Gender differences in ADHD adults during clinical trials with atomoxetine

Introduction: Patients with ADHD exhibit several consistent gender differences, a male preponderance and more males with externalizing disorders (conduct and oppositional defiant disorder). Objective: To examine gender differences in a very large clinical trial of adults with ADHD. Methods: Data from two identical placebo-controlled studies of atomoxetine in adult ADHD using 535 subjects at 31 sites were combined1. The studies lasted 8 weeks and both showed positive medication-placebo differences. Most current Axis-I diagnoses were exclusionary criteria. Results: The male/female ratio of this self-referred population was 2.4:1, lower than in child studies2. In contrast to a predominance of an inattentive ADHD diagnosis subtype in female children, these adult females were more frequently combined type versus the males. Females were rated as more impaired on every measure of ADHD symptoms including total CAARS-INV, total WRAADDS3, and subscales of both measures. Females were rated as having more emotional symptoms on the WRAADDS emotional dimension, lifetime SCID-P psychiatric diagnoses, HAM-A, and HAM-D. Females exhibited significantly greater improvement on the WRAADDS emotional dimension but not on similar items in the Psychological Well-Being Scale. There were no significant gender by treatment effects in the CAARS-INV or CGI-S scores. Conclusion: These females with ADHD displayed significantly greater ADHD symptoms and emotional impairment on multiple measures. On the WRAADDS emotional dimension they responded better to treatment, than their male counterparts. Past research shows that ADHD is much more common in males particularly in pediatric samples. Children exhibit few gender differences on a consistent basis except in the area of associated symptoms. The present study addresses whether ADHD adults displayed gender differences at screening or in treatment response using data from the largest studies ever conducted in ADHD adults.