Regional cerebral blood flow in obsessive-compulsive patients with and without a chronic tic disorder. A SPECT study

The main goal of the present study was to explore whether regional cerebral blood flow (rCBF) differs between obsessive-compulsive disorder (OCD) patients without chronic motor tic disorder and those OCD patients with a comorbid chronic tic disorder. Twenty-seven patients suffering from OCD (DSM-IV criteria), including 7 OCD patients who met DSM-IV criteria for simple chronic motor dic disorder, and 16 healthy volunteers were examined at rest using a high resolution SPECT. Seven regions of interest (ROIs) were manually traced and quantified as a percentage of the mean cerebellar uptake. Severity of obsessive-compulsive symptoms (OCS), anxiety and depressive symptoms and presence of motor tics were assessed with the Y-BOCS, HRS-A, HRS-D, MADRS, and Yale Global Tics Severity Scale, respectively. We found a significant relative decrease in rCBF in OCD patients without motor tics compared to healthy volunteers in the right orbitofrontal cortex (OCD without tics = 0.87; healthy volunteers = 0.94; p = 0.02). No significant differences in rCBF were seen when OCD patients with and without chronic tics were directly compared. A lower severity of OCS in OCD patients with chronic tics was found. These results are consistent with previous functional neuroimaging studies at rest that have widely involved the orbitofrontal cortex in the pathophysiology of the OCD. However, our results do not support the idea that OCD patients with chronic tics may constitute a biological subgroup within the OCD.