Sex differences not significant for youth bipolar disorder outcomes

Male and female youth with bipolar disorder had similar outcomes, despite substantial literature on sex differences among adults with bipolar disorder, according to study results published in Journal of Clinical Psychiatry.

“To date, there have been no longitudinal studies of sufficient sample size and duration that have stratified the analyses by sex with the specific aim to investigate sex differences in the clinical phenotype of youth [bipolar disorder],” Rachel H.B. Mitchell, MD, MSc, FRCPC, of the department of psychiatry at the University of Toronto Faculty of Medicine in Canada, and colleagues wrote. “Sex differences in [bipolar disorder] may inform sex-specific diagnostic and treatment strategies and guide research on neurobiological mechanisms that may underlie these differences.”

The investigators aimed to pinpoint potential sex differences in psychiatric comorbidity and mood symptomatology among 199 female and 171 male youth with bipolar 1 disorder, bipolar 2 disorder or operationalized bipolar disorder not otherwise specified according to DSM-4 criteria. Participants had been included in the Course and Outcome of Bipolar Youth study and had follow-up data available for 4 years or longer.

Results showed female youth were older than male youth at intake and at age at mood onset. Male youth were more likely to exhibit syndromal ADHD, whereas female youth were more likely to exhibit syndromal anxiety, after adjustment for confounders. The investigators observed trends toward males exhibiting higher rates of substance use disorder and female youth higher rates of non-suicidal self-injurious behavior. However, they reported no sex differences on outcome variables, such as rate of or time to recovery and recurrence.

“Future studies are warranted to better understand the female predominance of [bipolar disorder] in adolescence,” Mitchell and colleagues wrote. “As clinical characteristics do not provide strong signals, findings underscore the importance of incorporating neurobiological data (e.g., sex hormones, neuroimaging phenotypes) to offer insight into plausible underlying mechanisms.”