Placebo Effect May Not Be Purely Psychological

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The placebo effect is a measurable, observable, or felt improvement in health or behavior not attributable to a medication or invasive treatment that has been administered. Placebo is Latin for “I shall please” and describes a pharmacologically inert substance, such as saline or a sugar pill, that produces an effect that is similar to that which would be expected of an active substance.

H.K. Beecher, who conducted several clinical trials and found that 35% of over 1,000 patients were relieved by a placebo alone, discovered the placebo effect in 1955. Since that time, researchers have attempted to find the reason why the phenomenon occurs and if it was a psychological effect or a physical response. Researchers in Germany think they have found the answer.

Dr. Falk Eippert and colleagues from the University Medical Center Hamburg-Eppendorf studied 15 healthy male volunteers. Heat was applied to their arms to cause pain. The participants were then given one of two creams for the pain – one was an effective painkiller (lidocaine) and the other was an inactive cream. The participants reported experiencing less pain in the areas that were treated with what they believed to be the pain reliever. MRI scans of their spinal cords verified reduced signs of pain-related activity.

It is believed that when patients expect a treatment to be effective, the brain causes a release of natural endorphins that send instructions down the spinal cord to suppress incoming pain signals. The pain is relieved whether or not the treatment was real or a placebo. The effect is similar to the action of opiod drugs such as morphine.

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In 2003, scientists at the University of Turin Medical School in Italy discovered that the placebo effect likely consists of two components. The first is called the expectation effect where the body releases natural opiod-like substances in response to an expected treatment outcome. The other is a conditioned effect, which works because the body or mind is conditioned, sometimes subconsciously, to respond in a certain manner to a procedure.

Placebos are used in many areas of medicine, including alleviating pain, depression, anxiety, Parkinson’s disease, inflammatory disorders and even cancer.

Dr. Eippert’s study is published online in the October 16th issue of the journal Science.

References:

1. "Direct Evidence for Spinal Cord Involvement in Placebo Analgesia."
Falk Eippert, Jürgen Finsterbusch, Ulrike Bingel, Christian Büchel.
Science, 2009, Vol. 326. no. 5951, p. 404.
2. “Placebo Effect: A Cure in the Mind”

Maj-Britt Niemi, Scientific American Mind, February 2009

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