Our expectations form some part of our response to any health care treatment. Dr. Kirsch calls this part the placebo effect. How important is it? Kirsch expected the placebo effect to be more important for some treatments than for others. He chose depression as the condition most likely to show a strong placebo response.
Kirsch examined the clinical trial data, and found that the placebo effect can easily account for 100% of patients' response to antidepressants. These drugs outperform sugar pills in clinical trials, but only by a small amount, and perhaps only because their side effects are so obvious that participants know when they're getting the real drug.
Everyone who is considering antidepressants should read this to understand their treatment options. Psychotherapy, exercise, and herbal treatments are effective without the side effects of drugs.