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.
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.
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.
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.

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