Prediction of response to methylphenidate among children with ADHD and mental retardation

The primary purpose of this study was to predict stimulant medication response among children with attention-deficit hyperactivity disorder (ADHD) and mental retardation (MR).

Forty-seven children with ADHD and MR (IQs of 48 to 77) served as subjects; ages ranged from 6.1 to 12.5 years. Subjects participated in a double-blind, placebo-controlled study of two doses of methylphenidate (0.3 and 0.6 mg/kg per dose) and a placebo. Data were collected in each child's weekday classroom and a Saturday laboratory classroom. Stepwise multiple regression analyses were used to predict drug responses in both settings.

Higher parent ratings of impulsivity and activity level at baseline were associated with greater gains in weekday classroom dependent measures. Similarly, higher weekday teacher measures of activity level, impulsivity, inattention, and conduct problems at baseline were related to improvement on Saturday laboratory classroom dependent measures. Finally, gender, race, and socioeconomic status (SES) were found to be important predictors, with males, Caucasian subjects, and subjects from families of higher SES more likely to evidence clinical gains on a number of variables than other subjects.

These results were generally consistent with research conducted among children with ADHD but without MR. However, factors such as race and conduct problems appear to have predictive utility specific to children with MR.