Striatal dopamine D₂ receptor availability in OCD with and without comorbid social anxiety disorder: Preliminary findings

Dopamine D₂ receptor availability in the striatum has been reported to be low in generalized social anxiety disorder (GSAD) and obsessive-compulsive disorder (OCD), but it has not been studied in persons with comorbid OCD and GSAD (OCD+GSAD). D₂ receptor availability was assessed in 7 subjects with OCD+ GSAD, 8 with OCD, and 7 matched healthy comparison (HC) subjects, all unmedicated adults. D₂ receptor availability was assessed with single-photon emission computerized tomography (SPECT) to measure binding potential (BP) of the D₂ receptor radiotracer [¹²³I] iodobenzamide ([¹²³I]IBZM). Mean striatal [¹²³I]IBZM BP was significantly lower in the OCD+GSAD group (72.58 mL/g, SD = 18.17) than in the HC group (118.41 mL/g, SD = 45.40; P = .025). Mean BP in the OCD group (93.08mL/g, SD = 36.90) did not differ significantly from the HC group (P = .247). Trait detachment, as measured by the Detachment subscale of the Karolinska Scales of Personality, was negatively correlated with D₂ availability across all subjects (r _s=-.55, P = .013). Comorbid GSAD and OCD may be associated with decreased availability of D₂ receptors in the striatum, consistent with prior findings in GSAD. Prior findings of decreased D₂ receptor availability in noncomorbid OCD were not confirmed. Decreased D₂ receptor availability was also associated with trait detachment, supporting prior findings in samples of healthy subjects.