Increased striatal dopamine transporter in adult patients with attention deficit hyperactivity disorder: effects of methylphenidate as measured by single photon emission computed tomography

Ten previously untreated adults with attention deficit hyperactivity disorder (ADHD) were investigated before and after 4 weeks of treatment with a dose of 3x5 mg methylphenidate/d by single photon emission computed tomography (SPECT) with [Tc-99m]TRODAT-1, the first Tc-99m labelled SPECT ligand specifically binding to the dopamine transporter (DAT). For semiquantitative evaluation of the DAT, specific binding ([STR-BKG]/BKG) was calculated in the striatum (STR) with the cerebellum used as background (BKG). The patients with ADHD presented with increased specific binding of Tc-99m-TRODAT-1 to the DAT as compared with age and sex matched controls ([STR-BKG]/BKG 1.43 +/- 0.18 vs. 1.22 +/- 0.05, P < 0.001). After treatment with methylphenidate specific binding decreased in all patients ([STR-BKG]/BKG 1.02 +/- 0.23, P < 0.001). Thus, for the first time it could be demonstrated using SPECT that methylphenidate lowers increased striatal DAT availability in adults suffering from ADHD. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.