Apathy, cognition and beta amyloid in African Americans in the AA‐FAIM cohort

Abstract

AbstractBackgroundThe prodrome of cognitive declines and/or dementia may include late‐life neuropsychiatric symptoms such as apathy. In primarily non‐Hispanic White samples, apathy associates with both cognition and amyloid deposition in cognitively intact patients and those with Alzheimer’s disease (AD). However, little is known about these relationships in African Americans, who are both disproportionately affected by AD and under‐represented in AD research. Apathy could reflect higher levels of proteinopathy or occur co‐morbidly, exacerbating its deleterious effects. We examined associations between apathy and cognition and their potential moderation by plasma beta amyloid in cognitively healthy African American participants.MethodStudy participants enrolled in African Americans Fighting Alzheimer’s In Mid‐Life(AA‐FAIM, a linked study to the WRAP and Wisconsin ADRC) were included in the analytic sample (N = 166; Table 1) if they had ≥1 cognitive visits, plasma amyloid biomarker data, and apathy ratings by study partners using the Neuropsychiatric Inventory Questionnaire (NPI‐Q) or the Apathy Evaluation Scale (AES). Cognitive outcomes included performance on measures of processing speed, mental flexibility and immediate and delayed memory. We used linear mixed models to examine association of baseline apathy with cognitive performance measures at multiple time points, and the moderation of apathy‐cognition relationships by plasma Aβ42/40 ratio (C2N, USA). Apathy‐cognitive outcome pairings were selected based on significant findings from a proof‐of‐concept linear mixed effects analysis of the full Wisconsin ADRC sample.ResultResults are shown in Table 2. Among AA‐FAIM participants, NPI‐Q apathy was associated with RAVLT immediate (estimate = ‐7.7, p = .001) and delayed recall (estimate = ‐3.2, p = .001). However, AES was unrelated to Trails A or B performance. There were no associations between plasma amyloid or the Aβ42/40*apathy interaction term with any cognitive outcomes.ConclusionPartner‐rated apathy, but not plasma Aβ42/40, was related to cognition in our African American participants, an important finding given limited data available on this population. It will be critical to address apathy and its antecedents to improve the cognitive and affective health of African American older adults. Future research needs to expand cohorts to African American and other diverse populations to investigate disease mechanisms in Alzheimer’s disease and related dementias more inclusively.