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Genes May Make 'Placebo Effect' Stronger for Some, Study Says
But more questions than answers exist at this point
By Randy Dotinga
MONDAY, April 13, 2015 (HealthDay News) -- A new report suggests that the strength of your "placebo effect" may depend on your particular DNA.
In clinical trials of new drugs, people who receive a fake treatment, or placebo, often feel relief from medical conditions and pain. A better understanding of this phenomenon -- called the placebo effect -- could improve medical research and health care, the authors of the new paper said.
"Placebo responses are emerging as a legitimate series of biological reactions," according to background notes in the study.
"Genetics is involved," said report lead author Kathryn Hall, a research fellow in integrative medicine at Beth Israel Deaconess Medical Center and Harvard Medical School in Boston.
"We need to decipher the genetic signatures that make some people more or less likely to have a beneficial response," said Hall.
Also, "we need a discussion in the medical and patient community on how such genetic information should be used," she added.
For this report, published online April 13 in Trends in Molecular Medicine, Hall's team reviewed what's known about placebo responsiveness and what pitfalls might arise as research continues.
Already, Hall said, "we are finding that if presented in a positive context, patients benefit from placebo treatment even when they know it's a placebo."
And even when given a real drug, it seems to matter whether people know they're taking it. Research has suggested that morphine has a more powerful effect in people who see it administered, Hall said.
Scientists believe the placebo effect involves the release of dopamine, a brain chemical that's most connected to pleasure but also how you move, said Dr. Alberto Espay, director of the Gardner Center for Parkinson's Disease and Movement Disorders at the University of Cincinnati.
The key appears to be the genes that carry the blueprint for dopamine and other chemical pathways in the brain, Hall said. These pathways affect how your mind deals with sensations and symptoms.
"We are learning that the natural variation in the genes ... can confer varying levels of placebo response," she said.
As research on the "placebome" -- genomic effects on placebo response -- advances, many questions will arise, some of them practical, some ethical, the report indicates.
Should patients undergo genetic screens for placebo responsiveness? And how should the results be handled? Should these patients be barred from clinical trials?
There are other questions as well, said Hall: "Is a doctor allowed to lower or increase dosages of pharmaceuticals based on genetic profiles? How should randomized, controlled trials be designed if this information were available?"
Medical studies that involve placebos may need rethinking. These studies typically assume that a drug works if it's more effective than, say, a sugar pill. But Hall said it's possible that "genetic variation modifies the response to placebo and, in some cases the response to drug." This may lead researchers to overestimate or underestimate how well a drug works.
Some wonder if clinical trials should include a no-treatment arm in addition to the treatment and placebo ("control") arms?
"As we strive to develop precision medicine, we can't neglect the importance of the variability of placebo responses in people," Hall said.
Espay, who noted that the new report is useful, said he looks forward to more research that examines how placebos may boost the power of actual medication.
Instead of one or the other -- placebo or real drug -- "how about placebo buttressing the effect of the drug?" he asked.
"Patients could get the additive effects of stronger placebo and the intended pharmacological action of a given therapy," he suggested.
For more on the placebo effect, see the American Cancer Society.
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