Relevance of gut microbiota to Alzheimer's Disease (AD): Potential effects of probiotic in management of AD

The gut microbiota consists of a group of microorganisms required to support the gastrointestinal system. The microbiota-gut-brain axis is a dynamic bidirectional communication pathway that links cognitive and emotional perception with peripheral intestinal functions. The change in the architecture of gut microbiota increases the permeability of the intestine, activates the immune system, changes blood-brain barrier (BBB) permeability, increases proinflammatory mediators, and eventually causes neurodegeneration. The increased intestinal bowel upset and altered BBB permeability cause microbiota dysbiosis that leads to the release of amyloids and lipopolysaccharides. This further modulate NF-κB signaling and immense proinflammatory cytokines storm and cause loss of neurons. A growing body of experimental and clinical reports indicates the role of intestinal dysbiosis and microbiota-host interaction in neurodegeneration. The use of germ-free animals and animals with pathogenic infections and probiotics that affect the pathogenesis of Alzheimer's disease (AD) associated with gut microbiota is an ongoing developmental research area. The therapeutic indication of probiotics in modulating intestinal microbiota would be a therapeutic strategy in AD.  The purpose of the article is to explore how the gut-brain axis is linked to cognitive impairment and the use of probiotics to maintain gut microbial flora and prevent AD-like symptoms.