Chemo Brain Isn’t All In Your Head, Your Gut Plays a Role

Chemotherapy disrupts the gut microbiome — the ecosystem made up of trillions of microscopic organisms in your intestines. A new study suggests the way chemo affects the gut may help explain why some people with breast cancer experience cognitive decline, or chemo brain, during and after treatment. The results were published in the journal Brain, Behavior, and Immunity.

Chemo brain affects up to 75% of women receiving chemotherapy for breast cancer. Researchers aren’t sure why some people have more problems with chemo brain than others, but understanding these differences could lead to new ways to treat these symptoms.

“The potential connection between the gut and the brain would allow us to create treatments for the gut to treat the brain,” senior author Leah Pyter, associate professor of psychiatry and neuroscience at Ohio State University, said in a statement.

Recent studies have offered tantalizing glimpses into how the microbes in your gut talk to your brain (through the immune and nervous systems). Earlier research in mice found that chemotherapy-induced changes in the gut microbiome led to changes in how the brain works and behavioral side effects. Could the same be true in people treated with chemo?

The researchers collected blood and fecal samples from 77 women diagnosed with breast cancer before, during, and after chemotherapy. They also gave the women cognitive tests to assess their thinking and memory skills and asked the women to evaluate their own cognition.

“We found that patients treated with chemotherapy who showed decreases in cognitive performance [chemo brain] also had reductions in the diversity of their gut microbiome,” Pyter said.

The researchers believe that treatments that improve the diversity of the gut microbiome may help ease or prevent chemo brain. More research needs to be done  to see if simple steps like taking probiotics  during chemotherapy can reduce the risk and severity of chemo brain.

“Side effects of chemotherapy are common and may reduce quality of life, but these side effects can be dismissed as ‘part of chemotherapy’ and therefore overlooked and under-treated,” Pyter said. “We believe that gut microbiome-focused interventions … may improve behavioral side effects of chemotherapy.”