 The purpose of this study is to evaluate the feasibility of developing a microbiome probe of depression and to evaluate the microbiome change in a preliminary analysis of treatment response n20 vs. non response n20 to the antidepressant citalopram. This study is a 12 week open trial that will enroll approximately 80 participants anticipated 40 study completers with paired biomarker data with an episode of major depression, Bipolar I or Bipolar II and 40 age- and sex-matched healthy controls. 