Commentary: Does Severity of Alzheimer's Disease Contribute to Its Responsiveness to Modifying Gut Microbiota? A Double Blind Clinical Trial

Gut microbiota and its metabolites in Alzheimer's disease: from pathogenesis to treatment

Introduction

An increasing number of studies have demonstrated that altered microbial diversity and function (such as metabolites), or ecological disorders, regulate bowel-brain axis involvement in the pathophysiologic processes in Alzheimer's disease (AD). The dysregulation of microbes and their metabolites can be a double-edged sword in AD, presenting the possibility of microbiome-based treatment options. This review describes the link between ecological imbalances and AD, the interactions between AD treatment modalities and the microbiota, and the potential of interventions such as prebiotics, probiotics, synbiotics, fecal microbiota transplantation, and dietary interventions as complementary therapeutic strategies targeting AD pathogenesis and progression.

Survey methodology

Articles from PubMed and china.com on intestinal flora and AD were summarized to analyze the data and conclusions carefully to ensure the comprehensiveness, completeness, and accuracy of this review.

Conclusions

Regulating the gut flora ecological balance upregulates neurotrophic factor expression, regulates the microbiota-gut-brain (MGB) axis, and suppresses the inflammatory responses. Based on emerging research, this review explored novel directions for future AD research and clinical interventions, injecting new vitality into microbiota research development.

Gut Microbiota is an Impact Factor based on the Brain-Gut Axis to Alzheimer's Disease: A Systematic Review

Alzheimer's disease (AD) is a degenerative disease of the central nervous system. The pathogenesis of AD has been explained using cholinergic, β-amyloid toxicity, tau protein hyperphosphorylation, and oxidative stress theories. However, an effective treatment method has not been developed. In recent years, with the discovery of the brain-gut axis (BGA) and breakthroughs made in Parkinson's disease, depression, autism, and other diseases, BGA has become a hotspot in AD research. Several studies have shown that gut microbiota can affect the brain and behavior of patients with AD, especially their cognitive function. Animal models, fecal microbiota transplantation, and probiotic intervention also provide evidence regarding the correlation between gut microbiota and AD. This article discusses the relationship and related mechanisms between gut microbiota and AD based on BGA to provide possible strategies for preventing or alleviating AD symptoms by regulating gut microbiota.

Targeting gut microbiota to alleviate neuroinflammation in Alzheimer's disease

The gut microbiota came into focus within the last years regarding being associated with or even underlying neuropsychiatric diseases. The existence of the gut-brain-axis makes it highly plausible that bacterial metabolites or toxins that escape the intestinal environment or approach the vagal connections towards the brain, exert devastating effects on the central nervous system. In Alzheimer's disease (AD), growing evidence for dysbiotic changes in the gut microbiota is obtained, even though the question for cause or consequence remains open. Nevertheless, using modulation of microbiota to address inflammatory processes seems an attractive therapeutic approach as certain microbial products such as short chain fatty acids have been proven to exert beneficial cognitive effects. In this review, we summarize, contemporary knowledge on neuroinflammation and inflammatory processes within the brain and even more detailed in the gut in AD, try to conclude whom to target regarding human microbial commensals and report on current interventional trials.

Target Dysbiosis of Gut Microbes as a Future Therapeutic Manipulation in Alzheimer's Disease

Alzheimer’s disease (AD) is commonly an age-associated dementia with neurodegeneration. The pathogenesis of AD is complex and still remains unclear. The inflammation, amyloid β (Aβ), and neurofibrillary tangles as well misfolded tau protein in the brain may contribute to the occurrence and development of AD. Compared with tau protein, Aβ is less toxic. So far, all efforts made in the treatments of AD with targeting these pathogenic factors were unsuccessful over the past decades. Recently, many studies demonstrated that changes of the intestinal environment and gut microbiota via gut–brain axis pathway can cause neurological disorders, such as AD, which may be involved in the pathogenesis of AD. Thus, remodeling the gut microbiota by various ways to maintain their balance might be a novel therapeutic strategy for AD. In the review article, we analyzed the characteristics of gut microbiota and its dysbiosis in AD and its animal models and investigated the possibility of targeting the gut microbiota in the treatment of the patients with AD in the future.

Gut Microbiota: Implications in Alzheimer's Disease

Alzheimer’s disease (AD), the most common cause of dementia, is a neurodegenerative disease that seriously threatens human health and life quality. The main pathological features of AD include the widespread deposition of amyloid-beta and neurofibrillary tangles in the brain. So far, the pathogenesis of AD remains elusive, and no radical treatment has been developed. In recent years, mounting evidence has shown that there is a bidirectional interaction between the gut and brain, known as the brain–gut axis, and that the intestinal microbiota are closely related to the occurrence and development of neurodegenerative diseases. In this review, we will summarize the laboratory and clinical evidence of the correlation between intestinal flora and AD, discuss its possible role in the pathogenesis, and prospect its applications in the diagnosis and treatment of AD.