Inattentive behavior in childhood: epidemiology and implications for development.

Poor concentration is a relatively common childhood problem. The current North American psychiatric diagnostic classification system (Diagnostic and Statistical Manual of Mental Disorders, fourth edition; DSM-IV), American Psychological Association, 1994) differentiates children whose problems are distinguished primarily by symptoms of inattention (ADHD-I) from those whose difficulties are characterized by overactive, impulsive behavior by providing various subtypes within a broad diagnostic category. Yet, comparatively little is known about children who exhibit purely inattentive behavior.