Are prayer experiments legitimate? Twenty criticisms

The idea that conscious intentions, in the form of prayer, can affect living organisms is an ancient and universal belief spanning ideology, religion, culture, and race. Anthropologist Stephan A. Schwartz states, "The shamanic cave art of Altamira, Tres Freres, and Lascaux presents compelling testimony that our genetic forebears had a complex view of spiritual and physical renewal, one that has survived to the present unchanged in at least one fundamental respect. The intent to heal, either oneself or another, whether expressed as God, a force, an energy, or one of many gods, has consistently been believed to be capable of producing a therapeutic result."1. In the past 2 decades, this ubiquitous belief has been increasingly subjected to scientific scrutiny. In 1988, cardiologist Randolph C. Byrd, of UC-San Francisco School of Medicine, published the first randomized controlled trial (RCT) involving distant intercessory prayer.2 Since then, investigators have continued to explore in controlled trials the possible effects of remote prayer and healing intentions in coronary heart disease,3-5 AIDS,6 infertility,7 and other clinical conditions.8, 9. Prayer research did not originate with Byrd's provocative study, however. Numerous controlled experiments exploring prayer and distant healing have been done in nonhuman subjects since the 1960s. Significant among them is a series of experiments by psychologist Bernard R. Grad, of McGill University. Grad explored the influence of healing intentions on the rate of healing of surgical wounds in animals, the growth rate of animal tumors, and the rate of growth of plants and microbes.10-16 Similar results were obtained by successive investigators building on his methods.17-20 Succeeding studies involved increasingly objectifiable end points, such as the rate of hemolysis of red blood cells21 and the kinetics of specific biochemical reactions.22, 23 Experiments in nonhuman subjects are important because they eliminate the placebo effect, one of the most common objections lodged against human studies. Of the eight major controlled clinical trials of prayer and distant healing in humans that have been published to date, four have yielded statistically significant results. Both the human and nonhuman studies in distant healing have been the subjects of recent reviews and systematic and metaanalyses.24-35 All but one31 of the systematic and metaanalyses of the human experiments in prayer and distant healing that have been published to date have been generally positive, and even this review concluded that the evidence, although inconclusive, was interesting enough to justify further study. A variety of objections to prayer experiments have understandably been raised. We will comment on the most common of them. © 2005 Elsevier Inc. All rights reserved.