The power of placebo

Lydia Marvin writes.

Our understanding of the placebo effect continues to evolve. Jeffrey Mogil, director of the pain-genetics lab at McGill University, discovered that placebos have become 18 per cent more effective in the United States over the past two decades. Found only in the United States, his hypothesis is that direct consumer advertising for drugs allowed in America increases expectations of benefits of drugs. The larger and longer the trial, the greater the placebo effect. Mogil says we need to investigate elements of more powerful placebo response in the US and incorporate those into patient care. More details about Mogil’s study can be found at

Traditionally limited to symptoms originating in the central nervous system, placebos work because hope and trust can trigger release of ‘feel-good’ chemicals in the brain. Drugs that block the action of psychologically induced euphoric neurotransmitters stop the placebo effect. Placebos can be as effective as medication for pain management, stress-related insomnia, and cancer treatment side effects like fatigue and nausea. Recent research on pharmacological conditioning is challenging the restriction of the placebo effect to psychological benefits. This is a type of classical conditioning in which a placebo response is paired with an active medication. Qualities of the drug and the environment of administration are neutral stimuli that are paired with the medication, the unconditioned stimulus. With repetition, the body learns to link the neutral sensory stimuli with the active drug. The medication’s therapeutic effect can be triggered by physical qualities: shape, colour, packaging, smell, and the context of its use: administration by a medical professional in a white lab coat. Drugs exert their effect through biochemical modulation, and the brain can be trained to create a biochemical response identical to the active drug. The brain learns to associate environmental factors with the medication, and these stimuli can then trigger the mechanism of the medication in the brain. Further details about pharmacological conditioning and placebo research can be found in Luana Collaca’s 2019 publication, ‘The Placebo Effect in Pain Therapies’.

An implication for pharmacological conditioning is reducing the amount of noxious medication required. In theory, a wide range of diseases should be susceptible, and this is a promising tool in healthcare.

However, Descartes’ idea that the mind and body are distinct, separable entities is the foundation for our Western biomedical model. The current system takes a reductionist stance, focusing intently on one bodily part at a time. Patients have multiple providers, each comfortable only within their area of competency. Psychologists deal with the intangible matters of the mind, and MDs deal with the anatomical parts. Despite research demonstrating that pharmacological conditioning is possible and promising, application would require blending the field of psychology and standardized medical care. Until the theoretical framework of the medical system changes, I doubt the power of the placebo effect will be fully harnessed.

Lydia Marvin
PsyD student
George Fox University

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