Association of Depression Dimensions With Cognitive Functioning in Community-Dwelling Oldest-Old Adults: The LifeAfter90 Study.

OBJECTIVES

The oldest-old adults (90+) constitute the fastest-growing demographic at the highest dementia risk among older adults. Depression, a common risk factor, inherently presents with heterogeneous clinical manifestations. Here, we explored the associations of the predominant depression dimensions with cognition in the LifeAfter90 study.

METHODS

The LifeAfter90 study consists of racially/ethnically diverse community-dwelling adults of >90. Cognitive assessments measured episodic memory, semantic memory, and executive function. Baseline depression was measured by the Geriatric Depression Scale-15 item (GDS-15), yielding dimensions of Dysphoria, Withdrawal-Apathy-Vigor, Anxiety, Hopelessness, and Subjective Memory Complaint (SMC). We used generalized linear mixed models to explore associations between depression dimensions, and cognitive outcomes at baseline and over time adjusting for demographic factors.

RESULTS

The cohort (n = 960, mean age 92.4 ± 2.3 years, 61.56% female) was very racially and ethnically diverse with 27% of participants identifying as White, 24% as Asian, 23% as Black, and 19% as Latino. Common complaints included not identifying as "full of energy" (52.45%), preference to "stay home" (46.31%), and "dropped activity" (40.0%), and 25% reported SMC. Depression dimensions showed distinct associations with cognitive outcomes: SMC correlated with worse global cognition, executive function, and verbal episodic memory (all ps < .0001). Hopelessness was associated with worse executive function (p < .001). Over 1.2 years, baseline hopelessness showed a trend for a faster decline in episodic memory (β = -0.22; p = .035).

DISCUSSION

In the oldest old, specific dimensions like SMC and hopelessness may help identify individuals at high risk for cognitive decline in this highly vulnerable population.