"Stopping Substance Abuse before treating Depression" Dr. Fieve: "40 to 50 % of major depressive disorder patients, have a drug or alcohol history. So I like to get a drug screen if I suspect that. It's a urine drug test, and that says a lot. The drugs that you see are the whole gamut. Psychedelic drugs, pot, cocaine, methadone, heroin, alcohol, barbiturates. That's a very dangerous thing to have ancillary drugs of abuse in the patient that you're examining for depression, You've gotta get them off of that before you can treat the depression effectively with an anti-depressant drug."