have documented an inverse relationship between ISA and depression (17, 58, 59). In patients with SMC, preserved language abilities may allow for accurate comprehension of self-report items, but higher levels of depression might lead to a more pessimistic self-assessment and underreporting of abilities. Conversely, in patients with MCI and early probable AD dementia, subtle language deficits may interfere with accurate self-evaluation, potentially resulting in an overestimation of abilities despite lower depressive symptoms. Together, these findings suggest that depression could modulate self-report accuracy differently across clinical subgroups, warranting further investigation into the interplay between mood, language, and self-awareness in older adults.

It is important to note that the current study does not distinguish between ISA and denial in this patient population, a differentiation emphasized by Prigatano et al. (60). Both phenomena can contribute to discrepancies between self-reported and relative-reported functional abilities, yet their underlying mechanisms appear distinct. ISA is thought to represent a neuropsychological impairment, while denial appears to reflect a psychological method of reducing anxiety associated with cognitive decline (61). Future studies should incorporate structured clinical interviews and behavioral assessments that specifically probe for features of denial, such as avoidance of discussing distressing information or discouraging the examiner from asking further questions about the patient’s clinical state.

The major limitations of this study are the sample size and the potential bias of a convenience sample. Patients were originally recruited for this study because they were referred for a clinical neuropsychological evaluation. Several patients with SMC were not accompanied by a relative or significant other, and therefore, a PCRS-R was not obtained. The sample size was, therefore, relatively small. In contrast, many patients with early AD had trouble understanding the questions on the PCRS and could not complete it. Typically, only their relatives completed the PCRS-R. This resulted in a small number of AD patients having both a PCRS and PCRS-R data set.

We did not conduct a formal a priori power analysis, and sample size was limited to available participants. Accordingly, regression results should be interpreted cautiously and confirmed in future studies with larger samples. It is recognized that these convenience samples may not be representative of larger groups of patients with SMC, MCI, or early probable AD. However, these patients’ neuropsychological test findings provide supportive evidence that they demonstrate the type and level of cognitive impairments reported in the literature when large samples are studied (62, 63).

The absence of a formal measure of caregiver stress in our dataset may have influenced the informant ratings on the PCRS-R, potentially contributing to the observed group differences. Future research should address this by incorporating caregiver burden assessments to better understand its potential impact on informant-based evaluations.

In conclusion, we found that reduced self-awareness of functional abilities, measured by the discrepancy between patients’ and their relatives’ ratings, correlates with impairments in language, memory, affect perception and expression, finger tapping movements, and overall cognitive status. Notably, a tendency to overestimate functional abilities was linked to greater cognitive, affective, and motor deficits. These findings underscore that underlying language capabilities may influence how patients understand the questions being asked, potentially skewing findings on reduced awareness. Additionally, the present study highlights the importance of incorporating both cognitive and non-cognitive measures (i.e., affect and motor) when assessing factors associated with reduced or impaired self-awareness. Finally, the strong associations between relative reports of functional abilities and objective neuropsychological performance provides empirical support of the value of relatives’ independent ratings of functional competencies in older individuals with known or suspected memory impairments.