New Insights Into the Link Between Gut Bacteria Makeup and Alzheimer's

A new meta-analysis from the Nevada Institute of Personalized Medicine at the University of Nevada, Las Vegas (UNLV) has revealed that some gut bacteria increase the risk of Alzheimer’s disease, while others have a protective effect. The study was published in Science Reports.

The importance of our gut bacteria

Our intestines are an environment where hundreds to thousands of different species of bacteria thrive, existing in a delicate balance that can be disrupted by diet, antibiotics and age.

“Most of the microorganisms in our intestines are considered good bacteria that promote health, but an imbalance of those bacteria can be toxic to a person’s immune system and linked to various diseases, such as depression, heart disease, cancer and Alzheimer’s disease,” said UNLV research professor Jingchun Chen.

A strong link exists between the gut and the brain, and research has shown that toxins or acids secreted by certain bacterial types can move through the intestinal lining and make their way to the brain.  Once there, these compounds can trigger a neuroinflammatory response by interacting with a gene called APOE, which affects brain health and may contribute to Alzheimer’s development.

Identifying bacterial groups associated with Alzheimer’s disease

The UNLV study examined data from previous reports on the connection between gut bacteria and the brain, identifying a significant correlation between four bacterial groups and an increased risk of Alzheimer’s. A further six types of bacteria were identified as having a protective effect.

The four bacteria that increased Alzheimer’s risk came from the Collinsella, Bacteroides, Lachnospira and Veillonella genera.

“With more research, it would be possible to identify a genetic trajectory that could point to a gut microbiome that would be more or less prone to developing diseases such as Alzheimer’s,” said study lead author Davis Cammann, “but we also have to remember that the gut biome is influenced by many factors including lifestyle and diet.”

The research team highlighted that more research is needed to complete the picture of the specific bacterial species that contribute to protection or susceptibility to Alzheimer’s and to build an understanding of how these bacteria are influenced by diet.

Reference: Cammann D, Lu Y, Cummings MJ, et al. Genetic correlations between Alzheimer’s disease and gut microbiome genera. Sci Rep. 2023;13(1):5258. doi: 10.1038/s41598-023-31730-5

This article is a rework of a press release from the University of Nevada, Las Vegas. Material has been edited for length and content.