Comparing Symptoms of Major Depression in Youth with Confirmed Versus Suspected Bipolar Disorder.

Background: While numerous studies have compared symptoms of major depressive episodes (MDEs) associated with bipolar disorder (BD; i.e., bipolar depression) versus major depressive disorder (MDD; i.e., unipolar depression), little is known about this topic in youth. We compared MDE symptoms in youth with BD with youth with suspected BD who have similar clinical and familial characteristics aside from having BD. Methods: MDE symptoms based on Kiddie Schedule for Affective Disorders and Schizophrenia for School Age Children (K-SADS) Depression Rating Scale items for the most severe past episode were compared in youth, ages 13-21 years, with BD ( n  = 208) versus suspected BD ( n  = 165). Diagnoses were confirmed via semistructured interviews. Symptoms with between-group differences ( p  < 0.05) in univariate analyses were evaluated in a multivariate forward stepwise regression. All analyses controlled for age and sex. Results: Youth with BD had significantly higher (more severe) ratings on depressed mood ( p  = 0.001, η 2  = 0.05), irritability ( p  = 0.037, η 2  = 0.02), anhedonia ( p  = 0.004, η 2  = 0.04), negative self-image ( p  < 0.001, η 2  = 0.07), hopelessness ( p  = 0.04, η 2  = 0.02), fatigue ( p  = 0.001, η 2  = 0.05), hypersomnia ( p  = 0.001, η 2  = 0.05), suicidal ideation ( p  = 0.04, η 2  = 0.02), and recurrent thoughts of death ( p  < 0.001, η 2  = 0.05). In regression analyses, the only symptom that remained significant in the BD group was depressed mood ( p  = 0.002). Conclusions: These findings demonstrate greater severity of depressive symptoms in youth with BD versus MDD across mood, and cognitive and neurovegetative symptom domains. These differences are especially noteworthy given that the MDD group was highly similar to the BD group, aside from BD diagnosis. Present findings emphasize the need for novel treatment approaches to bipolar depression in youth, and for studies examining potential mechanisms underlying the increased severity of bipolar depression.