Cognitive decline is a central feature in the aging process. Previous studies have indicated an association between depressive symptoms and cognitive decline in Caucasian populations. However, few studies have examined the effect of changes in depression on the trajectory of cognitive decline. Here, we included 580 participants with normal cognitive ability and complete cognitive and depression data from the Rugao Longevity and Ageing Study (RuLAS). We explored the relationship between depressive symptoms and cognitive decline in these participants. We examined how the change in depressive symptoms affected the trajectory in the HDS-R (the Revised Hasegawa Dementia Scale) scores by comparing cognition function in both the depression deterioration group and the depression steady group by using a linear mixed model. The results indicated that those with deteriorating depression tended to have faster cognitive declines than those with steady depression, indicated by the significance of the interaction term of GDS (Geriatric Depression Scale) groups and time (unadjusted model, β = - 0.673, p < 0.001). The results remained significant after adding demographic covariates. Moreover, we found that those with the worst depressive symptoms at baseline had the worst cognition in subsequent years (GDS = 0 group vs. GDS ≥ group in the unadjusted model: β = - 1.522, p < 0.003), while the slope of change was not significantly different among groups (GDS = 0 group × time vs. GDS > =4 group × time in the unadjusted model: β = - 0.045, p = 0.857). Therefore, we found that depressive symptom deterioration was significantly associated with faster cognitive decline. Medical interventions for depression may decrease the number of older Chinese individuals who experience early-stage cognitive decline.
Keywords: Cognitive decline; Depressive symptoms; Linear mixed model; Older people.