Apathy and risk of probable incident dementia among community-dwelling older adults

Objective To evaluate the association between baseline apathy and probable incident dementia in a population-based sample of community-dwelling older adults.

Methods We studied 2,018 white and black community-dwelling older adults from the Health, Aging, and Body Composition (Health ABC) study. We measured apathy at year 6 (our study baseline) with the modified Apathy Evaluation Scale and divided participants into tertiles based on low, moderate, or severe apathy symptoms. Incident dementia was ascertained over 9 years by dementia medication use, hospital records, or clinically relevant cognitive decline on global cognition. We examined the association between apathy and probable incident dementia using a Cox proportional hazards model adjusting for demographics, cardiovascular risk factors, APOE4 status, and depressed mood. We also evaluated the association between the apathy group and cognitive change (as measured by the modified Mini-Mental State Examination and Digit Symbol Substitution Test over 5 years) using linear mixed effects models.

Results Over 9 years of follow-up, 381 participants developed probable dementia. Severe apathy was associated with an increased risk of dementia compared to low apathy (25% vs 14%) in unadjusted (hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.5–2.5) and adjusted models (HR 1.7, 95% CI 1.3–2.2). Greater apathy was associated with worse cognitive score at baseline, but not rate of change over time.

Conclusion In a diverse cohort of community-dwelling adults, apathy was associated with increased risk of developing probable dementia. This study provides novel evidence for apathy as a prodrome of dementia.