White matter abnormalities in OCD correlate with symptom severity

Last Updated: 2008-02-18 7:35:30 -0400 (Reuters Health)

NEW YORK (Reuters Health) – Using diffusion-tensor imaging, Japanese researchers found white matter abnormalities in the corpus callosum of patients with obsessive-compulsive disorder (OCD), as compared with healthy controls, and these abnormalities were correlated to symptom severity.

Dr. Yukiko Saito and colleagues of Kansai Medical University, Osaka, report their research in the February issue of Radiology.

"Our study results," Dr. Saito told Reuters Health, "support the widely held view that the orbital prefrontal region is involved in the pathophysiology of OCD. It is important that the results also indicate that the OFC (orbitofrontal circuit) influences symptom severity in patients with OCD."

The study included 16 OCD patients (mean age, 28.7 years) and 16 healthy volunteers. Findings on diffusion-tensor imaging failed to show any significant between-group differences in mean diffusivity in five subdivisions of the corpus callosum, according to the team.

However, a significant reduction in fractional anisotropy was observed in the rostrum of the corpus callosum in patients with OCD compared with the rostral fractional anisotropy in control subjects without OCD (p < 0.001).

Moreover, higher fractional anisotropy in the rostrum correlated significantly with lower scores on the Yale-Brown Obsessive-Compulsive Scale. "A diffusion-tensor imaging study can be useful as a new predictor of severity of obsessive-compulsive symptoms in addition to the Yale-Brown Obsessive-Compulsive Scale," Dr. Saito told Reuters Health.

"Future studies with larger numbers of drug-naive patients and more complex methods, such as tract tracing for direct examination of the targeted white matter, may help to elucidate the contribution of microstructural white matter changes in the orbitofrontal region to the pathophysiology and outcomes of OCD," the researcher concluded.

Radiology 2008;246:536-542.