08 January 2015 - Science Daily - Could gut microbes help treat brain disorders? Mounting research tightens their connection with the brain

Over the past 10 years, studies have linked the gut microbiome to a range of complex behaviors, such as mood and emotion, and appetite and satiety. Not only does the gut microbiome appear to help maintain brain function but it may also influence the risk of psychiatric and neurological disorders, including anxiety, depression and autism.

Three researchers at the forefront of this emerging field recently discussed the microbiome-brain connection with The Kavli Foundation.

"The big question right now is how the microbiome exerts its effects on the brain," said Christopher Lowry, Associate Professor of Integrative Physiology at the University of Colorado, Boulder. Lowry is studying whether beneficial microbes can be used to treat or prevent stress-related psychiatric conditions, including anxiety and depression.

One surprising way in which the microbiome influences the brain is during development. Tracy Bale, Professor of Neuroscience at the School of Veterinary Medicine at the University of Pennsylvania, and her team have found that the microbiome in mice is sensitive to stress and that stress-induced changes to a mother's microbiome are passed on to her baby and alter the way her baby's brain develops.

Sarkis Mazmanian, Louis & Nelly Soux Professor of Microbiology at the California Institute of Technology, is exploring the link between gut bacteria, gastrointestinal disease and autism, a neurodevelopmental disorder. He has discovered that the gut microbiome communicates with the brain via molecules that are produced by gut bacteria and then enter the bloodstream. These metabolites are powerful enough to change the behavior of mice.
Mazmanian's lab is also exploring whether the microbiome plays a role in neurodegenerative diseases such as Alzheimer's and Parkinson's.

The work of these three researchers raises the possibility that brain disorders, including anxiety, depression and autism, may be treated through the gut, which is a much easier target for drug delivery than the brain. But there is still much more research to be done to understand the gut-microbiome-brain connection, they said.