Additive effect of patient anosognosia and theory of mind deficit on dementia caregiver distress

Introduction Caregiver distress in dementia is multifactorial. The contribution of disease specific factors including anosognosia (poor awareness of cognitive/behavioral deficits) and theory of mind (ToM) deficit (difficulty with understanding other’s perspective) requires further investigation. Method Cross sectional secondary analysis was performed on a dataset of 205 research participants (age = 64.2 ± 9.46): 57 Alzheimer’s disease, 38 behavioral variant frontotemporal dementia, 12 non-fluent primary progressive aphasia (PPA), 24 semantic variant PPA, 18 progressive supranuclear palsy syndrome, 14 corticobasal syndrome, and 42 cognitively normal controls (NC). Anosognosia was measured using the Patient Competency Rating Scale (PCRS-self minus PCRS-caregiver; clinically meaningful anosognosia >20 points difference), ToM deficit was evaluated using The Awareness of Social Inference Test: Social Inference-Enriched (TASIT-SIE), and caregiver distress was measured using the Neuropsychiatric Inventory Questionnaire (NPI-Q) Total Distress score. Differences across syndromes were evaluated controlling for age and sex, and multivariable linear regression was used to determine predictors of caregiver distress. Results Clinically meaningful anosognosia (patient overestimation of function) and ToM deficit were significantly higher in all dementia syndromes compared to NCs. Anosognosia and ToM deficit each independently predicted caregiver distress and had an additive effect ( p < 0.05). Discussion Our findings are consistent with other research showing that anosognosia in individuals with chronic neurological disorders including dementia can increase caregiver distress; however, our results highlight the additive importance of patients’ theory of mind deficits above and beyond their anosognosia. Evaluation of both patient anosognosia and ToM deficit in clinical contexts may provide meaningful information to predict which caregivers are at particular risk for adverse outcomes.