Background: Apathy, a complex neuropsychiatric syndrome, commonly affects patients with Alzheimer's disease. Prevalence estimates for apathy range widely and are based on cross-sectional data and/or clinic samples. This study examines the relationships between apathy and cognitive and functional declines in non-depressed community-based older adults.

Methods: Data on 1,136 community-dwelling adults aged 50 years and older from the Baltimore Epidemiologic Catchment Area (ECA) study, with 1 and 13 years of follow-up, were used. Apathy was assessed with a subscale of items from the General Health Questionnaire. Logistic regression, t-tests, χ2 and Generalized Estimating Equations were used to accomplish the study's objectives.

Results: The prevalence of apathy at Wave 1 was 23.7%. Compared to those without, individuals with apathy were on average older, more likely to be female, and have lower Mini-mental State Examination (MMSE) scores and impairments in basic and instrumental functioning at baseline. Apathy was significantly associated with cognitive decline (OR = 1.65, 95% CI = 1.06, 2.60) and declines in instrumental (OR = 4.42; 95% CI = 2.65, 7.38) and basic (OR = 2.74; 95%CI = 1.35, 5.57) function at 1-year follow-up, even after adjustment for baseline age, level of education, race, and depression at follow-up. At 13 years of follow-up, apathetic individuals were not at greater risk for cognitive decline but were twice as likely to have functional decline. Incidence of apathy at 1-year follow up and 13-year follow-up was 22.6% and 29.4%, respectively.

Conclusions: These results underline the public health importance of apathy and the need for further population-based studies in this area.