Scientists Demonstrate Gut Microbiome Connection with Transfer of Alzheimer’s to Healthy Animals


Scientists have previously suggested that the gut microbiome plays a role in causing Alzheimer’s disease, and this has now been confirmed.

A recent report from ScienceAlert covered a study by an international research team, confirming that the human memory impairments of Alzheimer’s patients were transmitted to healthy rats.

The study also revealed gut bacteria associated with cognitive impairment in Alzheimer’s patients.

These findings emphasize the critical role of the gut microbiome not only in Alzheimer’s research but also in other types of dementia, leading to a new approach for the treatment of these disorders.

Currently, the disease is treated at or near the beginning of the patient’s cognitive impairment, which is often too late. Dr. Yvonne Nolan, a neuroscientist at Ireland’s UCC, commented that analyzing gut microbes at the early stage of dementia may lead to new developments in therapy. Until now, there was only a supposition that gut microbiota might be a potential risk factor. Now, according to researchers, we have evidence.

About the Study

Dr. Nolan Thuret and his associates from KCL, UCC, IRCCS St. John of God Brescia, and Italy’s Research Centre conducted the study to determine how microbiota in the gut of people with Alzheimer’s affects their behavior and brain health.

The human part of the study included 69 participants with Alzheimer’s disease and 64 healthy human participants used as controls. Both groups donated blood for the study, and microbiota were obtained from stool samples provided by participants from each group.

Finally, sixteen adult rats had their microbiomes depleted and then replaced with microbiota from patients with Alzheimer’s. Additionally, sixteen rats with similarly depleted microbiomes were given gut microbiota transplanted from the healthy control group.

About the Tests

The rats underwent tests designed to analyze memory performance and other characteristics related to Alzheimer’s disorder. Rats that received transplants from people with Alzheimer’s exhibited faulty memory behavior. The study briefly mentioned the controversial process of hippocampal neurogenesis, creating new neurons that contribute to functions like learning, emotions, and creating new memories. The hippocampus is vulnerable to injury, disease, and stress such as Alzheimer’s.

The research team investigated memory tests relying on nerve cells in the brain’s hippocampus region. Rats with gut bacteria from Alzheimer’s patients had less nerve cell growth and memory problems. Impairments were more severe when the test scores of donors were low.

Researchers found modifications in the rats’ metabolites, such as enzymes and amino acids associated with growth, maintenance, and the normal functioning of cells. These changes could contribute to a decrease in neurons within the hippocampus. Although hippocampal neurogenesis is challenging to measure in humans, the team discovered that blood from people with Alzheimer’s reduced neurogenesis in human stem cells.

The team found a connection between gene expression levels in the blood of Alzheimer’s patients and their performance on cognitive tests, including the forms of bacteria found in their gut.

The team recommends future studies to address other factors affecting gut microbiota, such as health status, medication history, and lifestyle factors. Dr. Thuret hopes that the study will encourage advances in therapeutic intervention.


Rose Duesterwald

Rose Duesterwald

Rose became acquainted with Patient Worthy after her husband was diagnosed with Acute Myeloid Leukemia (AML) six years ago. During this period of partial remission, Rose researched investigational drugs to be prepared in the event of a relapse. Her husband died February 12, 2021 with a rare and unexplained occurrence of liver cancer possibly unrelated to AML.

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