Patterns of late-life depressive symptoms and subsequent declines in cognitive domains.

Background: Depression frequently co-occurs with cognitive decline, but the nature of this association is unclear. We examined relations of late-life depressive symptom patterns to subsequent domain-specific cognitive changes.

Methods: Depressive symptoms were measured at up to 3 timepoints among 11,675 Nurses' Health Study participants prior to cognitive testing. Depressive symptom patterns were categorized as non-depressed, variable or persistent, based on published severity cutpoints. Outcomes were global, verbal, and executive function-attention composite scores.

Results: Participants with persistent depressive symptoms had worse executive function-attention decline compared with non-depressed participants (multivariable-adjusted mean difference = -0.03 units/year, 95% CI: -0.05, -0.01; p = 0.003); this difference was comparable with 8 years of aging. However, being in the persistent versus non-depressed group was not significantly related to verbal (p = 0.71) or global score (p = 0.09) decline. By contrast, compared with the non-depressed group, those with variable depressive symptoms had worse verbal memory decline (multivariable-adjusted mean difference = -0.01 units/year, 95% CI: -0.02, -0.002; p = 0.03); this group showed no differences for global or executive function-attention decline.

Conclusions: A variable pattern of depressive symptom severity related to subsequent decline in verbal memory, while a persistent pattern related to decline in executive function-attention. Findings could signal differences in underlying neuropathologic processes among persons with differing depression patterns and late-life cognitive decline. Copyright © 2016 John Wiley & Sons, Ltd.