Can bacteria control the human brain?

Nervous and neurodegenerative diseases are considered one of the most common groups among humanity, and the number of these diseases in the population is constantly increasing. At the same time, the prevalence of gastrointestinal and digestive system pathologies is also steadily growing. The literature contains numerous data on the relationship between the nervous system and the digestive system through a bidirectional microbiota-gut-brain axis, as well as connections via the circulatory and immune systems, among others. This work attempts to compile existing literature on this topic, summarize it, identify common patterns, and assess how strongly the gut can influence the course of various CNS disorders. It also aims to identify specific strains that may impact certain disorders and pathologies. Additionally, an effort was made to understand the mechanisms by which the microbiota affects the brain.