Subjective cognitive decline predicts progression to dementia in a multiracial community sample

Abstract

AbstractBackgroundSubjective Cognitive Decline (SCD) is the perception of cognitive decline before such decline is evident on standard neuropsychological testing. SCD is believed to precede the Mild Cognitive Impairment stage of Alzheimer’s disease (AD) when objective cognitive deficits first become evident and has potential as an early marker of AD. However, studies examining SCD have largely focused on non‐Hispanic White populations, limiting its applicability to Blacks and Hispanics, who are known to be at increased risk of developing AD. This study examines the predictive utility of SCD for conversion to dementia in a racially and ethnically diverse sample.MethodParticipants were a total of 5,379 older adults enrolled in a longitudinal, population‐based study of aging. Participants were non‐demented at baseline and were 26% non‐Hispanic White, 31% Black and 44% Hispanic (67% female; age=75±6yrs). SCD was assessed with a questionnaire assessing complaints of memory difficulties. Follow ups of approximately 18‐month intervals assessed for dementia at each visit based on comprehensive assessment of everyday function and cognition. Multi‐group Cox regression models tested main effects of baseline SCD on progression to dementia, and jointly modeled death during follow up as a function of race/ethnicity. Models were adjusted for age, depressive symptoms, sex, years of education, medical comorbidity burden, and enrollment cohort.ResultSCD significantly predicted conversion to dementia in all groups (Non‐Hispanic White HR=1.65 [1.04, 2.61]; Blacks HR=1.62 [1.17, 2.24] and Hispanics (HR=1.74 [1.40, 2.17]). Although multi‐group modeling revealed no significant interactions between SCD and race (p> .05), when depressive symptoms were entered as a covariate in each model SCD significantly predicted conversion to dementia in Blacks (HR=1.77 [1.10, 2.84]) and Hispanics (HR=1.84 [1.36, 2.48]) only.ConclusionSCD predicted conversion to dementia across all racial/ethnic groups. However, when adjusting for depressive symptoms, the predictive utility of SCD remained only among Blacks and Hispanics. This pattern of findings highlights the utility of SCD as a marker of future conversion to dementia in diverse groups, while underscoring the complex association between SCD and depression. Future work should tease apart the basis of the unique pathways between depression and SCD as a function of race/ethnicity.