Sex Differences in the Longitudinal Course and Outcome of Bipolar Disorder in Youth.

Objective: Despite substantial literature on sex differences in adults with bipolar disorder (BD), little is known about this topic in youth; this study examines sex differences in mood symptomatology and psychiatric comorbidity in prospectively followed youth with BD.

Methods: A subsample of the Course and Outcome of Bipolar Youth study (N = 370; female n = 199, male n = 171) enrolled October 2000-July 2006 (age at intake = 7-17.11 years) who met DSM-IV criteria for bipolar I disorder (BD-I; n = 221), bipolar II disorder (BD-II; n = 26), or operationalized BD not otherwise specified (BD-NOS; n = 123) with ≥ 4 years follow-up was included. Analyses examined sex differences at intake and, prospectively, in mood symptomatology and psychiatric comorbidity for a mean ± SD follow-up of 10.5 ± 1.72 years.

Results: Females were older than males at intake (mean ± SD age = 13.33 ± 3.32 vs 12.04 ± 3.16 years; P = .0002) and at age at mood onset (9.33 ± 4.22 vs 7.53 ± 3.74 years; P < .0001). After adjustment for confounders, males spent more time with syndromal ADHD (Padjusted = .001) and females spent more time with syndromal anxiety (Padjusted = .02). There were trends toward males spending more time with substance use disorder and females having more non-suicidal self-injurious behavior (Padjusted = .07 and .09, respectively). There were no sex differences on outcome variables, including rate of or time to recovery and recurrence.

Conclusions: Contrasting with adult literature, this study identified minimal sex differences in the course of youth with BD. Longer-term studies are needed to clarify if youth-onset BD remains a "sex neutral" subtype of BD or diverges according to sex in adulthood.