Regional brain and ventricular volumes in Tourette syndrome

Background: The pathophysiology of Tourette syndrome (TS) is thought to involve disturbances in corticostriato-thalamo-cortical circuitry. The morphological characteristics of the cortical and associated white matter portions of these circuits have not been previously examined in TS subjects. Methods: High-resolution anatomical magnetic resonance images were acquired in 155 TS and 131 healthy children and adults. The cerebrums and ventricles were isolated and then parcellated into subregions using standard anatomical landmarks. Results: For analyses that included both children and adults, TS subjects were found to have larger volumes in dorsal prefrontal regions, larger volumes in parietooccipital regions, and smaller inferior occipital volumes. Significant inverse associations of cerebral volumes with age were seen in TS subjects that were not seen in healthy controls. Sex differences in the parieto-occipital regions of healthy subjects were diminished in the TS group. The age-related findings were most prominent in TS children, whereas the diminished sex differences were most prominent in TS adults. Group differences in regional ventricular volumes were less prominent than in the cerebrum. Regional cerebral volumes were significantly associated with the severity of tic symptoms in orbitofrontal, midtemporal, and parieto-occipital regions. Conclusions: Broadly distributed cortical systems are involved in the pathophysiology of TS. Developmental processes, sexual dimorphisms, and compensatory responses in these cortical regions may help to modulate the course and severity of tic symptoms.