#WSF18: Our Microbiome and the Brain

On Saturday at the World Science Festival, microbiologists David Relman, Jo Handelsman, Rob Knight, and Martin Blaser convened for a discussion on how the microbiome relates to our health. Our microbiome, the collective bacteria, viruses, fungi and other microorganisms that live in the digestive tract, allows us to digest food properly and fight off disease. Research suggests that an unhappy microbiome may contribute to autoimmune diseases, allergies, depression, and even Alzheimer’s.

According to Relman, our “built environment,” as well as modern hygiene, has altered our microbiome, and a deficient microbiome (sometimes caused by using antibiotics early in life and throughout the life span) has been associated with increased rates of asthma and obesity. While this does not prove causality, said Relman, it suggests that the microbiome plays some role in a number of diseases.

Handelsman believes one such disease is depression. She described a mouse study where healthy mice who received transplanted fecal matter from depressed humans began to exhibit depressive symptoms, such as acting withdrawn and demonstrating little motivation for survival (they gave up swimming to safety when placed in water).

There is a real and palpable connection between the brain and the gut, stated Handelsman, and it’s been known for a long time. But only recently have we begun to investigate the implications, she said. For example, gut bacteria produces an estimated 90 percent of the neurotransmitter serotonin, which is important for regulating mood.

Blaser spoke about inheriting our microbiome; the genes of the microbes are potentially passed on, transmitting conditions such as irritable bowel syndrome. He also noted that if a mother has an unhealthy microbiome, it has been shown to lead to susceptibility to premature birth and other conditions.

Stay tuned for more coverage from the World Science Festival, exploring such topics as extremism, artificial intelligence, and music and the brain. Also, be sure to check out two of our recent articles on heritability of mental health and the possible connection between the gut and number of brain disorders such as Parkinson’s disease and depression.