Reduced striatal dopamine D_2/3 receptor availability in Body Dysmorphic Disorder

Though the dopaminergic system is implicated in Obsessive Compulsive and Related Disorders (OCRD), the dopaminergic system has never been investigated in-vivo in Body Dysmorphic Disorder (BDD). In line with consistent findings of reduced striatal dopamine D_2/3 receptor availability in Obsessive Compulsive Disorder (OCD), we hypothesized that the dopamine D_2/3 receptor availability in the striatum will be lower in patients with BDD in comparison to healthy subjects. Striatal dopamine D_2/3 receptor Binding Potential (BP_ND) was examined in 12 drug-free BDD patients and 12 control subjects pairwise matched by age, sex, and handedness using [¹²³I]iodobenzamide Single Photon Emission Computed Tomography (SPECT; bolus/constant infusion technique). Regions of interest were the caudate nucleus and the putamen. BP_ND was calculated as the ratio of specific striatal to binding in the occipital cortex (representing nonspecific binding).Compared to controls, dopamine D_2/3 receptor BP_ND was significantly lower in BDD, both in the putamen (p=0.017) and caudate nucleus (p=0.022).This study provides the first evidence of a disturbed dopaminergic system in BDD patients. Although previously BDD was classified as a separate disorder (somatoform disorder), our findings give pathophysiological support for the recent reclassification of BDD to the OCRD in DSM-5.