Depreciation? Bacteria in your gut may have caused – or made you healthier

In a series of studies, researchers are finding that the microbial menagerie that resides in our digestive tract may help regulate brain function, including mental health. . Recent findings by scientists in the US, Europe and China link our feelings of stress, anxiety and depression to disturbances among hundreds of microbe species living in our gut that some of researchers have begun calling the psychobiome.

On the other hand, other bacteria in the gut seem to produce some of the same substances that doctors use to treat depression and may play a part in it. maintaining our emotional balance.

“Feeling of malaise, if you will, is often associated with gastrointestinal disorders,” said microbiologist Jack Gilbert of the University of California, San Diego and the Scripps Institute of Marine Science, who helped study microscopy -fly human gut. It is “chemically altering zero signals that enter the brain, which alters brain chemistry and therefore behavior, emotion and, we believe, depression and anxiety.”

As evidence, some scientists have been able to capture mice and rats with mental disorders, including depression and anxiety, by translating stool samples, which contain gut microbes. , from human patients to laboratory animals, several recent studies show. “When you give these mice the microbes of depression, they will start behaving in a depressed manner,” said psychiatrist Julio Licinio at New York State University School of Medicine in Syracuse. These behavioral changes in mice affect things such as desire, weight lifting and activities such as swimming. Dr. Licinio studies the biology of depression and helped design some of the experiments. “It simply came to our notice then,” he said.

Until now, however, it has not been possible to associate certain species of microbes with mental illness. This month, an international research team identified for the first time dozens of species of gut microbes involved in depression by comparing patients diagnosed with the disorder to humans. healthy. These 47 species are a small fraction of the microbial diversity of the gut, which includes other single-celled organisms, thousands of species of viruses and fungi.

The new research by neuroscientist Peng Xie at the First Associated Hospital at Chongqing Medical University in China and colleagues reveals a potential tool for mental illness that affects around 350 million people worldwide, several experts said. The research was published in the journal Science Advances.

Scientists are in a hurry to find out how such microbes interact with the human central nervous system, what signals they send to the brain and how that changes a person’s behavior or danger from mental illness, the prospect of new treatments and a diet for depression.

“The big race is about realizing how they play a role in a number of brain diseases,” said Emeran Mayer, a medical psychologist at the University of California, Los Angeles who studies brain and gut and who has written “The Mind-Gut Connection. ”He said,“ if you already have genetic risk factors for Parkinson’s or Alzheimer’s disease or depression, this is a trait that can push you over the edge to disease. ”

Not so long ago, germs that caused diseases and infections were the only microbes that attracted medical attention.

But improper use of antibiotics and other hygiene measures have eliminated the damage caused by bacteria at the expense of the protection they can provide. Abnormal health outcomes ranged from increases in liver disease, Type 2 diabetes and asthma to premature birth and antibiotic-related diarrhea, according to a 2019 study in the Journal of Experimental Medicine and many other microbiological studies.

In the last decade, advances in fast-cost low-speed gene mutation machines have allowed researchers to study millions of microorganisms that are not normally grown in a laboratory. In these studies, researchers can find out if genetic material is related to bacteria even though there is a biomarker called the 16s ribosomal RNA gene, which converts only into microbes.

As a result, the study of the microbiome is one of the hottest new areas in medicine, with more than 15,000 scientific papers published last year alone. “There’s a lot of excitement in the field of psychology now about this,” said John Cryan at University College Cork in Ireland, who studies midges and stress neurobiology.

Microbes estimate that there are over 100 trillion microorganisms in the human gut. Together they weigh about 5 pounds – about the size of a giant mango and a little more than the human brain, according to the European Society of Neurogastroenterology and Motility.

In addition, where the human genome carries about 22,000 protein-coding genes, researchers estimate that the human midge encodes approximately eight million specific protein-coding genes , or 360 times more bacterial genes than human genes, according to the National Institute of Health’s Human Microbiome Project. .

These microbes are particularly susceptible to changes in the environment, diet and emotional biochemistry. Although it is not yet known why, patients with various psychiatric disorders including depression, bipolar disorder, schizophrenia and autism spectrum disorder have major complications in the composition of the their gut flies.

The microbes appear to be in almost constant contact with the brain directly by affecting zero signals and indirectly through chemicals introduced into the bloodstream, the said Dr. Gilbert, who is also a scientific advisor for a small microbiome company called Holobiome in Cambridge, Mass., Is looking for new ways to treat depression, insomnia and other ailments.

Some common gut bacteria, for example, help generate neurotransmitters such as serotonin, which affect mood and memory-related neural activity. It is commonly used to treat depression. Others make an amino acid called gamma-aminobutyric acid that naturally blocks some brain signals. It is used in medicine to relieve anxiety and to improve mood.

“The bacteria overwhelm parts of systems within the body that we know affect emotional regulation,” said Dr. Cryan. “This has led us to believe that by targeting microbes in the gut, we can have behavioral effects that affect overall well-being.”

Write to Robert Lee Hotz at [email protected]