Four years later, Plumlee saw a "60 Minutes" news program in which the key expert witness since hired for her case, Irving Kirsch, said his research on antidepressants indicated most improvement in depressed patients was from the placebo effect.

WSJ: Pfizer disputes suit claiming Zoloft doesn't work

One conclusion emerging from the research, says Irving Kirsch, a professor at Harvard Medical School who wrote the preface to the volume, is that the effect is strongest for those disorders that are predominantly mental and subjective, a conclusion backed by a meta-analysis of placebo studies that was carried out in 2010 by researchers at the Cochrane Collaboration, an organisation that reviews evidence for medical treatments.

ECONOMIST: Alternative medicine: Think yourself better | The