(HealthDay News) — Gut microbiome change is associated with cognitive decline during chemotherapy for patients with breast cancer, according to a study published online in the August issue of Brain, Behavior, and Immunity.

Lauren D. Otto-Dobos, PhD, from the Institute for Behavioral Medicine Research at the Ohio State University in Columbus, and colleagues analyzed fecal samples, blood samples, and cognitive measures from 77 patients with breast cancer before, during and after chemotherapy.

The researchers found that chemotherapy altered the gut microbiome community structure and increased circulating tumor necrosis factor-alpha (TNF-α). The chemotherapy-induced changes in microbial relative abundance and decreased microbial diversity both were associated with elevated circulating pro-inflammatory cytokines TNF-α and interleukin-6. Participant-reported subjective cognitive decline during chemotherapy was not associated with changes in the gut microbiome or inflammatory markers. A decrease in overall objective cognition, however, was associated with a decrease in microbial diversity, independent of circulating cytokines. Compared to individuals without cognitive decline, those with cognitive decline (35%) had unique taxonomic shifts in Faecalibacterium, Bacteroides, Fusicatenibacter, Erysipelotrichaceae UCG-003 and Subdoligranulum over the course of chemotherapy treatment.

“These results suggest that microbiome-related strategies may be useful for predicting and preventing behavioral side effects of chemotherapy,” the authors write.

One author disclosed ties to Scioto Biosciences.

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