Female patients tend to be more often diagnosed with ADHD inattentive subtype. Many of these females deny an earlier childhood history of hyperactivity or disruptive behaviours and hence may have been clinically overlooked in childhood, while their male counterparts may have presented with ADHD combined subtype which tends to be more easily identified and diagnosed.

Participants will learn about gender differences in ADHD diagnosis and epidemiology.

To examine gender differences in the age of first diagnosis of ADHD in a clinical population.

The study sample consisted of 118 males and 61 females (ages 17–69). Each patient was evaluated and diagnosed by an experienced psychiatrist. Clinical measures (administered by a trained psychometrist) included the CAARS (self and observer versions), BRIEF (self and informant versions), CAADID (history and structured interview), ASRS, CPT, Beck Anxiety and Beck Depression Inventories. Patients were referred by family physicians to a large out-patient metropolitan psychiatry program specializing in ADHD. Information regarding childhood diagnosis was collected retrospectively during the clinical interview.

In this study the mean age of diagnosis (ADHD) for males was 31.2 years versus 32.1 for females. Neither t-test (p = 0.44) nor non-parametric testing using Mann-Whitney U Test (p = 0.67) showed any statistical differences between the two groups.

In the present study there were no difference in the mean age of first diagnosis between male and female subjects. In the present study Further studies are needed to clarify this question. Selection factor may have been a factor in these results.