Clinical and Neuropsychological Characteristics of ADHD According to Age-of-Onset Criterion in Korean Children and Adolescents.

The aim of this study was to compare the clinical features and neuropsychological profiles of children and adolescents with ADHD according to the age-of-onset defined in the (5th ed.; ). We compared the following three groups: early-onset ADHD group (onset before age 7, = 86), late-onset ADHD group (onset between ages 7 and 12, = 58), and the control group ( = 88). Both early-onset and late-onset ADHD groups had more symptoms and functional impairments than the control group. Also, both ADHD groups scored higher on ADHD Rating Scale, Parent General Behavior Inventory, majority of the subscales of Social Responsiveness Scale, Hyperactivity subscale of Korean Personality Rating Scale for Children, and Omission Errors of Visual Continuous Performance Test compared with the control group. Our results support the extension of age-of-onset criterion made in .