Oxidative and Nitrosative Stress Markers in Obsessive-Compulsive Disorder: A Systematic Review and Meta-Analysis.

OBJECTIVE: Obsessive-compulsive disorder (OCD) is a chronic, prevalent and highly impairing psychiatric illness. Although the pathophysiology of OCD remains unknown, pathways involved in oxidative and nitrosative stress (O&NS) have been implicated. The present study aims to systematically review the literature for quantitative evidence that patients with OCD have altered measures of blood O&NS markers. METHODS: Independent random-effects meta-analyses using standardized mean differences were conducted to assess each marker separately. Additionally, data from multiple markers were pooled together in a meta-analysis for measures of oxidant activity and another for measures of antioxidant activity. RESULTS: Thirteen studies met inclusion criteria, involving 433 OCD patients and 459 controls. Eleven blood O&NS markers were eligible for independent quantitative analyses. We found that, in OCD patients, the oxidant markers 8-hydroxydeoxyguanosine and malondialdehyde, and the antioxidants glutathione peroxidase and superoxide dismutase, were significantly increased while total antioxidant status, vitamin C and vitamin E were significantly decreased, when comparing with controls. Regarding pooled meta-analyses, we found a statistically significant increase in oxidant markers, but non-significant results regarding antioxidant markers. CONCLUSIONS: Our meta-analysis suggests that OCD patients have a systemic oxidative imbalance that is not adequately buffered by the antioxidant system. Additional studies are needed in order to support this association. This article is protected by copyright. All rights reserved.