Study sheds light on genes' role in methylphenidate treatment response.(ADHD)(Clinical report)

A new study suggests that polymorphisms in the dopamine transporter (DAT) gene and the dopamine receptor D4 (DRD4) have an effect on dose response to methylphenidate in the treatment of attention-deficit/hyperactivity disorder (ADHD). The findings, published online Sept. 15 in the Journal of the American Academy of Child and Adolescent Psychiatry, are considered important because unlike in many previous studies, this study had a placebo-controlled design and took into account teacher ratings of children's outcomes as well as parent ratings.

With stimulant treatment response varying considerably, and with the field lacking consistent predictors of response, much research attention in the past decade has focused on genetics' role as a possible predictor. The most studied area to date has been the role of polymorphisms in the dopamine transporter, since DAT inhibition constitutes a major mechanism of action for methylphenidate. Yet results to date have been mixed, and most of the studies have not been placebo-controlled, have not included teacher ratings, and have not evaluated response at more than 1 dose of medication.

For the latest study, Tanya E. Froehlich, M.D., assistant professor of …