Increased neurokinin-1 receptor availability in the amygdala in social anxiety disorder: a positron emission tomography study with [(11)C]GR205171

The neurokinin-1 (NK1) receptor is abundantly expressed in the fear circuitry of the brain, including the amygdala, where it modulates stress and anxiety. Despite its proposed involvement in psychopathology, only a few studies of NK1 receptor availability in human subjects with anxiety disorders exist. Here, we compared NK1 receptor availability in patients with social anxiety disorder (SAD; n=17) and healthy controls (n=17) using positron emission tomography and the radiotracer [(11)C]GR205171. The Patlak Graphical plot using a cerebellar reference region was used to model the influx parameter, K(i) measuring NK1 receptor availability. Voxel-wise statistical parametric mapping analyses revealed increased NK1 receptor availability specifically in the right amygdala in SAD patients relative to controls. Thus, we demonstrate that exaggerated social anxiety is related to enhanced NK1 receptor availability in the amygdala. This finding supports the contribution of NK1 receptors not only in animal models of stress and anxiety but also in humans with anxiety disorders.