Results from positron emission tomography scans indicate patients with social anxiety disorder have invariably increased serotonin synthesis and transporter availability compared with healthy patients. Researchers used positron emission tomography (PET) to assess serotonin synthesis and serotonin transporter availability among 18 patients with social anxiety disorder (mean age, 32.6 years) and 18 healthy patients (mean age, 34.7 years). {read more here}