The Gut-Brain Axis: How Our Digestive System Affects Our Mental State


A new study adds evidence to the growing theory that the microbes in our guts are somehow linked to the state of our brains. This field of research could someday lead to targeted treatments for disorders like depression or dementia.

Professors Levi Waldron and Heidi Jones of the Graduate School of Public Health and Health Policy authored the study, with CUNY SPH alumni Audrey Renson and Lora Kasselman. The study was published in Brain, Behavior & Immunity.

More and more research has pointed to the existence of a “gut-brain axis”—the idea that the microbial flora in the digestive system have an impact on a person’s mental state, behavior, and even memory. However, much of the work done so far has been on animals, and the research that uses human volunteers tends to be about younger people. To the authors’ knowledge, this new study is the first randomly selected population-based cohort study on the subject that looks at multiple psycho-cognitive traits in older adults.

The researchers used data and participants from the Wisconsin Longitudinal Study. They assessed volunteers’ cognitive function, mood, and personality traits, and analyzed fecal samples to see what microbes were living in people’s guts.

The results showed that many different microbial groups had connections to mental traits. For instance, bacteria in the Butyrivibrio genus were associated with cognition, while Cloacibacillus bacteria were associated with mood, and Fusobacteriumwas associated with both personality and cognition. The researchers also found associations with more specific characteristics—Butyrivibrio bacteria had a negative association with verbal fluency, for example.

These results are preliminary, the authors write, so it is still too early to make generalizations about these connections. That said, the work supports the idea of a gut-brain connection, and with more research, this knowledge could help us understand and address issues around mental health.

Beyond SUM

Work By

Levi Waldron (Associate Professor, Epidemiology and Biostatistics) | Profile 1
Heidi Jones (Associate Professor, Epidemiology and Biostatistics) | Profile 1