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Gut Microbiome-Mood Link?

There is increasing evidence that gut bacteria can affect the brain and, potentially, mood, the New York Times Magazine reports.

Mark Lyte, now at Iowa State's College of Veterinary Medicine, has been studying this gut-brain link for decades, finding that stress in animals affects their microbes and that animals with and without certain microbes exhibit different behaviors. For instance, the Times' Peter Andrey Smith writes that Lyte gave mice Campylobacter jejuni, which can make people ill, but not mice, and while the mice seemed healthy, those given the bacteria were less likely to walk on the high ledges of a lab maze than mice that didn't ingest the bacteria. These mice given C. jejuni, he noted, seemed anxious.

Other researchers, Smith reports are also beginning to investigate this link, and the US National Institute of Mental Health awarded four $1 million grants to study whether the gut microbiome plays a role in mental disorders. This funding, he adds, "affirm[ed] the legitimacy of a field that had long struggled to attract serious scientific credibility."

According to Smith, Lyte is now cataloging psychoactive compounds like dopamine, serotonin, and gamma-aminobutyric acid that are found in monkey feces, and he plans to then transfer the gut microbiome from one monkey to another to gauge how that change influences the monkey's neurodevelopment.

"Anxiety, depression and several pediatric disorders, including autism and hyperactivity, have been linked with gastrointestinal abnormalities," Smith adds. "Microbial transplants were not invasive brain surgery, and that was the point: Changing a patient's bacteria might be difficult but it still seemed more straightforward than altering his genes."