Sex and Gender Differences in Long-Term Outcomes of ADHD

Background. Attention-Deficit/Hyperactivity Disorder (ADHD) is a prevalent childhood-onset disorder, with increased risk for negative long-term outcomes in adulthood. These outcomes may differ between men/boys and women/girls. Although these differences may stem from biological sex-related and sociocultural gender-related factors, most studies do not distinguish between them. The current study investigated influences of sex-assignment and gender-expression of childhood ADHD on outcomes. Methods. This study includes an 18-year follow-up of 283 children with and without ADHD. To asses if sex and gender-expression expression (sum score of the Traditional Masculinity-Femineity scale) moderated a variety of long-term outcomes in those with and without ADHD, women (n=50, Mage=27.36) and men with ADHD (n=104, Mage=29.40), and women (n=77, Mage=28.32) and men without ADHD (n=55, Mage=27.94) were analyzed, and the unique role of gender-expression was explored in a final model including both sex and gender-expression. Results. Sex and gender-expression were highly similar (r=.94). Both sex and gender-expression interacted with group for social functioning, but not on the other domains. Men with ADHD, as well as those with higher levels of masculinity, were more likely to show lower social functioning compared to women with ADHD and controls. There were no unique moderating effects. Conclusions. On most long-term outcomes of childhood ADHD, sex or gender did not play an important role. Gender-expression did not pose unique risks in our predominantly cis-gendered sample, suggesting other aspects of gender may be more relevant in such a sample.