The Science Behind Prayer And The Placebo Effect


Why does the placebo effect work better than prayer? originally appeared on Quora: the place to gain and share knowledge, empowering people to learn from others and better understand the world.

Answer by Tirumalai Kamala, Immunologist, Ph.D. Mycobacteriology, on Quora:

There is the placebo and there are placebo effects or responses. The placebo, the prototypical sugar pill for example, is an inert treatment with no medicinal value whatsoever that is nevertheless consistently found capable of alleviating medical symptoms such as pain or inflammation in at least a third of patients or even more on average.

However, recent research shows placebos are merely one part of the much larger placebo effects or responses, which span an entire gamut of procedures, substances and rituals ranging from sham surgeries, acupuncture, yoga, chiropractic, massage, homeopathy to specific diets, dietary supplements, herbs to doctor-patient interactions and yes, even prayers.

A 2008 case report (1) on a Huntington’s disease patient is a modern example of the placebo effects of prayer. Huntington’s is one of most devastating and as-yet incurable of conditions. Upon visiting Lourdes in the French Pyrenees, this patient perceived that the Virgin Mary herself spoke to her and told her she was cured. Even as she continued taking her medicines (bromocriptine and sertraline), this patient now resolutely believed she was cured.

In fact, these two neurologists had examined her several times prior to and after her pilgrimage. They found a near complete elimination of dystonia and chorea (involuntary movement) as well as a 40% improvement using a standardized score 1 week and 3 months later, even though there was no genetic cure whatsoever (1). In short, symptom alleviation, not cure. They concluded that this patient’s intense religious conviction mediated its placebo effect on the intensity of some of her movement disorder symptoms by influencing and reducing her anxiety, which is known to increase these symptoms.

Doctors the world over and throughout history have likely experienced at least one such instance of miraculous improvement that couldn’t be explained by the science of the day. That doesn’t necessarily mean they are truly miraculous. Rather, that’s simply an indication of the glaring gap in our knowledge of human biology since placebo effects are now known to influence biochemistry in physiological systems as varied as neurobiology, endocrinology and immunology, the trifecta some now study under the rubric Psychoneuroimmunology.

Placebos and their effects have various definitions (2). A common link among them is the patient’s expectation and perception of some health benefit.

The handful of reasonably well-designed studies on the placebo effects of prayer cautiously conclude it could mediate analgesia (pain relief), working its way perhaps partly through a stronger social support network among the religious or maybe even through the direct influence of specific religious prayers and symbols (3, 4, 5, 6). Exactly how remains an open question.

It sounds reasonable to conclude that patients would engage in prayer with the expectation of health benefit. Thus, rather than placebo versus prayer, prayer itself could be expected to and indeed appears able to mediate the placebo effect in some disease symptoms in some people in some circumstances.

Some symptoms, some people, some circumstances, and therein lies the proverbial elephant-sized problem because we currently lack a thorough biological understanding of how prayer or anything else for that matter mediates placebo effects.

When do placebo effects work? When do they not work? How do they work when they do work? What are their predictable elements? For example, genetic polymorphisms predictive of either adaptive/beneficial placebo responses or maladaptive/harmful nocebo responses. After all, the effect is Janus-faced; as likely to benefit as harm.

Though modern medicine considers placebos and placebo effects or responses an encumbrance or obstacle, an unfortunately short-sighted and counter-productive stance, the reality is that cracking the biochemical and molecular underpinnings of myriad placebos and placebo effects or responses would yield some of the biggest bonanzas in biomedicine, in terms of both knowledge and fortune. After all, they appear to somehow catalyze the body’s self-healing capacity in diverse ailments, anything from chronic inflammatory disorders to even cancers. Figuring out how to trigger this capacity predictably and safely in a personalized manner could, at a minimum, enable dose-sparing of otherwise toxic drugs.


1. Moreno, Jose Luis López‐Sendón, and Justo Garcia de Yebenes. “The impact of an intense religious experience on motor symptoms in Huntington’s disease.” Movement Disorders 24.3 (2009): 473-474.

2. Trimmer, Pete C., and Alasdair I. Houston. “The Ups and Downs of Placebos.” Evolutionary Thinking in Medicine. Springer, Cham, 2016. 357-369. The Ups and Downs of Placebos

3. Wiech, Katja, et al. “An fMRI study measuring analgesia enhanced by religion as a belief system.” Pain 139.2 (2008): 467-476.…

4. Kohls, Nikola, et al. “Spirituality: an overlooked predictor of placebo effects?.” Philosophical Transactions of the Royal Society of London B: Biological Sciences 366.1572 (2011): 1838-1848. Spirituality: an overlooked predictor of placebo effects?

5. Hyland, Michael E. “Motivation and placebos: do different mechanisms occur in different contexts?.” Philosophical Transactions of the Royal Society of London B: Biological Sciences 366.1572 (2011): 1828-1837. Motivation and placebos: do different mechanisms occur in different contexts?

6. Jegindø, Else-Marie Elmholdt, et al. “Expectations contribute to reduced pain levels during prayer in highly religious participants.” Journal of behavioral medicine 36.4 (2013): 413-426. Expectations contribute to reduced pain levels during prayer in highly religious participants

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