Abstract
BACKGROUND: Attention-deficit/hyperactivity disorder (ADHD) is a neurodevelopmental disorder that often persists into adulthood, significantly impacting daily functioning and quality of life. Sex differences influence ADHD presentation, with females experiencing delayed diagnosis and distinct patterns of severity and comorbidities. Exploring these differences is essential for improving diagnostic accuracy and developing tailored interventions. This study examines ADHD severity, psychiatric comorbidities, and functional impairment by ADHD subtype and sex. METHODS: This population-based study included 900 adults diagnosed with ADHD. ADHD severity, comorbidities, and functional outcomes were assessed using validated tools. Bivariate analyses and General Linear Models (GLMs) were applied to examine sex- and subtype-specific effects and their interactions. RESULTS: Females exhibited greater ADHD severity (p < 0.001), higher levels of depression (p = 0.003) and anxiety (p < 0.001), lower substance use (p < 0.001), poorer functioning (p = 0.039), and greater disability (p = 0.001) than males. No significant sex differences were found in ADHD subtype distribution or age of symptom onset; however, females were diagnosed with ADHD later than males (p < 0.001). The combined ADHD subtype was associated with greater clinical severity, higher levels of depression, anxiety, and impulsive symptoms, increased substance use, and greater disability. A significant interaction between sex and subtype was observed only for disability, with females in the combined subtype exhibiting the most pronounced impairment. CONCLUSIONS: ADHD presents differently across sexes and subtypes, with specific interactions influencing disability. These findings emphasize the importance of considering sex and ADHD subtype independently to enhance diagnostic accuracy and develop targeted treatment strategies.