Major Depressive Episodes Are Characterized by a Wide Range of Factors that May Be Predictive of Risk of Recurrence

Analysis of data from a Canadian study indicates that even brief, subsyndromal depressive events are associated with an increased risk of subsequent major depressive episodes, according to research published in the Journal of Affective Disorders.

Although published clinical studies and other research “increasingly recognize the heterogeneity associated with major depressive episodes (MDE),” the implications of episode heterogeneity for long-term prognosis “have not been adequately explored,” according to the authors.

They looked at recurrence risks for MDE after an initial episode, analyzing 15 years of data from a community cohort from a Canadian longitudinal study. Data on MDE duration, severity, and other characteristics were collected during biannual interviews during the study. Episodes were evaluated for characteristics such as “syndromal versus sub-syndromal, duration of symptoms, and indicators of seriousness (activity restriction, high distress or suicidal ideation).”

Using proportional hazards modeling and other analytical approaches, researchers estimated the ability of these variables to predict MDE recurrence. They reported that “Even brief, sub-syndromal episodes not characterized by indicators of seriousness were associated with an increased risk of subsequent MDE. However, episodes meeting diagnostic criteria for MDE, those lasting longer than four weeks and those associated with indicators of seriousness were associated with much higher recurrence risk. Sub-syndromal episodes associated with these characteristics generally predicted subsequent MDE as strongly as the occurrence of MDE itself.”

These findings could have important implications for diagnosis and treatment of patients with major depressive disorder of varying degrees of severity. As even seemingly brief episodes characterized by relatively mild symptoms may “have implications for subsequent MDE risk” and could help clinicians to “identify a range of outcomes that have potential implications for long-term management.”