Dopamine transporters, D2 receptors, and dopamine release in generalized social anxiety disorder

Dopamine D2 receptor and dopamine transporter (DAT) availability in the striatum (STR) have each been reported abnormal in generalized social anxiety disorder (GSAD) in studies using single photon emission computerized tomography (SPECT). D2 receptors and DAT have not previously been studied within the same GSAD subjects, however, and prior GSAD studies have not assessed dopamine release or subdivided the STR into functional subregions.

Unmedicated adults with GSAD (N=17) and matched healthy comparison (HC) subjects (N=13) participated in this study. Of these, 15 GSAD and 13 HC subjects completed baseline assessment of D2 receptor availability using positron emission tomography (PET) with the radiotracer [11C]raclopride. Twelve GSAD and 13 HC subjects completed a repeat scan after intravenous administration of d-amphetamine to study dopamine release. Twelve of the GSAD subjects and 10 of the HC subjects also completed SPECT with the radiotracer [123I] methyl 3beta-(4-iodophenyl) tropane-2beta-carboxylate ([123I]beta-CIT) to assess DAT availability.

GSAD and HC groups did not differ significantly in striatal DAT availability, the overall striatal or striatal subregion D2 receptor availability at baseline, or change in D(2) receptor availability after d-amphetamine. Receptor availability and change after d-amphetamine were not significantly associated with severity of social anxiety or trait detachment.

These findings do not replicate previous findings of altered striatal DAT and D2 receptor availability in GSAD subjects assessed with SPECT. The differences from results of prior studies may be due to differences in imaging methods or characteristics of samples.