Tangled Connection of Gut Microbiome and Alzheimer’s Disease

Several preclinical and clinical investigations have proved that the human gut microbiome plays a crucial role in the pathobiology of central nervous system (CNS) disorders. Recent studies suggest correlations between the altered gut microbiota and major Alzheimer’s Disease (AD). AD is characterized by the formation of Aβ plaques and neurofibrillary tangles. It is proposed that normalization of the gut microbiota alleviates AD. The imbalance in levels of normal gut microbiota has a crucial role in the pathogenesis of AD. Treatment strategies with certain antibiotics lead to the depletion of useful microbes and thereby induce AD-like effects in subjects. The microbiota is also involved in the synthesis of various neurotransmitters (NTs) like acetylcholine (ACh), 5-hydroxytryptamine (5-HT; serotonin), norepinephrine (NE), and dopamine (DA). Probiotics, prebiotics, synbiotics, and a healthy diet have been found to have positive benefits in controlling the etiology of AD. The control of brain-gut microbiota is developing as a potential AD therapy approach in light of the history of the limited therapeutic advantages of cholinesterase inhibitors. The importance of the brain-gut-microbiota axis in the development of AD is discussed in detail in this review, with an emphasis on the regulation of the gut microbiota as an important intervention for the treatment of AD.