Validity of large-deformation high dimensional brain mapping of the basal ganglia in adults with Tourette syndrome.
BACKGROUND Despite strong circumstantial evidence that the pathophysiology of Gilles de la Tourette syndrome (TS) involves structural and functional disturbances of the basal ganglia, inconsistent findings from relatively small in vivo TS imaging studies have supported contradictory conclusions concerning the role of abnormal anatomical characteristics of the basal ganglia in the pathophysiology of TS. METHODS Basal ganglia volumes were measured on high-resolution magnetic resonance images acquired for 154 children and adults with TS and 130 healthy control subjects. Repeated-measures analyses tested hypotheses concerning regional specificity, age effects, and abnormal asymmetries in the basal ganglia of subjects with TS. Subjects with prior neuroleptic exposure had larger basal ganglia volumes and were excluded from further statistical analyses. RESULTS Caudate nucleus volumes were significantly (P =.008) smaller in children and adults with TS. Lenticular nucleus volumes also were smaller in adults with TS and in children with TS who were diagnosed as having comorbid obsessive-compulsive disorder. Regional anatomical asymmetries did not differ across groups. Regional volumes did not correlate significantly with the severity of tic, obsessive-compulsive disorder, or attention-deficit/hyperactivity disorder symptoms. CONCLUSIONS Reduced caudate nucleus volumes may be a good candidate marker for a trait abnormality in the structure of the basal ganglia in persons with TS. Smaller lenticular nucleus volumes may be an additional marker for the presence of comorbid obsessive-compulsive disorder and for the persistence of tic symptoms into adulthood. Brain regions other than the basal ganglia may have greater clinical relevance in determining the severity of tic symptoms.