Title: New Study Reveals Genetic Connection Between Gut Microbes and Alzheimer’s
Subtitle: Research Provides Insight into the Role of Microbiota-Gut-Brain Axis in Neurodegenerative Conditions
Date: April 2023
Scientists have long suspected that the intricate relationship between the brain, the gut, and the microbes living in the digestive system plays a crucial role in the development of neurodegenerative disorders, including Alzheimer’s disease. New research published in Scientific Reports by a team of US researchers sheds light on the genetic connection between Alzheimer’s and the composition of gut bacteria.
In the largest genome-wide association study of human gut microflora to date, the researchers aimed to unravel the complex web of interactions between gut bacteria and Alzheimer’s disease. Their analysis, based on thousands of participants, discovered not only a genetic link between different genera of gut bacteria and the diagnosis of Alzheimer’s, but also a connection between these microbes and a genetic risk factor for the disease.
The findings of this study further emphasize the importance of genetic factors and the role of inflammatory gut microflora in maintaining healthy brain function. During early development, the body is colonized by an array of bacteria, fungi, and viruses that coexist with the immune system. This delicate balance, although mostly beneficial, can be disrupted by shifts in the immune system or changes in the gut microbiota due to various factors, such as diet.
The complex interplay between gut microflora, the immune system, and neurological functioning has been the focus of research in recent years as scientists strive to understand the mechanisms behind the degeneration of brain tissue and the resulting cognitive decline in Alzheimer’s patients.
Previous studies have hinted at a reduction in gut microbial diversity in individuals with Alzheimer’s, as well as the ability of certain gut bacteria to release chemicals that trigger inflammatory signals in the brain. Complicating matters is a gene called apolipoprotein E (APOE), specifically the E4 variant, which is associated with a genetic risk for Alzheimer’s. Scientists suspect that this gene variant may influence the composition of the gut microbiota.
In their investigation, the research team examined detailed records of 119 bacterial genera obtained from the MiBioGen Consortium study. The initial search uncovered 20 genera suspected of contributing to Alzheimer’s development, and a more focused analysis identified 10 genera, with six being less common in diagnosed patients and four being more prevalent.
Of these 10 bacterial genera, four were found to have a relationship with the APOE allele associated with an increased risk of Alzheimer’s disease. One notable genus, Collinsella, was connected not only to Alzheimer’s and the APOE variant but also to rheumatoid arthritis, atherosclerosis, and Type-2 diabetes. The researchers suggest that Collinsella’s ability to promote inflammatory hormone production and increase gut permeability could contribute to neurological damage.
Additionally, the study highlighted an association between high levels of Collinsella and elevated cholesterol and low-density lipoprotein (LDL) in healthy adults, further indicating a potential link between gut microbes, fat metabolism, and neurodegeneration. The research also unveiled the existence of “protective” bacterial groups that may counteract inflammation.
Alzheimer’s disease, the most common form of dementia, is projected to affect 150 million people worldwide by the middle of the century due to an aging global population. Understanding the origins and pathology of this devastating illness is crucial for developing effective treatment and prevention strategies.
This groundbreaking research provides valuable insights into the genetic connection between gut microbes and Alzheimer’s disease. Further investigations are necessary to fully comprehend the mechanisms at work in the gut and explore potential avenues for therapeutic interventions.
Disclaimer: This article was originally published in April 2023.