Controversial study questions the value of antidepressants

A controversial study of people being treated for depression concludes that the placebo effect appears to be behind most of the therapeutic impact of antidepressant drugs.

Psychologists Irving Kirsch, PhD, of the University of Connecticut, and Guy Sapirstein, PhD, of Westwood Lodge Hospital in Needham, Mass., conducted a meta-analysis of 19 double-blind clinical trials. Collectively, the studies involved 2,318 patients randomly assigned to one of various psychotropic medications?including such antidepressants as Prozac and Paxil?or to a placebo.

Using a mathematical formula to calculate effect sizes, Kirsch and Sapirstein determined that 75 percent of the patients? response to the medications was a placebo response, and at most, 25 percent was a true drug effect. In fact, they found that patients responded even to the drugs that are not technically considered antidepressants, such as lithium and adinazolam.

'This does not mean that only 25 percent of patients are likely to respond to the pharmacological properties of the drug,' the authors write. 'Rather, it means that for a typical patient, 75 percent of the benefit obtained from the active drug would also have been obtained from an inactive placebo.'

The findings appear in the latest edition of APA?s online journal, Prevention and Treatment (journals.apa.org/prevention/volume1/pre0010002a.html). Journal editor-in-chief and APA President Martin E.P. Seligman, PhD, and associate editor Peter Nathan, PhD, say the study is no doubt controversial because the authors analyzed studies that involved varied groups of participants, types of treatment and statistical methods.

In fact, the editors included critical commentary on the study. For example, psychiatrist Donald Klein, MD, of Columbia University, argues that the meta-analysis is flawed because it 'derives from a miniscule group of unrepresentative, inconsistently and erroneously selected articles arbitrarily analyzed by an obscure, misleading effect size.'

But the editors added that many colleagues reviewed the Kirsch and Saperstein manuscript, and decided it had considerable merit despite its contentious conclusions.

?S. Sleek