The Dual Trajectories of Depressive Symptoms and Social Support-A Population-Based Cohort Study Among Swedish Adults Across 23 Years.

Objective: Depression often follows a recurrent or chronic course influenced by various factors. Social support is associated with depression both by quantity and quality, however, the concurrent change with depression is unclear. This study aimed to determine the trajectories of depressive symptoms and social support over 23 years as well as their interrelationship. Methods: We analyzed data from 6787 participants of a Swedish population-based cohort study at four time points and across 23 years. Depressive symptoms were assessed using the Major Depression Inventory and social support was assessed with the Interview Schedule for Social Interaction. The trajectories of depressive symptoms and social support were determined using group-based dual trajectory modeling. Multinomial logistic regression analysis assessed the association between the trajectories of depressive symptoms and social support. Results: Six trajectories of depressive symptoms and three trajectories of social support were identified. The trajectories were highly associated. Individuals without depressive symptoms were likely to have a stable high availability of social support, and those with persistent depressive symptoms were likely to experience a stable low availability of social support. Conclusions: Our findings imply that social support should be considered in the management of depressive symptoms.