Discovery of gene variants that impact the placebo effect
Two new studies led by researchers at the University of California, Berkeley, suggest that taking maternity leave before and after the birth of a baby is a good investment in terms of health benefits for both mothers and newborns. One study found that women who started their leave in the last month of pregnancy were
Full Post: Maternity leave appears to decrease cesarean deliveries and increase breastfeeding
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.
A network of emotion-regulating brain regions implicated in the pathological worry that can grip patients with anxiety disorders may also be useful for predicting the benefits of treatment. A new study appearing online Jan. 2 reports that high levels of brain activity in an emotional center called the amygdala reflect patients’ hypersensitivity to anticipation of
Full Post: Expectant brains help predict anxiety treatment success
A collaborative study led by investigators from Massachusetts General Hospital (MGH) is giving what may be the first look at how interactions between genes underlie a key symptom of schizophrenia, impaired working memory. Functional imaging studies reveal how a combination of common variants in two genes is associated with reduced activity of important brain structures
Full Post: Interaction between gene variants may alter brain function in schizophrenia
Many older adults worry - a lot. Almost one in 10 Americans over age 60 suffer from an anxiety disorder that causes them to worry excessively about normal things - like health, finances, disability and family. Although antidepressant drugs known as selective serotonin reuptake inhibitors (SSRIs) can improve anxiety symptoms in younger adults, little
Full Post: Anxious seniors may benefit from SSRIs
An international research team has identified 11 novel locations in the human genome where common variations appear to influence cholesterol or triglyceride levels, bringing the total number of lipid-associated genes to 30. While major mutations in some of these genes have been known to underlie rare lipid metabolism disorders, it is becoming apparent that common
Full Post: Discovery of 11 new gene sites that influence cholesterol or triglyceride levels
Rewarding and stressful signals don’t seem to have much in common. But researchers studying diseases ranging from drug addiction to anxiety disorders are finding that the brain’s reward and stress signaling circuits are intertwined in complex ways. Vanderbilt University Medical Center investigators have now discovered a functional link between reward and stress. They found that
Full Post: Researchers find brain’s reward and stress signaling circuits are intertwined in complex ways