Prevalence and correlates of childhood-onset bipolar disorder among adolescents.

AIM: Early-onset bipolar disorder (BD) is associated with a more severe illness as well as a number of clinical factors among adults. Early-onset can be categorized as childhood- (age < 13) or adolescent- (age ≥ 13) onset, with the two displaying different clinical profiles. We set out to examine differences in clinical, and familial characteristics among adolescents with childhood- versus adolescent-onset BD. METHODS: The study included 195 adolescents with BD, ages 14-18 years. Age of onset was determined retrospectively by self-report. Participants completed the semi-structured K-SADS-PL diagnostic interviews along with self-reported dimensional scales. Analyses examined between-group differences for clinical and familial variables. Variables associated with age of onset at p < 0.1 in univariate analyses were evaluated in a logistic regression model. RESULTS: Approximately one-fifth of participants had childhood-onset BD (n = 35; 17.9%). A number of clinical and familial factors were significantly associated with childhood-onset BD. However, there were no significant differences in depressive and manic symptom severity. In multivariate analyses, the variables most strongly associated with childhood-onset were police contact, and family history of suicidal ideation. Smoking and psychiatric hospitalization were associated with adolescent-onset. CONCLUSIONS: In this large clinical sample of adolescents with BD, one-fifth reported childhood-onset BD. Correlates of childhood-onset generally aligned with those observed in the literature. Future research is warranted to better understand the genetic and environmental implications of high familial loading of psychopathology associated with childhood-onset, and to integrate age-related treatment and prevention strategies.