Tuesday, April 14, 2015

The placebome: Where genetics and the placebo effect meet

Genetic sequencing is revealing that the placebo response is actually a complex phenotype. The study of genomic effects on the placebo response, referred to as “the placebome”, has yielded ample evidence that genetic variations in the brain’s neurotransmitter pathways modify placebo effect. The placebo effect occurs when patients show improvement from treatments that contain no active ingredients. Scientists initially used behavioral instruments such as personality measures to predict which patients would respond to placebos. Over the past decade, the development of neuroimaging technologies illuminated the activation of the brain's neurotransmitter pathways in response to placebos. Because they are the chemical messengers that either excite or inhibit nerve function in the brain, many neurotransmitters play key roles in reward and pain. Researchers from Beth Israel Deaconess Medical Center have hypothesized that genetic variation in the genes that encode the proteins in these neurotransmitter pathways might also modify placebo responses. In 2012 the first placebo biomarker, catechol-O-methyltransferase (COMT), was identified by Kathryn T. Hall. Genetic variations in the COMT gene influences the brain’s levels of the neurotransmitter dopamine which also determined the extent of an individual’s placebo response. Researchers reviewed scientific literature over the last 10 years and were provided with confirmation that, beyond the COMT gene, there is evidence for genetic variation in other neurotransmitter pathways that modify placebo response.
This research suggests that the assumptions of placebo controls in randomized clinical trials need to be reconsidered. The next step in describing the placebome would be to include a no-treatment control in placebo-controlled randomized clinical trials. I found this article to be interesting as it sheds new light on what is known about the placebo effect. I’m curious to see how further research on this topic effects clinical trials and the use of placebos.

http://www.sciencedaily.com/releases/2015/04/150413140906.htm


http://www.webmd.com/pain-management/what-is-the-placebo-effect

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