Comorbidity in attention deficit-hyperactivity disorder.

Attention deficit-hyperactivity disorder (ADHD) has been noted for its high rate of comorbidity. The present study is the first report in Japan evaluating the proportion of comorbidity in ADHD cases presenting in the clinical setting, aiming at clarifying the picture of ADHD in Japan. The subjects consisted of 68 child and adolescent cases meeting criteria for ADHD (Diagnostic and Statistical Manual of Mental Disorders, 4th edn) under treatment at a child psychiatry clinic (IQ > 50, mental age >or= 4 years old).