Microbiome of Depression & Treatment Response to Citalopram

The study will be conducted at Mayo Clinic Jacksonville Department of Psychiatry (recruit up to 10 patients and 10 controls with paired data) and Mayo Clinic Depression Center in Rochester (recruit up to 30 patients and 30 controls with paired data). Patients with major depression, Bipolar Disorder I or Bipolar Disorder II confirmed by structured diagnostic interview (SCID) and moderate symptom severity (Quick Inventory of Depressive Symptomatology or S-C16) will be enrolled in the 12 week study. We will explore the gut microbiome (and its genetic material) and gut-brain markers of inflammation (cortisol, cytokines) from stool specimens and serum samples, respectively. Collections will be at baseline, week 2, and week 12 of the study. Healthy controls matched for age, sex (including menopausal status of female subjects), and body-mass index (BMI) will have only baseline stool and serum collections. Statistical t-tests will be used to assess baseline differences between patient and controls in microbiome and inflammatory markers. Treatment response (50% reduction in QIDS), treatment remission (QIDS-C16 \< 6) will be analyzed with change in microbiome and inflammation markers. Correlational analysis with multiple testing corrections will be conducted between depression symptom severity and measures of cortisol, cytokines, and gut microbiome composition. This study will focus on early translation of Dr. Fryer and Dr. Chia's research and will bring the gut-brain interface to the field of individualizing treatment to patients who struggle with depression. This project will provide insight into how gut microbiota may be implicated in depression, how antidepressant treatments alter microbiota composition, and how these factors impact key physiologic mediators of depression (i.e. cortisol and cytokine levels). The public health implications of more focused drug development and treatment for depression are substantial.