Increased dopamine transporter density in Parkinson's disease patients with Social Anxiety Disorder.

Social Anxiety Disorder (SAD) is more common among PD patients than in the general population. This association may be explained by psychosocial mechanisms but it is also possible that neurobiological mechanism underlying PD can predispose to SAD. The aim of this study was to investigate a possible dopaminergic mechanism involved in PD patients with SAD, by correlating striatal dopamine transporter binding potential (DAT-BP) with intensity of social anxiety symptoms in PD patients using SPECT with TRODAT-1 as the radiopharmaceutical. Eleven PD patients with generalized SAD and 21 PD patients without SAD were included in this study; groups were matched for age, gender, disease duration and disease severity. SAD diagnosis was determined according to DSM IV criteria assessed with SCID-I and social anxiety symptom severity with the Brief Social Phobia Scale (BSPS). Demographic and clinical data were also collected. DAT-BP was significantly correlated to scores on BSPS for right putamen (r=0.37, p=0.04), left putamen (r=0.43, p=0.02) and left caudate (r=0.39, p=0.03). No significant correlation was found for the right caudate (r=0.23, p=0.21). This finding may reinforce the hypothesis that dopaminergic dysfunction might be implicated in the pathogenesis of social anxiety in PD.