Measuring Apathy in Alzheimer's Disease in the Apathy in Dementia Methylphenidate Trial 2 (ADMET 2): A Comparison of Instruments

Abstract

Diagnostic criteria for apathy have been published but have yet to be evaluated in the context of clinical trials. The Apathy in Dementia Methylphenidate Trial 2 (ADMET 2) operationalized the diagnostic criteria for apathy (DCA) into a clinician-rated questionnaire informed by interviews with the patient and caregiver. The goal of the present study was to compare the classification of apathy using the DCA with that using the Neuropsychiatric Inventory-apathy (NPI-apathy) subscale in ADMET 2. Comparisons between NPI-Apathy and Dementia Apathy Interview Rating (DAIR) scale, and DCA and DAIR were also explored. ADMET 2 is a randomized, double-blind, placebo-controlled phase III trial examining the effects of 20 mg/day methylphenidate on symptoms of apathy over 6 months in patients with mild to moderate Alzheimer's disease (AD). Participants scoring at least 4 on the NPI-Apathy were recruited. This analysis focuses on cross-sectional correlations between baseline apathy scale scores using cross-tabulation. Of 180 participants, the median age was 76.5 years and they were predominantly white (92.8%) and male (66.1%). The mean (±standard deviation) scores were 7.7 ± 2.4 on the NPI-apathy, and 1.9 ± 0.5 on the DAIR. Of those with NPI-defined apathy, 169 (93.9%, 95% confidence interval [CI] 89.3%-96.9%) met DCA diagnostic criteria. The DCA and DAIR overlapped on apathy diagnosis for 169 participants (93.9%, 95% CI 89.3%-96.9%). The measurements used for the assessment of apathy in patients with AD had a high degree of overlap with the DCA. The NPI-apathy cut-off used to determine apathy in ADMET 2 selects those likely to meet DCA criteria.