Terminal Increases in Depressive Symptoms in a Multinational Twin Consortium

In later older adulthood, individuals report increased depressive symptoms, whereas gender differences in depressive symptoms narrow. We evaluated whether terminal decline (i.e., accelerated worsening in proximity to death) explained these patterns. We examined the longitudinal trajectories of depressive symptoms in 2,411 participants (baseline age: 29-95 years) from the Interplay of Genes and Environments Across Multiple Studies consortium representing three countries (Sweden, Denmark, and Australia). Joint modeling revealed that individuals reporting larger annual increases in depressive symptoms after age 70 were at increased risk of death. Piecewise linear multilevel models with random changepoints revealed accelerated increases in depressive symptoms approximately 4 years before death. Co-twin control analyses with 98 twin pairs found that the deceased twin had significantly larger accelerations in depressive symptoms compared with the surviving twin. Men experienced more severe mortality-related increases compared with women. Terminal decline partially explains the increase in depressive symptoms in later older adulthood.