Prozac, Paxil and Zoloft barely surpassed an inactive placebo in clinical testing when the patient and investigator didn't know who was getting a real drug.

    In many clinical trials for FDA approval the difference between drug and placebo was about 2 points on a 0-50 scale measuring depression.

   In a study of the five popular drugs, more than 80% of the benefit was duplicated in a similar group getting a placebo.