A systematic review of diffusion tensor imaging studies in drug-naïve OCD patients before and after pharmacotherapy.

BACKGROUND: Obsessive-compulsive disorder (OCD) is difficult to treat. Studies have shown associations of white matter pathology in OCD, as well as various other psychiatric illnesses, using diffusion tensor imaging (DTI). We conducted a systematic review of controlled studies on drugnaïve patients with OCD vs pharmacologically treated patients with OCD to examine whether pharmacotherapy exerts changes on white matter in OCD. METHODS: A search was conducted to identify controlled trials published from January 2010 to July 2018. All studies used DTI to assess for white matter volume in drug-naïve patients with OCD, pharmacologically treated patients with OCD, and healthy controls. RESULTS: Three studies met the criteria for inclusion. The findings of one study suggest that selective serotonin reuptake inhibitors do exert some changes on white matter, some of which appear to reverse abnormalities noted in the fronto-striato-thalamo-cortical pathways. In another study, no differences in white matter parameters were found between drug-naïve patients vs healthy controls. In a third study, high fractional anisotropy in the splenium correlated with a greater severity of OCD. CONCLUSIONS: Our systematic review suggests mixed results regarding whether drug-naïve patients with OCD have a difference in white matter compared with pharmacologically treated patients with OCD, and whether patients with OCD have a difference in white matter compared with healthy controls.