The role of motor excess and instrumented activity measurement in attention deficit hyperactivity disorder.

Motor excess was once recognized as a primary aspect of childhood behavior disorder but has been largely discounted by current investigators despite consistent reference to hyperactivity in titles of articles, chapters, and books. The presumed minor relevance of hyperactivity to attention deficit hyperactivity disorder (ADHD) is based on analogue assessment procedures that remain to be validated. Results of content-valid instrumented behavioral measurements show that ADHD children are pervasively hyperactive. These findings are consistent with recent research showing activity to be an important aspect of temperament and a well-documented factor of externalizing disorders of childhood. Theoretical analyses of the relationship between hyperactivity and ADHD disorder are presented.