The brain and the microbiome

Hutch: Dr. Meredith Hullar is a microbial ecologist at Fred Hutch who got her start at Harvard studying the complex metabolism of microorganisms in the sea. She collaborates closely with Lampe on dietary research and the role of microbial metabolism in human health. Hullar is a fan of large studies that bring together huge amounts of disparate data, searching for patterns. One such project she and Lampe are involved in is the Multi-Ethnic Cohort study, which is comparing the microbiome profiles of 6,000 men and women from five different ethnic groups in Hawaii and California. It's a massive undertaking, sequencing microbial genes from 7,200 stool samples and matching data from questionnaires, medical exams and whole-genome screens that can spot gene variants in each participant. The goal is to link the makeup and function of the gut microbiome to risks of obesity and cancer.

But the study is also exploring the connection between gut bugs, the brain and behavior. While signals from the gut to the brain help determine whether a person "feels full" after a meal, certain gut bacteria may alter that communication, influencing behavior linked to weight gain. "Understanding how the gut microbiome influences the brain's regulation of body fat may add to our understanding of how to prevent and control obesity, which is linked to increased risk of certain cancers," said Hullar.
To probe this gut-brain link, brain-imaging scans, including MRIs, are being offered to 100 women participants in Hawaii, who also fill out standardized behavioral surveys. These scans will add data on brain chemistry and structure to the other health information already gathered. It is a breathtaking illustration of how sophisticated microbiome research has become. A project that began with stool samples now has high-speed computers crunching big data from genomic screens, proton spectrographs and MRI readouts.