The Link Between Gut Health and Alzheimer’s – Scientific Research


How to Keep Your Gut Microbiome Healthy for a Stronger Brain

Alzheimer’s is the leading cause of dementia, a condition that is devastating for those affected, their loved ones, and their carers. With one in three people born today likely to develop dementia in their lifetime, scientists have been exploring potential links between gut health and Alzheimer’s that could help uncover approaches for new treatments. This includes work to better understand the health of our gut and the brain.

The gut is host to a community of bacteria called the intestinal microbiome. The precise make-up of the microbiome differs between individuals, in both the types and quantities of bacteria present. This microbial composition can have far-reaching effects on other parts of our body and emerging evidence is suggesting a relationship with brain health and the risk of diseases like Alzheimer’s.

Scientific Research on Gut Bacteria, Inflammation, and Alzheimer’s Disease

New research, which hasn’t yet been peer-reviewed, presented at the Alzheimer’s Research UK Conference 2022, highlights newly identified links between gut health and Alzheimer’s disease, inflammation, and brain changes associated with Alzheimer’s disease.

Dr. Edina Silajdžić, a postdoctoral fellow working in the research lab of Prof Sandrine Thuret from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London analyzed blood samples from 68 people with Alzheimer’s and a similar number of people without the disease. This study, in collaboration with the Biological Psychiatry Laboratory at IRCCS, Italy coordinated by Dr Annamaria Cattaneo, revealed a distinct gut bacteria makeup in people with Alzheimer’s as well as more inflammation markers in their stool and blood samples.

Furthermore, another new study in the Journal of Alzheimer’s Disease reveals a seemingly robust link between the neurogenerative illness and compounds released by gut bacteria. According to the study authors, these findings provide “indisputable” evidence that the intestinal microbiota plays a significant role in the development of Alzheimer’s.

The so-called gut-brain axis has been the subject of much scientific investigation and debate in recent years, with an increasing amount of data indicating that the microscopic inhabitants of our entrails directly influence our central nervous system. This two-way channel of communication allows the brain to send chemical messages to the gut in order to control appetite and digestion, while it is thought that the bacteria therein release a range of metabolites that impact brain function.

Gut Microbiome’s Role in Alzheimer’s Disease

This has led to speculation that the make-up of a person’s microbiome could contribute to their likelihood of developing Alzheimer’s disease, although this link has never been confirmed. In an attempt to put the debate to bed, the authors of the new study recruited 89 volunteers between the ages of 65 and 85, some of whom were healthy while others suffered from varying degrees of cognitive decline. Using positron emission tomography (PET), the team scanned participants’ brains for signs of amyloid plaques, which are a key indicator of Alzheimer’s, while also collecting blood samples in order to search for gut bacteria metabolites.

Results indicated that those with more amyloid plaques in their brains tended to have higher levels of lipopolysaccharides in their blood. Found on the outer membrane of certain bacteria, these molecules are known to stimulate the formulation of amyloid plaques while also increasing inflammation in the brain.

Similarly, short-chain fatty acids such as acetate and valerate were found to be elevated in the blood of those suffering from Alzheimer’s. Both of these are released by certain gut bacteria and have been associated with inflammation in the brain.

Role of Compounds That Interfere with Endothelial Cells

Other compounds that are known to interfere with endothelial cells and disrupt the integrity of the blood-brain barrier were also present in larger concentrations in people with high levels of amyloid plaques. Indicating that this may represent another avenue by which gut microbiota influences the development of the disease.

In contrast, lower levels of amyloid plaques were correlated with higher concentrations of a short-chain fatty acid called butyrate. Which is known to protect neurons by reducing inflammation in the brain.

However, while the confirmation of a link between gut health and Alzheimer’s is significant, co-author Giovanni Frisoni insists that “we shouldn’t be too quick to rejoice,” as this knowledge is unlikely to lead to a cure for neurodegenerative diseases.

Instead, it could enable more effective identification of individuals who are at risk of developing such a condition, allowing for earlier interventions.

Final Verdict:

In the meantime, we could all take preventative action which means doing all we can to ensure that we are consuming a gut-friendly diet, that is both rich in plant-based foods and highly varied, to ensure that our gut bacteria is as plentiful and diverse as possible.

If you would like to know more about eating for immunity and nutritional eating for long-term wellness you may be interested in attending our Nutritional Eating cookery class.


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