Neurosteroid Metabolism and the Antidepressant Effects of Serotonin Specific Reuptake Inhibitors (SSRI's)

Following an initial telephone screen to assess inclusion and exclusion criteria, the evaluation will continue with an in-person screening evaluation to assess the presence or absence of active medical history and history of major psychiatric illness, as well as review of the consent document. If found to be eligible, participants would then be admitted to the study.

The next step for eligible, consenting depressed subjects and is a baseline visit. The baseline visit will last up to 3.5 hours. We will begin the baseline visit by collecting a urine sample for a drug (and, for women, pregnancy) test. As long as that is negative, we will then collect a blood sample of about 180 cc. After the blood draw, participants will complete cognitive tests and meet again with the study psychiatrist. Eligible consenting healthy controls will come in for a one time study visit and complete the same tests performed during the depressed subject baseline visit. Both depressed participants and healthy controls will return a stool sample collected at home with a kit given during the screening visit.

After the baseline visit, depressed subjects (but not healthy controls) will begin taking an FDA approved antidepressant, as prescribed by the study psychiatrist, for the next 8 weeks while they are enrolled in the study. The specific drug will be decided upon between the participant and the study psychiatrist at the in-person screening visit.

After 4 weeks, depressed participants will return to UCSF to meet again with the psychiatrist to discuss symptoms and how to continue treatment. They will be given an at home collection kit to return a stool sample at the last study visit.

4 weeks later (after 8 weeks in total), depressed participants will come back for an additional visit that will include the same blood draw and testing as the baseline visit. They also will return their stool sample. A physician-investigator will meet with the depressed subjects to review their clinical responses to treatment and to make further treatment suggestions, which the subjects may use in discussions of their future treatment options with their personal physicians. If a decision is made to discontinue antidepressant treatment, the subjects will be given instructions on how to withdraw from the medication, and will be given up to a 4 week supply of the drug to facilitate this withdrawal.