Microstructural brain abnormalities in patients with obsessive-compulsive disorder: diffusion-tensor MR imaging study at 3.0 T.

PURPOSE: To use diffusion-tensor (DT) magnetic resonance (MR) imaging to explore the integrity and connectivity of brain white matter in patients with obsessive-compulsive disorder (OCD) and to correlate DT parameters with clinical measures.
MATERIALS AND METHODS: This study was approved by the local ethical committee, and written informed consent was obtained from all participants. DT imaging was performed by using a 3.0-T MR imager in 23 patients with OCD and 23 healthy control subjects matched for age, sex, education level, and handedness. By using voxel-based analysis, fractional anisotropy (FA) and axial and radial diffusivities were compared between patients and control subjects with a two-sample t test and were tested for correlation with symptom severity, as measured by using the Yale-Brown Obsessive-Compulsive Scale and obsessive-compulsive subscale scores, and with illness duration, as measured by using simple regression in statistical parametric mapping program.
RESULTS: Compared with control subjects, OCD patients demonstrated significantly increased FA in the genu and body of corpus callosum and white matter of right superior frontal gyrus and corpus callosum; no areas of significantly decreased FA were found. For areas of increased FA, axial diffusivity was higher than that in control subjects, while radial diffusivity was not significantly different. The FA values in the white matter of left middle temporal gyrus in OCD patients correlated positively with clinical measures (r = 0.542, P < .001).
CONCLUSION: OCD is associated with axonal microstructural abnormalities within the white matter, which may indicate impaired axonal integrity and increased connectivity. The positive correlation between DT abnormalities and symptom severity suggests that DT imaging may be of clinical value in measuring and following disability in OCD patients.