The effect of intestinal microbiota on the occurrence of mental disorders and neurodegenerative diseases

Abstract

The pathogenesis of mental disorders and neurodegenerative diseases may be related to the composition of gut microbiota. Communication between the intestines and the brain is possible through the gut-brain axis and takes place via endocrine, neuronal and immunological mechanisms. Presented here is a summary of the current state of knowledge on the relationship between the composition of the gut microbiota and the occurrence of mental disorders and neurodegenerative diseases. The composition of human gut microbiota during its life is subject to fluctuations. Gut bacteria perform many functions that are beneficial to the health of the host. Under the influence of environmental factors, gut dysbiosis may occur - a state of qualitative and quantitative disturbance of gut bacterial biota. There are clear differences between the composition of the gut microbiota of people diagnosed with mental disorders and the composition of the gut microbiota of healthy people. In such conditions as depression, schizophrenia or autism, intestinal dysbiosis is observed, which compromises the integrity of the intestinal barrier, followed by the displacement of microorganisms and their products into the general circulation. In people diagnosed with neurodegenerative diseases (Alzheimer's disease, Parkinson's disease) the composition of gut bacterial biota is different compared to healthy people. Selected types of bacteria, via the gut-brain axis, can affect brain processes. There are relationships between the composition of the gut microbiota and the occurrence of mental disorders and neurodegenerative diseases in humans. Usually, they are associated with intestinal dysbiosis and leaky gut syndrome.