Aging
Association of depressive symptoms with cognitive decline in the presence of truncation by death among adults age 90+ Alexander Ivan B. Posis* Alexander Ivan B. Posis Hilary L. Colbeth L. Paloma Rojas-Saunero Ruijia Chen Rifat B. Alam Kristen M. George Paola Gilsanz María M. Corrada Rachel A. Whitmer
Background: Depressive symptoms are associated with faster cognitive decline and earlier mortality. This association is unclear among those aged 90+. We tested associations of depression with cognitive decline, while accounting for death as a truncation event, among the oldest-old.
Methods: Baseline depressive symptoms were assessed in the LifeAfter90 Study (2018-2022) using the 15-item Geriatric Depression Scale (GDS) where greater scores suggest greater depressive symptoms. Executive function (EF), semantic memory (SM), and verbal episodic memory (VM) were measured every 6 months using the Spanish and English Neuropsychological Scales and z-scored to baseline. Time to all-cause mortality was calculated from time from enrollment to death. We fit linear mixed-effects (LME) models for cognitive outcomes. To account for death as a truncation event, we also fit joint models (JM) using LME and Cox proportional hazards submodels. All models adjusted for age, gender, race, ethnicity, and education.
Results: At baseline, the average age of the 944 participants was 92.4 (SD=2.4) with average baseline GDS score of 2.9 (SD=2.6). Mean follow-up time was 1.8 (SD=1.3) years and 26% died over follow-up. Overall, 23.5% of the sample identified as African American/Black, 23.9% as Asian, 17.5% as LatinX, 8.5% as Multiracial/Other, and 26.6% as White. Greater GDS was associated with a greater hazard of mortality (HR=1.10, 95% CI 1.05-1.14). Longitudinal results were similar for LME and JM. Every 1-point increase in GDS was associated with faster decline in EF (βLME=-0.02, 95% CI -0.02,-0.01; βJM=-0.01, 95% CI -0.02,-0.001), SM (βLME=-0.01, 95% CI -0.02,0.001; βJM=-0.01, 95% CI -0.02,-0.001), and VM (βLME=-0.01, 95% CI -0.02,0.001; βJM=-0.01, 95% CI -0.02,-0.003).
Conclusion: Greater depressive symptoms were associated with faster time to mortality and cognitive decline. Findings highlight the negative cognitive health consequences of depressive symptoms.