Abnormal peripheral benzodiazepine receptor density associated with generalized social phobia

Background: Peripheral benzodiazepine receptors (PBRs) are involved in regulating stress responses. Abnormally low numbers of platelet PBRs have been found in patients with panic disorder, posttraumatic stress disorder, and generalized anxiety disorder, but not in patients with obsessive-compulsive disorder (OCD) or major depressive disorder (MDD). The purpose of this study was to evaluate the PBR density on platelets from patients with generalized social phobia (GSP). Methods: The density (Bmax) and dissociation constant (Kd) of platelet PBRs was determined for 53 medication-free patients with GSP and an equal number of control subjects (NC). Results: The GSP group was found to have a significantly lower PBR Bmax than the NC group (GSF = 2764 ± 1242 vs. NC = 4327 ± 1850 fmol/mg protein, df = 1,100, F = 22.7, p = .00001). Conclusions: GSP shares this PBR abnormality with some other anxiety disorders but not with OCD or MDD. PBRs may play a role in the pathophysiology of some anxiety disorders.