The brain-gut-microbiota axis in the treatment of neurologic and psychiatric disorders

Abstract

The human gut microbiota is a complex ecosystem made of trillions of microorganisms. The composition can be affected by diet, metabolism, age, geography, stress, seasons, temperature, sleep, and medications. The increasing evidence about the existence of a close and bi-directional correlation between the gut microbiota and the brain indicates that intestinal imbalance may play a vital role in the development, function, and disorders of the central nervous system. The mechanisms of interaction between the gut-microbiota on neuronal activity are widely discussed. Several potential pathways are involved with the brain-gut-microbiota axis, including the vagus nerve, endocrine, immune, and biochemical pathways. Gut dysbiosis has been linked to neurological disorders in different ways that involve activation of the hypothalamic-pituitary-adrenal axis, imbalance in neurotransmitter release, systemic inflammation, and increase in the permeability of the intestinal and the blood-brain barrier. Mental and neurological diseases have become more prevalent during the coronavirus disease 2019pandemic and are an essential issue in public health globally. Understanding the importance of diagnosing, preventing, and treating dysbiosis is critical because gut microbial imbalance is a significant risk factor for these disorders. This review summarizes evidence demonstrating the influence of gut dysbiosis on mental and neurological disorders.

The Potential Role of Viral Persistence in the Post-Acute Sequelae of SARS-CoV-2 Infection (PASC)

“…Bacteria of microbiota can also stimulate a local immune response or metabolize the tryptophan, limiting its use as a precursor of indole, melatonin, and serotonin, low levels of which have been linked to neurological disorders [83]. Finally, microbiota can directly synthesize neurotransmitters [83].…”

“…Bacteria of microbiota can also stimulate a local immune response or metabolize the tryptophan, limiting its use as a precursor of indole, melatonin, and serotonin, low levels of which have been linked to neurological disorders [83]. Finally, microbiota can directly synthesize neurotransmitters [83]. The role of gut microbiota in neuronal health is highlighted by the association between gut dysbiosis and multiple neurological disorders, such as Alzheimer's disease, Parkinson's disease, multiple sclerosis, epilepsy, and sleep disorders [49].…”

Zeolite and Neurodegenerative Diseases

“…Only a few of the many supporting facts for the above hypothesis are as follows: Changes in the gut microbiome, correlating with the pathophysiology of AD, observed in both AD patients and mouse models of AD [ 24 , 25 , 27 , 28 , 29 ]; Studies, using antibiotic treatment [ 30 , 31 , 32 , 33 ] or mice bred in germ-free conditions and devoid of gut microbiota [ 34 , 35 , 36 ], showing a strong reduction in Aβ pathology and in microglial activation in AD mice models; Evidence that gut dysbiosis may lead to raised levels of circulating gut microbiota metabolites, including β-N-methylamino-L-alanine and microbial amyloids, the former, a gut cyanobacteria-produced neurotoxin, shown to cause hippocampal cell death and learning and memory deficits [ 37 , 38 , 39 ]; Studies on probiotic supplementation based on lactobacilli and bifidobacteria showing beneficial effects on cognitive function and other disease parameters in AD patients and animal models of AD and dementia [ 40 , 41 , 42 , 43 ]. …”

“…Changes in the gut microbiome, correlating with the pathophysiology of AD, observed in both AD patients and mouse models of AD [ 24 , 25 , 27 , 28 , 29 ];…”

Gut–Brain Axis: Focus on Sex Differences in Neuroinflammation

“…These microorganisms can have both beneficial and harmful effects on human health. A healthy balance among the GM is crucial for mental and physical health, as well as for preventing and treating several pathological conditions [3].…”