Striatal dopamine D(2) receptor availability in OCD with and without comorbid social anxiety disorder: preliminary findings.

Dopamine D(2) 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). D(2) receptor availability was assessed in 7 subjects with OCD+GSAD, 8 with OCD, and 7 matched healthy comparison (HC) subjects, all unmedicated adults. D(2) receptor availability was assessed with single-photon emission computerized tomography (SPECT) to measure binding potential (BP) of the D(2) receptor radiotracer [(123)I] iodobenzamide ([(123)I]IBZM). Mean striatal [(123)I]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 (93.08 mL/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 D(2) availability across all subjects (r(s)= -.55, P=.013). Comorbid GSAD and OCD may be associated with decreased availability of D(2) receptors in the striatum, consistent with prior findings in GSAD. Prior findings of decreased D(2) receptor availability in noncomorbid OCD were not confirmed. Decreased D(2) receptor availability was also associated with trait detachment, supporting prior findings in samples of healthy subjects.