Functional effects of the DAT1 polymorphism on EEG measures in ADHD

OBJECTIVE: This paper examines whether dopamine transporter gene (DAT1) allele status mediates medication-related change in cognitive and neurophysiological measures among children with attention-deficiency/hyperactivity disorder (ADHD). METHOD: A single 10-mg dose of methylphenidate was given in a double-blind, placebo-controlled fashion to children with ADHD who were seen for cognitive testing and EEG recording. Buccal samples were obtained and genotyped for the DAT1 polymorphism. RESULTS: DAT1 allele status was associated with performance on a sustained attention task and medication-related EEG changes. Compared with those with one or more copies of the DAT1 9-repeat allele (9R), children with two copies of the 10-repeat allele (10R) exhibited poorer performance on the vigilance task. In addition, children with 10R exhibited medication-related EEG changes of increased central and parietal beta power, decreased right frontal theta power, and lower theta/beta ratios; 9R carriers showed the opposite pattern. CONCLUSIONS: The data suggest that the DAT1 polymorphism mediates medication-related changes in cortical activity among children with ADHD.