Mild Behavioral Impairment is Associated With Incident Cognitive Decline Among Dementia-Free, Racially Diverse Older Adults: Data From the African Americans Fighting Alzheimer's in Midlife (AA-FAIM) Study

OBJECTIVES: To determine whether MBI associates with worse cognitive performance over time and with incident cognitive decline in an older, racially/ethnically diverse cohort at early stages of cognitive change. DESIGN: This observational cohort study followed participants from the Wisconsin Alzheimer's Disease Research Center Clinical Core (WADRC) for up to 13 visits. SETTING: An urban university research center. PARTICIPANTS: Participants from the WADRC Clinical Core were included in this convenience sample if they were without dementia, had undergone at least 1 cognitive assessment, and completed measures of cognitive, clinical and affective function. MEASUREMENTS: MBI was assessed using the Neuropsychiatric Inventory. Linear mixed effects models (LME) were fit to cognitive outcomes Trailmaking Tests A and B (TMT-A, B) and Wechsler Logical Memory (LM). Cox proportional hazard models assessed whether MBI was related to risk for incident global Clinical Dementia Rating Scale (CDR >0). RESULTS: N = 584 participants with mean age 64.6 years, range 46-92.6 years, 59.4% female and 17% African American. LME results indicated participants with MBI exhibited worse age-associated decline on TMT-B, compared to those without MBI (beta=0.008, p = 0.01, CI: 0.002, 0.01, t(337) = 2.4, p = 0.01). MBI at baseline was associated with a significant hazard ratio (HR) indicating an increased risk of decline on the CDR (HR: 2.84; HR 95% CI: 1.68 - 4.81; p = 0.0001). CONCLUSIONS: MBI associated with worse cognitive performance and incident cognitive decline in a racially diverse, older adult sample at early stages of cognitive change. Increased awareness of the late life emergence of neuropsychiatric symptoms is warranted to assist in identification and improve prognostication and treatment of neurodegenerative disease.