Does Serotonin Help In Treating Depression Effectively Compared To Selenium?

what is betterwhat is better for depression selenium or serotonin? I have been taking selenium for 2 months, it has helped a lot. My Dr. said if it didn t help try Serotonin 100mg./3 times a day. Even though the selenium has helped I was wondering if the serotonin would help even more? Thank you for answering my questions