Brain morphometry in Tourette's syndrome: The influence of comorbid attention-deficit/hyperactivity disorder

Three separate groups, using MRI, have reported basal ganglia abnormalities in Tourette's syndrome (TS). We found similar abnormalities in boys with attention-deficit/hyperactivity disorder (ADHD). Because TS and ADHD are frequently comorbid, we contrasted ADHD boys with and without TS along with control subjects. As expected, we found a significant loss of the normal globus pallidus asymmetry in the patients, but presence or absence of TS did not differentiate the ADHD groups. We conclude that accounting for ADHD comorbidity will be important in future TS morphometric studies.