A brief history of placebos and clinical trials in psychiatry

Abstract

The history of placebos in psychiatry can be understood only in the context of randomized controlled trials (RCTs). Placebo treatments are as old as medicine itself, and are particularly effective in dealing with psychosomatic symptoms. In psychiatry, placebos have mainly been featured in clinical drug trials. The earliest controlled trial in psychiatry (not involving drugs) occurred in 1922, followed by the first crossover studies during the 1930s. Meanwhile the concept of randomization was developed during the interwar years by British statistician Ronald A Fisher, and introduced in 3 trials of tuberculosis drugs between 1947 and 1951. These classic studies established the RCT as the gold standard in pharmaceutical trials, and its status was cemented during the mid-1950s. Nevertheless, while the placebo became established as a standard measure of drug action, placebo treatments became stigmatized as unethical. This is unfortunate, as they constitute one of the most powerful therapies in psychiatry. In recent years, moreover, the dogma of the placebo-controlled trial as the only acceptable data for drug licensing is also being increasingly discredited. This backlash has had 2 sources: one is the recognition that the US Food and Drug Administration has been too lax in permitting trials controlled with placebos alone, rather than also using an active agent as a test of comparative efficacy. In addition, there is evidence that in the hands of the pharmaceutical industry, the scientific integrity of RCTs themselves has been degraded into a marketing device. The once-powerful placebo is thus threatened with extinction.