Influence of Light Exposure on Cerebral MAO-A in Seasonal Affective Disorder and Healthy Controls Measured by PET

Inclusion Criteria for Patients: * DSM-IV diagnosis of SAD established by diagnostic interview according to the SCID. * Global Seasonality Score of 10 or higher on the Seasonal Pattern Assessment Questionnaire (SPAQ) * Somatic health based on history, physical examination, ECG, and laboratory screening * Aged 18 to 55 years * No therapeutic treatment of SAD in the last 6 months (drugs and light therapy) * Willingness and competence to complete the informed consent process Inclusion criteria for healthy controls: * Aged 18 to 55 years * Somatic and psychiatric health based on history, physical examination, ECG, laboratory screening, SCID * Willingness and competence to complete the informed consent process Exclusion criteria for patients and healthy controls: * Concomitant major medical or neurological illness * Concomitant psychiatric disorders * Current smoking * Ingestion of antidepressants or other psychotropic agents targeting the serotonergic system, within the last 6 months. * Bright light therapy within the last 6 months. * Current substance abuse including alcohol, drugs of abuse, or any medication in a manner which is indicative of substance-related disorders (e.g. substance dependency) according to the DSM-IV. * Failure to comply with the study protocol or follow the instructions of the investigators. * Positive urine pregnancy test. * For participants who participated in an earlier neuroimaging study using ionizing radiation, the total radiation exposure dose …