Theory of Mind Deficits and Awareness in Alzheimer's Disease

Social cognition (SC) is often impaired by dementia, contributing to difficulties with relationships and social isolation. Additionally, people with dementia frequently have impaired awareness of their impairments, which may worsen distress for them, their family, and friends. We investigated SC in people with Alzheimer's disease (PwAD), awareness of SC, and whether PwAD overestimate SC abilities compared to healthy controls (HC).

Participants completed the Interpersonal Reactivity Index perspective-taking subscale (IRI-PT), a self-report measure of SC, and The Awareness of Social Inference Test (short form) (TASIT-S), a task-based measure of SC. Insight was evaluated by comparing self-assessment with TASIT-S performance. The Addenbrooke's Cognitive Examination (version 3; ACE-III) measured general cognition.

We recruited 70 PwAD (mean age = 78.13; mean ACE-III = 71.80) and 17 HC (mean age = 71.53; mean ACE-III = 96.65). PwAD self-reported lower theory of mind (ToM) (IRI-PT = -2.16, 95% CI = -0.33 to 4.64, p = 0.09) and performed worse on TASIT-S emotion recognition (-2.04, 95% CI = -2.89 to -1.20, p < 0.001), sarcasm recognition (-0.91, 95% CI = -1.66 to -0.16, p = 0.02), and ToM assessments (-1.42, 95% CI = -2.27 to -0.57, p = 0.001). There was no significant relationship between IRI-PT and TASIT-S ToM in either group, nor in the participant group as a whole. We categorised "under-estimators" (low IRI-PT, high TASIT-S ToM), "over-estimators" (high IRI-PT, low TASIT-S ToM), and "congruent-estimators" and found that lower ACE-III was associated with ToM over-estimation.

Differences in self-reported and task-assessed SC were observed between PwAD and HC, but self-estimated and task-assessed ToM were not associated, suggesting that SC self-estimation is unreliable in PwAD and possibly in healthy older adults.