the patient's intestines may not be the most obvious place to look for the origins of depression. But it was the assumption of the British chemist George Porter Phillips in the early 20th century.
As I walked through the wards of the notorious scandal in London, Phillips noted that their patients with melancholia often suffered from severe constipation, along with other signs of "total blockage of the metabolic processes" – including brittle nails, hair and unglazed yellowish complexion.
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Initially, one might think that these physical problems were caused by the depression, but if the opposite were true? Phillips asks if he can relieve depression bowel treatment.
To prove this hypothesis, he fed a patient with a low-calorie diet without meat, except fish. Also offered them sour milk drink called kefir, containing Lactobacillus bacteria, microbe, "friendly", which was already known to aid digestion.
Surprisingly, it worked. From the 18 patients tested for Phillips, 11 were cured completely. The other two showed significant improvement.
Was no evidence that our gut bacteria can have a profound impact on our mental condition.
Power intestinal flora when considering
BBC Future series examined some statements about the strength of our intestinal flora to cause healing or damage. But the relationship between these microorganisms and our mental health with the & # 39 is probably the most impressive. our brains may be affected in these microscopic creatures that feed on the remains of our digestion?
Some of these results were overstated. But more than a century after the original experiment Phillips, the relationship between the gut brain is quite hard.
"The influence of microbes in our mental health is not being discussed," says Jane Allyson Foster, whose lab at McMaster University in Canada, is engaged in research in this area. This means that we can cure the brain through our stomach. "There is a potential for the development of new treatments, both with precision medicine."
Foster notes that the unhealthy intestine is only one of many possible causes of mental illness. In other words, only part of the patients will respond well to new treatments «psicobióticos». But for those who suffer from an imbalance in their gut bacteria, new treatments can bring much-needed relief.
Although the first study, including Phillips, the idea that the intestine can affect our mental health disgraced throughout most of the 20th century, and convincing evidence of this mysterious connection again with the & # 39 appeared only in the last two decades.
One of the highlights of modern experiments have been made by scientists at the University of Kyushu, Japan, in 2004.
They showed that mice "without microorganisms" – created in a sterile environment, so that they did not have germs in their bodies – have shown significant variations of corticosterone and ACTH hormone, is known to reflect the level of stress. This demonstrates that the intestinal bacteria of healthy mice, one way or another, creating a hormonal profile.
Then the researchers gave a group of mice not rudiments of lactobacilli – class "friendly" bacteria that Phillips also took advantage of the melancholic patients. Although these mice still presented a higher stress response than mice that had not been released by microbes, their reactions to stress were less pronounced than mice without any microbe in the gut.
There are even some indications that the depressive behaviors can be passed by types – from man to mouse – because of the microbes in the gut.
In another study, Chinese researchers from Chongqing collected samples of intestinal flora in patients with major depressive disorder and mice entered the bud.
Later, they found that these mice were given faster while swimming "forced" exercise – behavior that is often considered similar to lethargy and depression, the typical symptoms of depression. And if the mice were placed in a box, less time spent exploring the central areas and are closer to the edge, where they felt safer.
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"What is surprising is that the animals that received the intestinal flora" depressive "acted as" depressive "," says Julio Lisin, New York Upstate Medical University, who co-authored the article. "If you change the intestinal flora, to change the behavior. "
We can draw some conclusions from these animal studies, of course – but they are supported by epidemiological studies that analyze the large number of human participants (the last was published February 4, 2019). These studies have shown consistently that the changes in the intestinal flora of the same variety of mental illnesses, including depression and anxiety.
No single species does not seem to be responsible for these effects; Much more important would be the total share of the different families of microbes. Thus, the intestinal flora of depressive and anxious people show less varied than that of people with mental health without any problems.
Surprisingly, one of the last works of Licínio shown that schizophrenia is associated with impoverished intestinal flora. If patient samples suffering from the disorder have been implanted in uninfected mice researcher was able to confirm characteristic changes in brain activity, with & # 39 are the hallmark of the disorder.
These effects can occur in many ways.
Certain types of intestinal bacteria may protect the intestinal wall, helping to keep its mucous membrane, which prevents the contents from spilling into the blood. Without this bar & # 39; EPA, you may suffer from the syndrome of "porous intestine", which is, among other things, the release of pro-inflammatory cytokines, proteins that increase the flow of blood around the foci of infection and regulate the body's immune response.
Although this reaction is crucial for fighting infection, these cytokines can also lead to moodiness and lethargy. That is why we often feel tired, when we are sick – and short-term, this response is helping us to save energy that our body needs to find an infection. But the long term can lead to depression.
Gut microbes also affect both digest and absorb the key precursors of neurotransmitters, such as serotonin and dopamine. Our gut flora even has a direct line of communication with the brain via the vagus nerve (or pneumogástrico), which is near the receptors of the intestinal mucosa, which allow you to control our digestion. Microbes in the intestine can thus produce chemical mediators that alter the response of the vagus nerve – and hence the activity of the brain.
"In particular, in the gut, there are many opportunities for the bacteria to communicate with host systems, including the nervous system," says Foster. "This is a very dynamic and interactive space and rich."
But this is not a one-way street. Thus, brain activity can also influence the composition of the intestinal flora. Stress can, by itself, increases inflammation, for example, that could affect the microbes in our intestines. The result is a vicious circle.
Foster says that research in this area is rapidly accelerated by scientists associated with universities and companies.
Ultimately, the researchers hope that their findings will lead to a new type of treatment of diseases, such as depression.
Currently existing antidepressants work by altering the balance of chemicals, such as serotonin in the brain, but are not effective in all patients: only two out of ten taking antidepressants show signs of improvement for the placebo effect. And while helping many patients, speech therapy, such as cognitive-behavioral therapy is equally unpredictable. As a result, many patients are not treated or struggle to find an appropriate treatment.
Some efforts – as the study Phillips in 1910 – fed patients with fermented beverages such as yogurt, which can enter the gut bacteria and proteins that are known to be useful for digestion, or soluble fibers known as "prebiotics," which helped to reiterate our intestinal flora. Unfortunately, many of these studies are generally small, with a small number of participants, and the results were ambivalent: in some studies, the intervention reduced the success of the symptoms; in other studies, there was no better than placebo.
One explanation, according to Foster, with & # 39 is that the failed studies have focused on patients who will benefit more from this type of treatment. In the end, there are many causes of depression, and although the problem of the intestinal flora may be the main cause of depression or anxiety in some people, in particular, the trigger can be quite different. For them, it is unlikely that a probiotic drink to make a big difference in your symptoms.
To further complicate the microbiome of each of us is unique – so any treatment that affects these differences should be considered in the intestinal flora. In general, when comparing inter & # 39; bowel career two individuals, the degree of similarity is only 10%.
For this reason, she thinks we need to find more sophisticated ways to adapt the patient's treatment. "That's where the brain gut help us exactly medicine." Hope, Foster says, is the "map" biotypes "or a group of people who share specific biology, which could be decisive in their symptoms." Therefore, it would be appropriate to check, have high or low patient inflammation before deciding on the most appropriate treatment for him.
Licínio also remains cautiously optimistic that future research will identify treatments aimed at the axis of brain cancer. He says that the significant side effects of antidepressants have limited the development of new pharmaceutical treatments – but this approach can avoid these problems. "You do not tampering with the brain," he says, "so I think any side effect that you will have to be less problematic."
Although we still need to improve our knowledge about the relationship between our gut and our brain that we know today points to the growing evidence that a healthy, balanced diet can be an important preventive measure to reduce the risk of diseases such as depression,
Many of these studies examined the "Mediterranean diet" – a term used to describe a diet rich in vegetables, fruits, nuts, seafood, unsaturated fats and oils, as well as low in refined sugars and red and processed meats.
A study in Spain found that people who followed a traditional Mediterranean diet were about twice as likely to be diagnosed with depression for four years.
"Data on the importance of nutrition for mental and brain health is now widely and very consistent," said Felice Jacka, nutritious psychiatrist from Deakin University in Australia, and author of Brain Changer: Diet Good Mental Health (transforming your brain: a good diet Mental Health, in a free translation).
Studies show that the Mediterranean diet has increased the diversity of gut bacteria and reduce other physiological changes, such as chronic inflammation, which also seems to be accompanied by depression.
More than a hundred years after the experience of Phillips, depression is still no cure, but for some people, at least, a healthy gut is an important first step on the way to a happy mind.
- reading original version This report (in English) on the website BBC Future.
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