Impacts of breast cancer and chemotherapy on gut microbiome, cognitive functioning, and mood relative to healthy controls

Women diagnosed with breast cancer undergoing chemotherapy experience cognitive impairment, symptoms of anxiety and depression, and physical side effects including disruption in the diversity and community composition of the gut microbiome. To date, there is limited research exploring the associations among these specific challenges. The present cross-sectional study explored the associations of self-reported cognitive functioning, depression, and anxiety symptoms, and gut microbiome diversity and community composition in women who were diagnosed with and undergoing chemotherapy treatment for breast cancer (BC) compared to cancer-free healthy controls (HC). The BC group displayed higher rates of cognitive dysfunction ( p < 0.001) and depressive symptoms ( p < 0.05) relative to HC. There was a significant difference in microbiome community composition between BC and HC, particularly characterized by a decreased relative abundance of the mucin-degrading genus Akkermansia in BC compared to HC ( p < 0.05). Association models identified significant associations among group, cognitive, depression, and microbiome variables ( p < 0.001). Overall, the study identified that BC participants experienced significant differences in self-reported cognitive functioning, self-reported depression symptoms, microbiome community composition, and mucin-degrading bacteria of the gut-mucosal barrier, relative to HC. The present study is consistent with the hypothesis that gut microbiome community composition impacts a woman’s experience with breast cancer and treatment suggesting that microbiome-based interventions have potential for improving quality of life outcomes in individuals with breast cancer.