Trajectories of Depression and Their Associations with Mortality in Older People in Korea over 12 Years

Background: As the course of depression and depressive symptoms over a lifetime varies between individuals, we used trajectory models based on the Korean Longitudinal Study of Aging to repeatedly measure symptoms over a follow-up period of 12 years to reveal the association with mortality.Methods: Three thousand five hundred sixty-one (1,483 men and 2,078 women) subjects aged over 65 years were included. Using the 10-item Center for Epidemiological Studies Depression Scale (CES-D 10), a trajectory model was classified into different depressive symptom groups by gender. Cox proportional hazards models were used to investigate the association between depression trajectory and all-cause mortality.Results: We identified four trajectories of depressive symptoms in both men and women characterized by low CES-D 10 scores throughout the study: Low trajectory (LT), Moderate high trajectory (MHT), High, but increasing trajectory (HIT), and High, but decreasing trajectory (HDT). The adjusted hazard ratios of the HIT, HDT, and MHT compared with LT in men were 2.12 (95% confidence interval [CI], 1.43-3.16), 1.52 (95% CI, 0.96-2.40), and 1.58 (95% CI, 1.10-2.26), respectively. In women, ratios of each group were 1.62 (95% CI, 1.25-2.10), 0.84 (95% CI, 0.61-1.16), and 1.20 (95% CI, 0.99-1.46).Conclusions: Highly depressive symptoms that increased over the 12 years period were associated with the highest risk of mortality in the Korean elderly population. The trajectory group with remitting depressive symptoms (HDT), despite having a similar baseline level of mood symptoms as the high increasing group (HIT) experienced a lower mortality risk in both men and women.