The trillions of bacteria living in the human gut influence how our brain functions, our mood and behavior. Scientists have linked imbalances in this community of microbes to a range of psychiatric conditions, including depression, anxiety disorders, autism, schizophrenia, obsessive-compulsive disorder, social anxiety and neuroticism ... and the list goes on.
Now, medical researchers are turning their attention to finding ways to use the gut's microbiome to actually treat those illnesses.
New research from scientists with New York City's Icahn School of Medicine at Mount Sinai, published Wednesday in the journal eLife, suggests that altering the gut bacteria in a sick person might help alleviate psychiatric conditions, as well as certain diseases that attack myelin in the human body.
Myelin forms the protective layer around the axons of nerve cells that increases the speed at which the cell sends electrical impulses. When the myelin sheath is damaged, neural communication is impaired, resulting in neurological and behavioral markers of mental illness.
The study showed that when gut bacteria from depressed mice was transferred into healthy mice, there were changes to the myelin sheath in the brains of the healthy mice. And they began to engage in social avoidance behaviors characteristic of depression.
“There’s a symbiotic relationship between the two sides, human and bacteria."”
The researchers highlighted the potential of their findings in particular for the treatment of multiple sclerosis. MS is an autoimmune disorder characterized by myelin damage, and depression is common among its patients. Clinicians might be able to improve the functioning of the myelin layer and reduce those depressive symptoms by altering the patients' gut bacteria, the researchers noted.
"The study provides a proof of principle that gut metabolites have the ability to affect myelin content irrespective of the genetic makeup of mice," Dr. Patrizia Casaccia, a professor of neuroscience, genetics and genomics, and neurology at the medical school and the study's lead author, said in a statement. "We are hopeful these metabolites can be targeted for potential future therapies."
It's an exciting time for microbiome research. At MIT, scientists are hacking gut bacteria to create "synthetic biotics" -- microbes programmed to perform specific actions in the gut, like detecting inflammation and creating anti-inflammatory molecules. Like probiotics, these live bacteria could be taken in pill form.
"We're sort of like a walking vessel for these bacteria," Dr. Timothy Lu, a biological engineer at MIT who is spearheading the synthetic biotics research, recently told The Huffington Post. "There's a symbiotic relationship between the two sides, human and bacteria."
How exactly do microbes colonize and control the human body? Check out this "Talk Nerdy To Me" episode to find out: