The Connection Between Emotions and Physical Health: The Mystery of the Placebo Effect Unraveled

Scientific evidence that “poor mood can really cause digestive, skin inflammation, cardiovascular health problems”, but why?

You must have heard of the placebo effect, but why exactly? This mystery has baffled scientists for several generations, and it has remained unsolved for more than a hundred years. Until recently, a part of the mystery has finally been revealed.

The biomedical circle is very excited, thinking that once the secret is cracked, we will know why stress makes people sick! Even better, there’s the chance to create new treatments for diseases and cancers that afflict countless people! ? Is it possible to cure diseases by “changing thoughts”?

The placebo effect refers to the fact that even if the patient takes or injects a non-real drug, the resistance to foreign pathogens or internal lesions will improve and the body will improve. For a long time, scientists were ignorant of the mechanism behind this phenomenon.

There are two questions that are directly related to solving the mystery of the placebo effect. At first glance, they are very inconspicuous questions, but if you think about it for a second or three seconds, you will find that you can’t answer them.

Colds, irritable bowel syndrome, and placebos all have the same answer

You must have had this experience: after catching a cold, you have no appetite, can’t lift your spirits, and just want to lie flat on the sofa. Why is this happening? Isn’t it because pathogens invade the body that we “feel” uncomfortable? But when you think about it again, the bacteria or virus didn’t directly attack the brain at all, so why do you have these nasty feelings?

Furthermore, many people are prone to diarrhea, stomach pain, and flatulence when they are nervous, and some people, on the contrary, become constipated when they are nervous. These are common symptoms of irritable bowel syndrome (irritable bowel syndrome, referred to as irritable bowel syndrome). But why do emotions that take place in the brain directly stimulate the bowels far away in the abdominal cavity?

In response to the first question, a study in “Nature” in June 2022 found that as long as a specific area of ​​​​the hypothalamus of the brain is stimulated, mice will have fever and loss of appetite even if there are no germs in the body. In other words, infection will trigger immune cells to attack pathogens, leading to inflammation in the body. The brain does not need to touch pathogens, as long as it senses the inflammatory stimulus through blood and other channels, uncomfortable symptoms will appear.

As for the second, a study published in the journal “Cell” in November 2021 pointed out that if the intestines of mice were once inflamed, stimulating the insular cortex (insular cortex) can recreate the inflamed state; that is, the brain will retain The memory of the immune system’s activity can restart the same immune response in the gut as long as the same group of nerve cells is activated in the future.

A review article in “Nature” at the end of February 2023 stated that scientists suspect that this neural mechanism is the body’s preparation in advance to resist possible threats, but it will also be clever and misunderstood by cleverness, and it will automatically activate when there is no original trigger. Triggers, such as stress making symptoms of irritable bowel disorder worse, might be in this category.

What clues do these findings reveal?

The severity of the illness and how quickly it recovers are controlled by the brain

The placebo effect and the previous two questions all point in one direction, the one that keeps appearing in the three phenomena-the immune system.

Scientists have found that all the current evidence points to the fact that the brain, and the nerves that run throughout the body, are actually tied to the immune system in a way that is not well understood.

It can also be put another way: how emotions, positive and negative emotions are connected with the body, at least one path has been found to be through the close interaction between the nervous system and immune cells.

At the end of May 2022, “Nature” published a report, introducing the research team of Harvard Medical School in the United States using “optogenetics” and other technologies to draw a map of how white blood cells in the mouse brain and body “interact”. This gives us the opportunity to further speculate about what is going on in the human body.

The so-called optogenetics can simply be imagined as implanting a designed protein gene into the neuron cells you want to observe. Once this protein is irradiated with light of a specific wavelength, it will activate and stimulate the activation of nerve cells, so that you can Only a single type of nerve cell is operated very finely at a time, and a brain map with a relatively high resolution is drawn.

The team was surprised to find that the brain directs the immune system in two ways. One is that the brain’s motor circuits that control body movements send signals to stimulate skeletal muscles to release cytokines that attract immune cells called neutrophils. , inducing the rapid movement of neutrophils originally in the bone marrow to the site of infection or injury. The other is that the paraventricular hypothalamus in the brain will secrete specific chemical molecules, command the adrenal gland to secrete hormones, and quickly guide monocytes and lymphocytes to move from lymph nodes, spleen, blood vessels, etc. to the bone marrow.

Coincidentally, at the end of April 2022, a multinational team of German and other European scientists also published research results in “Nature”, directly showing that the process of atherosclerosis may be partly controlled by the brain; How are the three systems of immune system, immune system and blood circulation integrated?

Atherosclerosis is the accumulation of cholesterol in the blood on the inside of the blood vessels, forming plaques. There will be chronic inflammation in local areas, and the blood vessels will become narrower and narrower. Once the plaque flakes off, it becomes a blood clot, which is a key factor in strokes, angina pectoris and myocardial infarction. There is currently no medical technology that can reverse the hardening of the arteries in patients.

The research team found that the nerve fibers in the outer layer of the arterial wall of the mouse can transmit signals to the brain and also receive the signals from the brain. Immune cells will gather in large numbers around the nerve endings, and a similar phenomenon occurs in the human body. They experimented with mice, using chemical methods or surgery to cut off the nerve connection, and the immune cells were quickly disbanded on the spot, and the accumulation of vascular plaques also slowed down.

know how to ask the brain for help

The brain can direct the body to resist illness, which reasonably explains the personal pain that you and I have probably experienced, that is, when the mind is full of negative emotions such as stress and anxiety, it is particularly easy to get sick, such as colds, gastroenteritis, Itchy skin etc.

What’s more interesting is, conversely, if you create positive emotions, is it also useful for resisting diseases? The answer may also be yes.

It has been reported in the past that breast cancer patients who join support groups and receive some psychotherapy can prolong their survival, and a similar phenomenon has been suggested in studies of several other cancers such as lung cancer, malignant melanoma, and gastrointestinal cancers.

Therefore, many research teams around the world are now studying how to make good use of the power of “body” and “mind” and combine them to cure diseases.

For example, cancer tumors will release nerve signals and secrete chemical substances, which will cause the patient’s metabolic mechanism and sleep disorder. And sleep cycle “joe” back, helps to help cancer patients feel comfortable during the recovery process.

The Technion-Israel Institute of Technology team focused on the ventral tegmental area (VTA), located in the midbrain. VTA is the reward center of the brain. It contains cells that secrete dopamine, which is related to emotions such as expectations, motivation, and preferences. It is the brain area that makes us feel happy and excited to take practical actions. The team found that stimulating the VTA can drive the immune system to shrink tumors in the lungs and skin of mice, and they now want to transfer the results from mice to humans.

There is also a team that starts from the vagus nerve. The vagus nerve is a major member of the parasympathetic nervous system. It runs from the brain all the way down through the heart, lungs, stomach, and extends to the large intestine. It is known to be involved in regulating immune responses. A start-up company, SetPoint Medical, has used their technology to develop a capsule-sized nerve stimulation device that is implanted next to the vagus nerve in the neck. It can be charged wirelessly and the stimulation intensity can be adjusted with an iPad program. The goal is to treat rheumatoid joints Inflammation, Crohn’s disease (Crohn’s disease) and other autoimmune diseases.

“Integration of mind and body”, in more perceptual terms, means that when the mind suffers, the body also suffers. It turns out that this incident is not just a subjective personal feeling, but actually has a physiological truth.

Perhaps, more importantly, let people who feel uncomfortable but have been unable to find out the cause know that their feelings are not moaning for nothing, nor are they trying to escape pressure or do something wrong, but that the body and mind are really sending out an alarm. Maybe This is the greatest consolation.

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