Lower striatal dopamine D_2/3receptor availability in obsessive-compulsive disorder: A meta-analysis of [¹¹C]-raclopride and [¹²³I]-IBZM studies

It is unclear whether striatal dopamine D_2/3 receptor (D_2/3R) availability is reduced in obsessive-compulsive disorder (OCD). We conducted a meta-analysis of substituted benzamide radiotracer studies to address this question (k = 4; N = 33 medication-free patients with OCD and N = 38 matched healthy controls). Our meta-analysis suggests that striatal D_2/3R availability is lower in medication-free patients with OCD compared to healthy controls (Cohen's d = 0.97, 95% CI = 0.45–1.50, z = 3.65, I² = 0, p <.0001). Previous studies have not been sufficiently powered to detect this observed effect-size. We recommend that future studies employ larger sample sizes (n ≥ 19 per group), composed of younger OCD patients with greater illness severity, to validate the findings of this meta-analysis. We hope these findings will help guide future dopamine imaging studies in OCD.