The immune system, neurological system, neurotransmitters, and hormones constantly communicate between the gut and the brain. Alterations in the gut, particularly the gut microbiome, can alter the brain, resulting in behavioral and cognitive changes. A healthy and diversified microbiome acquired by a high fiber diet or probiotic or prebiotic therapy has been linked to cognitive gains.

Gut dysbiosis and a decrease in microbial diversity, which can be caused by a Western diet or antibiotic treatments, have been linked to cognitive decline and memory loss. The immune system, metabolites, gut hormones, and neurotransmitters are all plausible mechanisms by which these alterations in the gut operate to change cognition.