Genes determine whether sugar pills work

December 3, 2008

It is a well-known fact in drug trials that individuals can respond just as well to placebos, sugar pills, as to the active drug. On the other hand, it is difficult to explain why only certain people get better from placebos. A team of researchers from Uppsala University and Gothenburg University have now found gene variants that can impact the placebo effect and a mechanism in the brain that characterizes those who respond to placebos.

The study, published in Journal of Neuroscience, examined 108 individuals suffering from social phobia using a brain camera (PET, positron emission tomography). The individuals were participating in a treatment study looking into how anxiety-moderating drugs affect brain activity. Just under one fourth of the subjects were given a placebo instead of a drug. This was a double-blind study, meaning that neither the subjects nor the research team know who was taking the drug or the sugar pill.

Before and after an eight-week period of treatment, the participants were asked to give a stressful oral presentation while their brain activity was monitored. When all the metering was finished and the study was decoded, it turned out that 40 percent of the placebo group had received the same degree of anxiety relief from the sugar pill as other groups got from a drug.

Those who responded well to the placebo had a significant reduction in activity in the amygdala in the temporal lobe, while this reduction was not found in the others. In previous research the amygdala has stood out as a key structure for emotional reactions. Both serotonin-active drugs (SSRI preparations) and cognitive behavioral therapy moderate activity in this area.

"Thus, successful placebo treatment works through the same mechanism in the brain," says Tomas Furmark at the Uppsala University Department of Psychology, who directed the study.

The study also analyzed two genes that influence the reabsorption and synthesis of serotonin in the brain (the serotonin transporter gene and the tryptophan hydroxylase-2 gene). The findings showed that only individuals who had certain variants, alleles, of these genes had a moderation of activity in the amygdala. Above all, the tryptophan hydroxylase-2 genes variants could predict the degree of relief from anxiety achieved by the placebo pill as well as the moderation of the amygdala.

Statistical analyses showed that it is a genetic effect on the activity in the amygdala that influences the propensity to respond to a placebo, that is, a path from the gene, via the brain, to behavior.

The study shows for the first time that genes influence the placebo effect by regulating the propensity to react in an area of the brain that is important for our feelings.

This could have significant consequences for all drug testing and other treatment studies that use a placebo.

"The findings show that the possibilities of demonstrating that an active treatment functions better than a placebo can be affected by the gene variants in the trial subjects. It is also possible that genes can explain why certain people respond well or poorly to anxiety-moderating drugs and psychotherapy respectively," says Tomas Furmark.

Source: Uppsala University

Explore further: Positive results from Alzheimer's drug in Phase 1 clinical trial extension

Related Stories

Positive results from Alzheimer's drug in Phase 1 clinical trial extension

November 3, 2017
The pharmaceutical company Biogen has today announced the results of an extended phase 1b clinical trial of the potential Alzheimer's disease drug, aducanumab. Results from the extended early stage trial, were announced today ...

Can Alzheimer's be stopped years before it starts?

September 15, 2017
Researchers at the Keck School of Medicine of USC are tackling the sixth-leading cause of death in the United States—Alzheimer's disease—with a new study that intervenes decades before the disease develops.

Study shows promise for children with severe form of epilepsy

October 2, 2017
A new formulation of a drug that was used to treat children with a rare neurological condition in the 1980s, and later became half of a widely used diet-drug combination, may offer promise for pediatric patients with a severe ...

Certain genes might make some people more prone to experience the placebo effect

April 13, 2015
Placebos have helped to ease symptoms of illness for centuries and have been a fundamental component of clinical research to test new drug therapies for more than 70 years. But why some people respond to placebos and others ...

Genetic marker for placebo response identified in IBS patients

October 23, 2012
Although placebos have played a critical role in medicine and clinical research for more than 70 years, it has been a mystery why these inactive treatments help to alleviate symptoms in some patients – and not others. Now ...

Gene silencing shows promise for treating two fatal neurological disorders

April 12, 2017
In two studies of mice, researchers showed that a drug, engineered to combat the gene that causes spinocerebellar ataxia type 2 (SCA2), might also be used to treat amyotrophic lateral sclerosis (ALS). Both studies were published ...

Recommended for you

A math concept from the engineering world points to a way of making massive transcriptome studies more efficient

November 17, 2017
To most people, data compression refers to shrinking existing data—say from a song or picture's raw digital recording—by removing some data, but not so much as to render it unrecognizable (think MP3 or JPEG files). Now, ...

US scientists try first gene editing in the body

November 15, 2017
Scientists for the first time have tried editing a gene inside the body in a bold attempt to permanently change a person's DNA to try to cure a disease.

Genetic mutation in extended Amish family in Indiana protects against aging and increases longevity (Update)

November 15, 2017
The first genetic mutation that appears to protect against multiple aspects of biological aging in humans has been discovered in an extended family of Old Order Amish living in the vicinity of Berne, Indiana, report Northwestern ...

Genetic variant prompts cells to store fat, fueling obesity

November 13, 2017
Obesity is often attributed to a simple equation: People are eating too much and exercising too little. But evidence is growing that at least some of the weight gain that plagues modern humans is predetermined. New research ...

Discovering a protein's role in gene expression

November 10, 2017
Northwestern Medicine scientists have discovered that a protein called BRWD2/PHIP binds to histone lysine 4 (H3K4) methylation—a key molecular event that influences gene expression—and demonstrated that it does so via ...

Twin study finds genetics affects where children look, shaping mental development

November 9, 2017
A new study co-led by Indiana University that tracked the eye movement of twins finds that genetics plays a strong role in how people attend to their environment.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.