ABSTRACT
Attention deficit hyperactivity disorder (ADHD) is among the most frequently diagnosed childhood behavior disorders in the United States. Since its inclusion in the third edition of the American Psychiatric Association Diagnostic and Statistical Manual of Mental Disorders in 1980, there has been a steady increase in the frequency of this diagnosis in children and adolescents (Morris & Morris, 2000; Safer & Krager, 1988). By the early 1990s, it was estimated that between 3% and 5% of the school-age population in the United States had this diagnosis, with boys outnumbering girls by a ratio of 3:1 (Kauffman, 1993). Estimates for 2000 were that 15% of all U.S. children (approximately 7.5 million children) would be diagnosed as having ADHD (Panksepp, 1998).
