Three different measures were used to assess ADHD severity and impairment. First, the Kiddie Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version (K-SADS-PL; Kaufman, Birmaher, Brent, Rao, & Ryan, 1996), a semi-structured parent interview was used to assess ADHD severity in children. Evaluators were either Ph.D. level psychologists or doctoral students trained in psychopathology and supervised by a clinical psychologist. Scores on the 18 ADHD symptoms based on DSM-IV, were coded on a 3-point scale (not present, sub-threshold, or present with impairment) and summed to obtain an overall score with higher scores indicating greater severity. Cronbach’s alphas at BL, F1, F2, and F3 were .96, .95, .94, and .94 respectively.
