Impact of gut microbiota on the central nervous system relevance in neurodegenerative and psychiatric diseases

Introduction: The gut microbiota plays an important role in regulating the function of the gut-brain axis. Incorrect dietary habits promote the development of metabolic syndrome, which negatively affects the biodiversity of the microbiome. The aim of the study was to determine the influence of the gut microbiota on the function of the gut-brain axis and the development of mental and neurodegenerative diseases. Material and methods: A review of available literature was performed by searching the official databases PubMed and Google Scholar using the following keywords: metabolic syndrome, gut microbiome, metabolic microbiome, mental illness, neurodegenerative diseases with reference to original papers, meta-analyses and reviews in Polish, Ukrainian and English published in scientific journals and articles. Results: Studies evaluating the role of gut microbiota in the pathogenesis of psychiatric and neurodegenerative diseases show promising results, suggesting that gut microbiota influences brain function by modulating the gut-brain axis, the immune system, and neurotransmitter production. Despite the growing evidence implicating microbiota in the development of diseases such as depression, schizophrenia, Alzheimer's disease, and Parkinson's disease, study results often remain inconsistent, which may be due to methodological differences, heterogeneity of study populations, and sample size limitations. Conclusions: Further research on the influence of gut microbiota on the development of psychiatric and neurodegenerative diseases may contribute to a better understanding of the pathophysiology of these disorders and the discovery of new strategies for their treatment and prevention. Further research in this direction is needed to better understand the influence of gut microbiota on psychiatric and neurodegenerative disorders. Keywords: metabolic syndrome, mental illness, neurodegenerative diseases, gut microbiome, metabolic microbiome Abbreviations: International Diabetes Federation (IDF), short-chain fatty acids (SCFA), peptide YY (PYY), glucagon-like peptide-1 agonist (GLP-1), adenosine triphosphate (ATP), blood-brain barrier (BBB), central nervous system (CNS), Alzheimer's disease (AD), pathogen-associated molecular patterns (PAMPs), Toll-like receptors (TLRs), autism spectrum disorder (ASD), social anxiety disorder (SAD), bipolar disorder (BD), Young's Mania Rating Scale (YMRS), World Health Organization (WHO), Parkinson’s disease (PD), attention deficit hyperactivity disorder (ADHD)