Background: Apathy is a common neuropsychiatric symptom in Alzheimer's disease (AD) dementia and mild cognitive impairment (MCI). Detecting apathy accurately may facilitate earlier diagnosis of AD. The Apathy Evaluation Scale (AES) is a promising tool for measurement of apathy in prodromal and possibly preclinical AD.
Objective: To compare the three AES sub-scales - subject-reported (AES-S), informant-reported (AES-I), and clinician-reported (AES-C) - over time in individuals at risk for AD due to MCI and advanced age (cognitively normal [CN] elderly).
Methods: Mixed effects longitudinal models were used to assess predictors of score for each AES sub-scale. Cox proportional hazards models were used to assess which AES sub-scales predict progression from MCI to AD dementia.
Results: Fifty-seven MCI and 18 CN subjects (ages 53-86) were followed for 1.4 ± 1.2 years and 0.7 ± 0.7 years, respectively. Across the three mixed effects longitudinal models, the common findings were associations between greater apathy and greater years in study, a baseline diagnosis of MCI (compared to CN), and male gender. CN elderly self-reported greater apathy compared to that reported by informants and clinicians, while individuals with MCI under-reported their apathy compared to informants and clinicians. Of the three sub-scales, the AES-C best predicted transition from MCI to AD dementia.
Conclusion: In a sample of CN elderly and elderly with MCI, apathy increased over time, particularly in men and those with MCI. AES-S scores may be more sensitive than AES-I and AES-C scores in CN elderly, but less reliable if subjects have MCI. Moreover, the AES-C sub-scale predicted progression from MCI to AD dementia.
Keywords: Aged; Alzheimer’s disease; apathy; mild cognitive impairment; symptom assessment.