This study is aimed at assessing changes in functioning among young people from the general population with bipolar disorder and major depressive disorder over a period of five years. Specifically, we hypothesized that significant illness progression would take place during euthymia over time in bipolar disorder. We conducted a longitudinal study with 231 people, assessed at baseline and again at a five-year follow-up. A structured clinical interview was used to diagnose participants with mood disorders. A control group without mood disorders was also included. Functioning was assessed with the Functioning Assessment Short Test, and linear mixed models were used to analyze the effect of psychopathology on change in functioning. Mood disorders were associated with significant functional impairment, but functioning significantly improved in both groups over the 5-year follow-up period. Depressive episodes, however, were associated with worse functioning at follow-up, independently of depression severity. In contrast to our initial hypothesis, we found a worsening of functioning in a five-year period associated only with depressive episodes. This suggests that interventions focused on the prevention of mood episodes early in the course of illness may be particularly promising to reduce adverse functioning outcomes.
Copyright © 2021. Published by Elsevier B.V.

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