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The placebo effect depends on genetics
Last reviewed: 01.07.2025
Scientists from Harvard Medical School and the Beth Israel Deaconess Center have concluded that the placebo effect works on people who have a certain genetic sequence.
Experts studied the placebo effect in people with different variants of the COMT gene, which codes for the protein cotechol-O-methyltransferase, which is involved in the catabolism of dopamine, a neurotransmitter responsible for feelings of pleasure.
The study involved 104 people who suffered from irritable bowel syndrome, which causes chronic abdominal pain, discomfort and bloating. All subjects were divided into three groups, and the selection was random.
Two groups of participants received placebo acupuncture treatment (needles did not enter the skin), and a third group received no treatment at all.
The volunteers from the first group underwent therapy in a normal environment, while the doctors maintained friendly, warm relationships with the participants of the second group. A month after the start of the study, the participants were asked to describe their condition and well-being. Blood samples from all volunteers were also taken for analysis.
Scientists have found that those people who were carriers of two alleles of the COMT gene with methionine at position 158, felt a significant improvement in their condition, which means they were most susceptible to placebo. Those participants who had methionine replaced with valine in one of the alleles also had improvements, but not as pronounced. No changes were found in patients who were carriers of two alleles with valine at position 158.
As the scientists assumed, the success of the placebo effect also depended on the trusting relationship between the doctor and the patient. The volunteers from the second group showed the highest result, because they had good relationships with the doctors, they were cared for and supported, which influenced the final result.
However, despite the success of the research, experts say that further studies of the placebo effect and genetic predisposition are needed. In the near future, experts plan to conduct similar experiments on patients with other types of diseases.