DPA-714 and FDG PET/MRI in Depression

Inclusion Criteria: 1. For all groups : * No alcohol or psychoactive substances such as coffee had been consumed in the 24 hours prior to the examination * MMSE≥24 points，MOCA≥26 points * No anti-infective drugs in the past 1 month, no cold, fever or other infection history in the past 2 weeks * Patients with diabetes had fasting controlled below 9.0mmol/L before the examination * Volunteer to participate in the study and sign the informed consent 2. For Recurrent depression patients: * Meet the Diagnostic criteria for recurrent major depressive disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) * Age 35-85 years old, gender is not limited * HAMD≥8 points 3. For first episode depression Patients: * Gender, age and education level were matched with the recurrent depression group * Meet the Diagnostic criteria for the first episode of depressive disorder in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-V) * HAMD≥8 points 4. For controls: * Healthy people undergoing "DPA-714 or FDG imaging PET/MRI" physical examination in PET/CT room of our hospital * Gender and education level were consistent with both the recurrent depression group and the first-episode depression group * never used any psychotropic drugs * HAMD\<8 points；HAMA\<7 points Exclusion Criteria(for all groups): * Have a history of organic mental disorders or other mental disorders * A family history of hereditary diseases * Persons with mental retardation or dementia * A history of psychoactive substance abuse * Can not cooperate with/complete the psychological examination scale * Previously found serious physical diseases (heart, brain, liver, lung and kidney) * MRI contraindications, abnormalities found in head CT or MRI * A history of drug or alcohol abuse * Have a history of metabolic diseases such as hyperthyroidism, hypothyroidism,and rheumatic diseases * are in the state of pregnancy or breastfeeding