Objective: To investigate gender differences in psychiatric comorbidity patients diagnosed with attention-deficit hyperactivity disorder (ADHD) as adults. Methods: Interviews about current ADHD symptoms and psychiatric comorbidity on axis I and II (Structured Clinical Interview for DSM-IV axis I and axis II) were conducted in a clinical cohort of 168 patients (78 women, 90 men). Independent information on childhood and current symptoms was collected from parents, partners and patient files. Results: The lifetime prevalence of psychiatric comorbidity on axis I reached 92%, and current comorbidity, including autism spectrum disorders and Tourette's syndrome, was 47%. Women had a higher lifetime prevalence of mood and eating disorders compared with men, where substance-use disorders were more frequent. Ten per cent of patients fulfilled diagnostic criteria for a personality disorder. When excluding the general diagnostic criteria, 46% of the patients endorsed the specific criteria for at least one personality disorder. Gender differences were identified with predominance of histrionic personality traits in women and conduct disorder in men. Conclusion: Patients diagnosed with ADHD as adults display an extremely high lifetime axis I comorbidity with a gender-specific pattern similar to the general population. No gender differences were identified with regard to personality disorders; however, an increased prevalence of deviant personality traits was confirmed. This study stresses the importance of evaluating comorbidity among patients diagnosed with ADHD as adults to secure optimal treatment
