Jan 10 2021

Connection between Gut Microbiota and Alzheimer’s Disease

Published by at 1:37 pm under Dementia

New research unlocks the connection between gut microbiota and Alzheimer’s Disease.1*
Researchers are one step closer to understanding how gut bacteria play a role in the development of this degenerative brain disease.1*

There is new research on Alzheimer’s disease and it involves the microbiome. For several years now, researchers have suspected a true connection between the gut and the development of Alzheimer’s, but answers remained elusive. Now, new information from researchers in Europe confirms what they have suspected all along… there is indeed a connection. 1*

Alzheimer’s disease is a progressive and incurable degenerative brain disease that affects nearly 5.5 million Americans every year. Those affected experience loss of memory and cognitive thinking skills and, over time, they lose the ability to carry out even the simplest tasks. The symptoms first appear in the mid-60s for people with late-onset Alzheimer’s, and in the rare case of early-onset Alzheimer’s, symptoms appear between the ages of 30 to mid-60s. (1,2)*

Alzheimer’s disease is so devastating because it not only affects the person with the disease, but it also affects their families and friends as they bear witness to their loved ones decline. People with Alzheimer’s get confused, frustrated, and in some cases angry as they can’t find the right words to express themselves. They experience vision and spatial issues, and their reasoning and judgment become impaired. Everyday tasks like cooking, driving or paying bills become confusing and they may repeat questions, lose items, or put things in the wrong place and can get easily lost themselves.  These changes are scary which causes them to become worried, paranoid, angry, and in some cases violent. If you have ever had a loved one with Alzheimer’s, you know the challenges. There is an excellent documentary that chronicles the decline of country music legend Glen Campbell who lived with Alzheimer’s. It also shows the effect it had on his family. 2

While dementia comes in many forms, Alzheimer’s disease is the most common. It is named after Dr. Alois Alzheimer, who discovered the degenerative disease after studying the brain of one of his deceased patients, a woman who had died of an ‘unusual mental illness’. She had experienced memory loss, unpredictable behavior, and trouble with formulating sentences. Upon examination of her brain tissue, he found she had “abnormal clumps” (which have since been identified as amyloid plaques) and “tangled bundles of fibers” (now called neurofibrillary, or tau, tangles).2*

Some of the main physiological identifiers found on PET scans of Alzheimer’s patients are these plaques and tangles in the brain. Another is the loss of connection between nerve cells or neurons in the brain. It is the neurons that transmit messages between different areas of the brain, and also from the brain to muscles and organs in the body. Other complex brain changes are believed to play a role in Alzheimer’s disease. The initial damage to the brain occurs in the hippocampus, the part of the brain essential in forming memories. As neurons die, other parts of the brain are affected and during the final stages of Alzheimer’s, the damage is widespread as the brain tissue shrinks significantly.2*

In recent years, scientists have come to believe that there is a connection between gut microbiota diversity and the degeneration of the brain. Multiple research studies from scientists all over the world have tried to hone in on just how this connection might work, what bacteria are involved, how they affect the brain, and how they metabolize in the brain once they get there.

In one research study from the Wisconsin Alzheimer’s Disease Research Center, a medical student named Nick Vogt compared the gut diversity and the spinal fluid of those with and without dementia which resulted in showing those individuals with Alzheimer’s and Parkinson’s lacked the microbial diversity that their healthy counterparts possessed. Research has also shown that “…patients with dementia-like conditions, including mild cognitive impairment and Alzheimer’s disease, have dysbiosis compared to those without memory problems…”  (1,3)*

We have long discussed the gut-brain axis, and this theory fits into this connection. Just as the brain sends signals to the gut that influence digestion, gut microbes send stress signals to the brain through this same axis, the vagus nerve. All of this early research suggests a disrupted microbiome contributes to the development of neurological disorders by negatively affecting the gut-brain axis. However, the initial cause of microbiome disruption in those with neurological conditions has not been known. (1,4)*

Recently, a team of researchers from Geneva and Italy has confirmed this correlation, showing that there is a connection between an imbalance in gut microbiota and the development of amyloid plaques in the brain, which is at “…the origin of neurodegenerative disorders that is characteristic of Alzheimer’s disease…”1*

These researchers found that proteins produced by certain intestinal bacteria which have been identified in the blood of Alzheimer’s patients, “…could indeed modify the interaction between the immune and the nervous systems and trigger the disease…” 1*

Giovanni Frisoni, Neurologist and professor at the Department of Rehabilitation and Geriatrics of the UNIGE Faculty of Medicine and the director of the HUG Memory Centre along with his research laboratory has devoted many years exploring the influence of gut microbiota on the brain, especially on neurodegenerative diseases.”… “We have already shown that the gut microbiota composition in patients with Alzheimer’s disease was altered, compared to people who do not suffer from such disorders,” he explains. “Their microbiota has indeed a reduced microbial diversity, with an over-representation of certain bacteria and a strong decrease in other microbes. Furthermore, we have also discovered an association between an inflammatory phenomenon detected in the blood, certain intestinal bacteria, and Alzheimer’s disease; hence the hypothesis that we wanted to test here: could inflammation in the blood be a mediator between the microbiota and the brain? “…”1*

Just as intestinal bacteria can affect the immune system as well as the relationship between the immune system and the nervous system, it can also influence the functioning of the brain, via the vagus nerve, and promote neurodegeneration through these pathways.”… Lipopolysaccharides, a protein located on the membrane of bacteria with pro-inflammatory properties, have been found in amyloid plaques and around vessels in the brains of people with Alzheimer’s disease. In addition, the intestinal microbiota produces metabolites — in particular some short-chain fatty acids — which, having neuroprotective and anti-inflammatory properties, directly or indirectly affect brain function…”1*

According to researcher Moira Marizzoni, “To determine whether inflammation mediators and bacterial metabolites constitute a link between the gut microbiota and amyloid pathology in Alzheimer’s disease, we studied a cohort of 89 people between 65 and 85 years of age. Some suffered from Alzheimer’s disease or other neurodegenerative diseases causing similar memory problems, while others did not have any memory problems.” Using PET imaging, they “…measured their amyloid deposition and then quantified the presence in their blood of various inflammation markers and proteins produced by intestinal bacteria, such as lipopolysaccharides and short-chain fatty acids….”1*

Marizzoni claims, “Our results are indisputable: certain bacterial products of the intestinal microbiota are correlated with the number of amyloid plaques in the brain. Indeed, high blood levels of lipopolysaccharides and certain short-chain fatty acids (acetate and valerate) were associated with both large amyloid deposits in the brain. Conversely, high levels of another short-chain fatty acid, butyrate, were associated with less amyloid pathology.”…”1*

This research shows the clear connection between particular proteins found in gut microbiota and cerebral amyloidosis “…through a blood inflammatory phenomenon…” Now, the next step for scientists and researchers is to identify specific bacteria, or a group of bacteria, at the core of this phenomenon.1*

These results, which are to be published in the Journal of Alzheimer’s Disease, make it possible to imagine that new preventative strategies could be developed by controlling or having an influence on the microbiota of those at risk for developing Alzheimer’s disease.1*

Next time we will look at what we should do in the meantime to protect our guts and our brains through diet, exercise, fasting, and probiotic supplementation. Body Biotics™ Bio-Identical SBO Probiotics Consortia™ is key to keeping the gut diverse and the brain and body healthy. We look forward to new developments in this fascinating area of research.

Until next time, healthiest wishes!





  1. https://www.sciencedaily.com/releases/2020/11/201113124042.htm
  2. https://www.nia.nih.gov/health/what-alzheimers-disease
  3. https://youtu.be/a1A05ql6Yyw
  4. https://theconversation.com/your-gut-microbiome-may-be-linked-to-dementia-parkinsons-disease-and-ms-144367
  5. https://www.health.com/nutrition/brain-health-intermittent-fasting


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