Validation of apathy evaluation scale and assessment of severity of apathy in Alzheimer's disease

Aim: Apathy is a well-recognized symptom of Alzheimer's disease (AD). The aim of the present study was to validate the Taiwanese version of the Apathy Evaluation Scale, clinician version (AES-C) and assess the severity of apathy in patients with AD. Methods: Comprehensive evaluations were conducted in a total of 144 AD patients. This study used a cross-sectional comparative design. Data were collected from clinical interviews using the AES, the Mini-Mental Status Examination (MMSE), the Neuropsychiatric Inventory (NPI), and the Clinical Dementia Rating Scale (CDR). Results: Internal consistency was indicated by Cronbach's alphas of 0.85; test-retest reliability was 0.89 over a period of 3 days. Criterion-related validity was supported by the fact that AES-C significantly correlated with the apathy scores of the NPI. Factor analysis indicated a three-factor structure. Convergent validity was supported by a positive correlation between the AES-C score and the anxiety score of the NPI. Discriminant validity was supported by the fact that the AES-C scores did not correlate with the depression subscale of the NPI, and the correlation between the AES-C score and the euphoria score of the NPI score was negative. Known-group validity was supported by results showing that AD patients in a moderate stage of dementia (CDR = 2) had significantly higher scores on the AES-C than patients with mild-stage dementia (CDR = 1). Conclusion: The AES-C is a reliable and valid instrument for measuring symptoms of apathy among AD patients in Taiwan.