In mice with active inflammation, suppressing the neurons that remembered it produced an immediate reduction in the inflammation.
Your phone pings. It’s a message from a friend you met for drinks last night, who just tested positive for Covid-19.
Your throat starts feeling scratchy. A short cough sputters out. Is your body temperature rising? You run to take a PCR test. When the results come back negative, you realize it was all in your head — a psychosomatic response.
Researchers from the Technion – Israel Institute of Technology in Haifa wanted to explore the connection between the brain’s perception of illness and the real thing.
They induced inflammation in mice, and after the inflammation subsided, the researchers triggered the neurons in the mice’s brains that were active during the initial inflammation.
The result was dramatic: The inflammation re-emerged in the same area as before. Simply “remembering” the inflammation was enough to reactivate it.
The researchers then wondered: If the brain can generate disease, can the brain also turn it off?
The answer was a resounding yes. In mice with active inflammation, suppressing the neurons that remembered it produced an immediate reduction in the inflammation.
There’s no guarantee this experiment would work in human beings. But it raises the possibility of a new therapeutic avenue for treating chronic inflammatory conditions such as Crohn’s disease and psoriasis.
The brain’s ability to bring on illness psychosomatically is more a feature than a bug, explained Prof. Asya Rolls, of the Technion’s Faculty of Medicine.
“The body needs to respond to infection as quickly as possible before the attacking bacteria or viruses can multiply,” she said.
“If certain activity – for example consuming particular foods – has exposed the body to infection and inflammation once, there is an advantage to gearing up for battle when one is about to engage in the same activity again. A shorter response time would allow the body to defeat the infection faster and with less effort.”
The research was led by Tamar Koren, an MD-PhD student in Rolls’ lab. Other participants included Dr. Kobi Rosenblum of the University of Haifa and Dr. Fahed Hakim of EMMS Hospital in Nazareth.
The study was supported by the European Research Council (ERC) Starting Grant, the Allen and Jewel Prince Center for Neurodegenerative Disorders of the Brain, the Howard Hughes Medical Institute (HHMI) and the Wellcome Trust.
Can our brain make our body sick? Likely yes, Israeli research shows
Technion scientists uncovered how neurons can trigger physiological responses in the body that translate in real illnesses but might also help treat them.
Can our brain trigger an actual illness in the body? New research by Technion-Israel Institute of Technology scientists conducted on mice suggests that the answer is likely yes.
Over the years, the intuitive idea that the brain exercises a significant influence on people’s physical well-being has been supported by increasing scientific evidence.
“Several years ago, we studied the mechanism behind the placebo effect, demonstrating that when people experience a positive expectation, their conditions improve in many ways,” Technion Prof. Asya Rolls said.
“We were able to show that by activating brain areas that are related to positive expectations, we would boost the immune response,” she said. “What amazed us was how precise this response was, and therefore we thought that the brain could not have such an exact control of the system without knowing what its status is.”
The researchers started to examine whether the brain is able to represent the status of the immune system.
The new study was led by Rolls and her MD/PhD student Tamar Koren and was conducted in cooperation with Dr. Kobi Rosenblum of the University of Haifa and Dr. Fahed Hakim of EMMS Nazareth Hospital. The results were published in the journal Cell on Monday.
The scientists checked which areas of the brain would be activated when mice experienced genetically induced colon inflammation. Among others, the insular cortex – which is responsible for sensations such as thirst, hunger and pain and other manifestations of the body’s physiological state – presented increased neurological activity.
“When we reactivated the same neurons afterward, we recorded the same inflammatory response,” Rolls said. “It was quite shocking.”
The results offer evidence that the brain contains a representation of the immune system, and it can reactivate it when presented with specific stimuli and possibly other forms of memories, the researchers said.
The brain does not cause the body to be reinfected by a pathogen, but it might potentially trigger a reaction in the body similar to the one caused by the original infection, they said.
“We have to remember that, many times, the damage to the body is not caused by the pathogen itself but, rather, by the immune system’s reaction to it,” Rolls said.
The mechanism may help explain what triggers psychosomatic disorders, which are health problems that appear without any apparent biological cause, the researchers found. Autoimmune diseases or other conditions, such as Crohn’s disease, could also be based on a similar process.
It would be wrong to assume that the results obtained from the study on mice will translate in humans in the exact same way, Rolls said.
However, there is hope that the research can contribute to understanding better how certain diseases work and how to treat them, possibly by inhibiting the neurons from activating and triggering the inflammation.
“There are many ways we can control neuronal activities in the human brain, for example, through magnetic or electrical stimulation or by neurofeedback when a person learns how to control their neurons on their own,” Rolls said.
“We know that we can do it because we know the power of a psychosomatic effect,” she said. “For example, during the clinical trial of the COVID vaccine, many people who received the placebo experienced very similar side effects to those who received the actual vaccine. Clearly, this was caused by some mental process resulting in a physiological response.”