Dopamine transporter binding in Gilles de la Tourette syndrome

Preliminary studies in patients with Gilles de la Tourette syndrome (TS) provided evidence of presynaptic dopaminergic dysfunction, demonstrating increased reuptake sites. Therefore we investigated striatal dopamine transporter binding in 12 TS patients and 9 control subjects using single photon emission computed tomography and I-123-labeled 2 beta-carbomethoxy-3 beta-(4-iodophenyl)tropane. In TS patients we found significantly higher relative striatal activity ratios (mean +/-SD 12.33+/-3.58) than in controls (9.36+/-1.35, P < 0.05). Only five patients, however, showed striatum/occipital cortex ratios more than 2 SD above the normal means. Seven patients had activity ratios within the average ratio of the control group plus 2 SD. Regarding the relationship between clinical parameters and striatum/occipital cortex ratios, we found an association between binding ratios and self-injurious behavior and lack of impulse control. This study corroborates previous data suggesting an involvement of the dopaminergic system in TS pathology. Our results demonstrate that an increase in dopamine transporter capacity is a possible but not a necessary alteration, and which appears more likely when self-injurious behavior and lack of impulse control are associated.