A recent study relates the risk of Alzheimer’s to the gut microbiome. People with early indicators of the disease exhibited similar gut microbiome compositions that differed from those without early symptoms of the disorder.
The cause of Alzheimer’s disease is still a mystery to researchers because it is a complex ailment. According to a recent study, your gut bacteria may influence whether you get Alzheimer’s disease or not.
Researchers at Washington University School of Medicine have found that individuals with Alzheimer’s who are in the early stages of the disease – when brain changes have started but before cognitive symptoms are noticeable – have an assortment of bacteria in their intestines that are different from the gut bacteria of healthy individuals.
What is the new research about?
The scientists discovered that experiencing changes in gut bacterial populations may be an early sign of the disease. These alterations can sometimes develop years before the first indications of cognitive decline, such as memory loss and confusion.
The study, which examined the gut microbiome and composition of 164 senior citizens (aged 68 to 94) with normal cognitive function, was published in the journal Science Translational Medicine. To find those who might have early signs of Alzheimer’s, the researchers looked for the presence of the proteins amyloid and tau in the participants’ brains and had them take cognitive tests.
The scientists then compared the bacteria identified in the guts of 49 preclinical Alzheimer’s patients to those who did not show symptoms of Alzheimer’s proteins via fecal samples to determine if their microbiomes were distinct.
Researchers discovered that individuals with preclinical Alzheimer’s had distinct gut microbiomes from those who did not have the condition. In particular, individuals with preclinical disease frequently had larger quantities of bacteria responsible for degrading the amino acids arginine and ornithine, which contribute to protein synthesis. In general, those without preclinical Alzheimer’s had higher levels of microorganisms engaged in glutamate breakdown, which can preserve neurons.
The researchers also compared that information to risk factors such as a family history of Alzheimer’s, the participants’ age, genetics, and diabetes status, as well as brain images, to determine who was in the early stages of Alzheimer’s—and it was quite accurate.
The researchers stated that gut microbiome implications of preclinical Alzheimer’s neuropathology could help understand the disease’s etiology and find gut-derived markers of its risk.
How are the gut and brain connected?
Although your gut and brain are present in different regions of your body, research has revealed that they can influence one another. The gut-brain axis, which is essentially communication between your brain and gut, connects some activities in your intestine with your brain’s emotional and cognitive regions.
Here are some instances of your gut-brain axis in action: When you are stressed, you may experience diarrhea or constipation, or when you are nervous, you may experience butterflies in your stomach.
Researchers are still investigating how the gut-brain axis can affect a variety of disorders, including IBS (irritable bowel syndrome), depression, and obesity.
What connection exists between the gut and the brain in Alzheimer’s disease?
At this moment, nothing is certain. According to the co-author Beau M. Ances, it’s difficult to distinguish if the gut influences the brain or the brain influences the gut. That means it is unclear if the gut microbiota alterations are due to brain abnormalities or if the gut changes truly contribute to Alzheimer’s.
Some previous studies have also explored this connection.
- According to a previous study, chronic inflammation in the brain can increase the likelihood of developing Alzheimer’s by triggering cell damage and death.
- Another research has reported that high-fiber diets, including whole grains, fruits, and vegetables, may also help lower inflammation.
- According to the National Institute on Aging (NIA), specific gut bacteria turn the fiber in these foods into substances known as short-chain fatty acids (SCFAs), which can reduce inflammation and may enhance animal memory.
- A high-fiber diet, for example, changed the species of bacteria in the gut microbiome, increased the generation of SCFAs, and decreased the expression of some genes that govern inflammation in the brain, according to the findings of one mouse study published last year.
There are some ambiguities. The most recent study discovered that despite consuming essentially the same diet, persons with preclinical Alzheimer’s disease and those who were healthy had distinct gut microbes.
According to Dr. Ances, this research may eventually result in a diagnostic test that is more user-friendly and widely available.
People who have early signs of Alzheimer’s disease may also benefit from taking action to halt the disease’s course or perhaps prevent it.
In addition, Dr. Ances and his team have started a five-year follow-up research to determine whether variations in the gut microbiome are a cause or a consequence of the alterations in the brain that are characteristic of early Alzheimer’s.
- Ferreiro, A.L., Choi, J., Ryou, J., Newcomer, E.P., Thompson, R., Bollinger, R.M., Hall-Moore, C., Ndao, I.M., Sax, L., Benzinger, T.L. and Stark, S.L., 2023. Gut microbiome composition may be an indicator of preclinical Alzheimer’s disease. Science Translational Medicine, 15(700), p.eabo2984.
- Carabotti, M., Scirocco, A., Maselli, M.A. and Severi, C., 2015. The gut-brain axis: interactions between enteric microbiota, central and enteric nervous systems. Annals of gastroenterology: quarterly publication of the Hellenic Society of Gastroenterology, 28(2), p.203.
- Newcombe, E.A., Camats-Perna, J., Silva, M.L., Valmas, N., Huat, T.J. and Medeiros, R., 2018. Inflammation: the link between comorbidities, genetics, and Alzheimer’s disease. Journal of neuroinflammation, 15(1), pp.1-26.
- McGrattan, A.M., McGuinness, B., McKinley, M.C., Kee, F., Passmore, P., Woodside, J.V. and McEvoy, C.T., 2019. Diet and inflammation in cognitive ageing and Alzheimer’s disease. Current nutrition reports, 8, pp.53-65.
- Beyond the brain: The gut microbiome and Alzheimer’s disease. National Institute on Aging. https://www.nia.nih.gov/news/beyond-brain-gut-microbiome-and-alzheimers-disease. Published Online: 12th June, 2023. Accessed: 31st July, 2023.
- Vailati-Riboni, M., Rund, L., Caetano-Silva, M.E., Hutchinson, N.T., Wang, S.S., Soto-Díaz, K., Woods, J.A., Steelman, A.J. and Johnson, R.W., 2022. Dietary fiber as a counterbalance to age-related microglial cell dysfunction. Frontiers in Nutrition, 9, p.835824.
- Miller, K. An Early Sign of Alzheimer’s Disease May Be Lurking in Your Gut, Study Finds. https://www.prevention.com/health/memory/a44211806/gut-alzheimers-risk-link-bacteria-microbiome-study/. Published Online: 16th June, 2023. Accessed: 31st July, 2023.
- Altered gut bacteria may be early sign of Alzheimer’s disease. Washington University School of Medicine in St. Louis. https://medicine.wustl.edu/news/altered-gut-bacteria-may-be-early-sign-of-alzheimers-disease/. Published Online: 14th June, 2023. Accessed: 31st July, 2023.
- When Gut Bacteria May Be an Early Sign of Alzheimer’s Disease. Times. https://time.com/6287229/gut-alzheimers-connection-microbiome-bacteria/. Published Online: 14th June, 2023. Accessed: 31st July, 2023.