Clinical insights into the mechanisms of infectious microbes and microbiota in chronic neurologic and psychiatric diseases

Chronic neurologic and psychiatric diseases such as schizophrenia, depression, Parkinson's, and Alzheimer's are increasingly linked to infectious microorganisms and gut microbiota. This review explores how pathogenic microorganisms and microbial communities impact neuropsychiatric, neurodegenerative, and neuroinflammatory processes, highlighting the gut-brain axis' crucial communication network in influencing behavior and brain function. Infectious agents like bacteria, viruses, and fungi cause disease by causing neurotoxic reactions, disrupting the blood-brain barrier, and activating neuroinflammatory cascades. Gut dysbiosis impacts immunological homeostasis and neural transmission by altering the synthesis of metabolites from microorganisms, such as short-chain fatty acids and neurotransmitter precursors. Neurodegeneration and psychiatric diseases are influenced by molecular mechanisms such as toll-like receptor signaling, microglial activation, and mitochondrial dysfunction. This review highlights the potential of microbiota-targeted treatments such as probiotics, prebiotics, and microbiome transplantation as novel treatments for chronic diseases. Understanding the intricate interactions between infectious microorganisms, microbiota, and the central nervous system enables the formation of precision medicine strategies to challenge the rising incidence of neurologic and psychiatric diseases. Future research should explore causal relationships and identify specific microbial biomarkers to enhance early diagnosis, prevention, and personalized treatment plans.