According to a study conducted at the Icahn School of Medicine at Mount Sinai, specific combinations of gut bacteria produce substances that affect myelin content and cause social avoidance behaviors in mice. This research suggests that targeting intestinal bacteria, or their metabolites, could be one way to treat debilitating psychiatric disorders and demyelinating diseases, like multiple sclerosis.
Multiple sclerosis is an autoimmune disorder characterized by damage to myelin, the insulating sheath around the axons of nerve cells that allows for faster electrical impulse conduction. Myelination is critical for everyday brain function. Damaged myelin results in altered synaptic transmission and clinical symptoms. Previous research from the Center of Excellence for Myelin Repair at The Friedman Brain Institute at the Icahn School of Medicine reported a thinning of myelin and a reduction of myelinated fibers in preclinical models of depression, thereby providing a biological insight for the high rate of depression in MS patients.
Researchers transferred fecal bacteria from the gut of depressed mice to genetically distinct mice exhibiting non-depressed behavior. The study showed that the transfer of microbiota was sufficient to induce social withdrawal behaviors and change the expression of myelin genes and myelin content in the brains of the recipient mice.