Treating depression is guesswork. Psychiatrists are beginning to crack the code.

Here's a frustrating fact for anyone who has been prescribed medication or therapy for depression: Your doctor doesn't know what treatment will work for you. "It is currently complete primitive guesswork," Leanne Maree Williams, a professor at Stanford University, says. "It's hard to imagine how you can do worse than the current situation, to be honest." Depression means being stuck in a chronic state of sad mood or lack of enjoyment in life, to a degree where it starts to degrade quality of life. The two main treatments are cognitive behavioral therapy (CBT), a talk-centered approach that gets patients to readjust their habits, and antidepressant medications.