Patterns, predictors, and outcome of the trajectories of depressive symptoms from adolescence to adulthood.

Background The long-term trajectory of depressive symptoms has a heterogeneous pattern. Identifying factors associated with different trajectories and outcomes may have important theoretical and clinical implications. This study explored patterns of depressive symptom trajectory from adolescence to adulthood, and their relationship with subsequent psychiatric disorders. Method A sample of 816 participants (58.8% girls; M = 16.58 years old at baseline, SD = 1.21) from a large community sample were interviewed four times during adolescence and adulthood. Depressive symptoms were also assessed. Symptom trajectory identification was based on latent class mixed modeling. Logistic regression was used for predicting emotional and drug use disorder over age 30. Results Three trajectories of depressive symptoms were identified: "decreasing symptom" (decreasing trajectory of symptoms; 15.1% of participants), "increasing symptom" (initially decreasing pattern of symptoms and then increasing; 6.1% of participants), and "normative symptom" (consistently low symptom levels; 78.8% of participants). Predictors of the increasing symptom trajectory were high level of loneliness and state anxiety, presence of an emotional disorder, and low involvement in physical exercise at baseline. This trajectory membership predicted the development of anxiety disorders over age 30. Predictors of the decreasing symptom class were being female and high level of worry at baseline. Conclusions Long-term trajectories of depressive symptoms are heterogeneous, with each trajectory having different predictors and are associated with different outcomes during adulthood.