Magnetic Resonance Spectroscopy (MRS) in Midlife Depression

Inclusion Criteria for Participants with Depression: * Willing and able to give written informed consent * Meet criteria for Major Depression per DSM-V criteria using Structured Clinical Interview for DSM-V (SCID-V) and a score ≧18 on the 17-item Hamilton Rating Scale for Depression (HAMD). * Absence of significant suicidal ideation, determined by the Columbia Suicide Severity Rating Scale - Screen Version (CSSRS) * Meets MRI scanning safety requirements: * Absence of embedded MR-unsafe metallic objects * Location and quantity of MR-safe metallic objects will minimally impact rigor/reproducibility standards of the MR data (as determined by the PI in consultation with the neuroimaging team) Specific Inclusion Criteria for Controls: * Criteria for major depression not met per the SCID-V * HAMD scores ≦7 * Absence of any Axis I pathology Exclusion Criteria: * Unstable cardiovascular, endocrinologic, hematologic, hepatic, renal, or neurologic disease as evidenced by any of the following: * Clinically significant abnormalities in lab values, medical history and physical exam as determined by PI or their designee * Changes in medications prescribed for chronic medical illnesses within past 4 weeks, * Hospitalization or drastic medical changes within past 4 weeks * Cognitive impairment as defined by: * Score of \< 28 on Mini-mental exam (MMSE) * Below 8th grade reading ability as defined by Wide Range Achievement Test-3 (WRAT3) score * Presence of psychosis (lifetime) / mania (current) as defined by: * Lifetime diagnosis of psychotic disorders SCID-V * SCID-V criteria for current mania/hypomania within the current episode * Clinically significant substance abuse within the past 6 months as defined by meeting the SCID-V threshold of severity for \> 4/11 criteria for substance abuse disorder * Presence of active symptoms of an eating disorder as defined by: * SCID-V diagnosis of Anorexia or bulimia nervosa. * Binge eating and/or purging behavior in the absence of mood alterations or precipitating stress (bingeing within the current episode of mood symptoms will not be exclusionary) * Presence of significant psychiatric comorbidities during current episode: * Primary diagnosis of anxiety-spectrum disorders (panic, generalized anxiety, social phobia etc.), PTSD, OCD based on SCID-V criteria * Severity of above diagnoses exceeds that of major depression based on assessments by the PI and the Study Team members * Severe Axis II personality pathology as determined by a clinician * Use of immune-active medications: * Continuous use of prescribed, standard dose non-steroidal anti-inflammatory (NSAIDs) excluding 81 mg of aspirin within past 1 week and PRN use of NSAIDs within past 72 hours * Intake of antibiotics within the past 2 weeks * Immunization (including seasonal flu) within the past 2 weeks * Use of topical or inhaled steroids within 72 hours unless otherwise approved by PI * Use of systemic steroids (oral or parenteral) within past 6 months * Patients taking herbal supplements with currently known effects on immune system including omega-3 supplements within 2 weeks or probiotics prior to research blood draws and scan unless approved by PI. * Use of psychotropics: * Daily intake of standard doses of antidepressants, mood stabilizers, antipsychotics, psychostimulants within 2 weeks (8 weeks for fluoxetine) prior to initiation of study procedures (scan and research blood sampling) * Daily/clinically significant use of sedative-hypnotics and tranquilizers and opiates as determined by PI * PRN use of sedative/hypnotics, benzodiazepines exceeding equivalent of clonazepam 1mg within 48 hours of study visit. * Cancer and autoimmunity: * Life time history of diagnosis and/or treatment of cancers other than basal cell carcinoma * Life time history of diagnosis and/or treatment of autoimmune disorders including but not restricted to multiple sclerosis, inflammatory bowel disease, systemic lupus erythematosus, rheumatoid arthritis, and Hashimoto's thyroiditis