Proof That Alzheimer’s Is Linked To Your Gut Health
Proof That Alzheimer’s Is Linked To Your Gut Health
In recent years, researchers have been investigating whether there is a link between gut health and developing neurodegenerative diseases such as Alzheimer’s. Now, an international research team has confirmed that there is a connection.
What’s more, the team took a novel approach to provide proof: The investigators transplanted gut microbiota from people with Alzheimer’s into healthy young rats. The transference caused the rodents to develop symptoms of Alzheimer’s disease.
“Alzheimer’s is an insidious condition that there is yet no effective treatment for,” Sandrine Thuretone, a Professor of Neuroscience at King’s College London and one of the study’s senior authors, said in a news release. “This study represents an important step forward in our understanding of the disease, confirming that the make-up of our gut microbiota has a causal role in the development of the disease.”
The study, published in the journal, Brain, also noted that for the first time, Alzheimer’s symptoms can be transferred into a healthy young organism via the gut microbiota.
Yvonne Nolan, the study’s lead researcher and a professor and investigator in APC Microbiome Ireland at the University College Cork (UCC), explained that people are usually diagnosed with Alzheimer’s disease after they develop cognitive symptoms, and sometimes it may be too late, at least for the type of therapy currently available for the disease. However, Nolan added that understanding the role that gut microbes play during the early stages of dementia—before the potential onset of symptoms—”may open avenues for new therapy development” or even individualized intervention.
Professor John F. Cryan, UCC Vice President for Research and Innovation, who was also involved in the research, described the study as “exciting.” Cryan said it also aligns with the goals of UCC scientists who are working to develop strategies that promote healthy brain aging and advance treatments for Alzheimer’s by investigating how gut microbiota respond to lifestyle influences like diet and exercise.
What is Alzheimer’s disease?
Alzheimer’s is a progressive brain disorder that affects a person’s ability to think, learn new things, make decisions, and ultimately become serious enough to interfere with daily living activities.
Nearly seven million Americans age 65 and older are living with Alzheimer’s in 2024, according to the Alzheimer’s Association. Of that number, 73 percent are aged 75 and older.
Mild memory loss is one of the most common signs of Alzheimer’s disease in the early stage. According to the Alzheimer’s Association, other common signs of the disease include:
Changes in the ability to develop and follow a plan, such as following a familiar recipe or keeping track of monthly bills.
Difficulty completing familiar tasks, such as driving to a familiar location or organizing a grocery list.
Losing track of dates, seasons, and the passage of time.
Having trouble following or joining a conversation.
The Alzheimer’s Association noted that the disease is more than just memory loss, it also kills. Alzheimer’s was the fifth-leading cause of death among people aged 65 and older in 2021.
How The Study Was Conducted
The research team recruited 69 patients with Alzheimer’s disease and 64 cognitively healthy adults and collected blood and stool samples from them. The gut microbiota was provided via stool samples. The gut microbiome refers to the trillions of microbes found in the human gastrointestinal tract, such as bacteria, viruses, fungi, and other microorganisms.
The rats involved in the study were given antibiotics for seven days to deplete their own microbiota. After that, gut microbiota from Alzheimer’s patients was transplanted into 16 rats, and gut microbiota from cognitively healthy adults was transplanted into another group of 16 rats.
Ten days later, researchers started a battery of behavioral tests on the rats. After that, the investigators collected and analyzed samples of the rats’ gut tissues, brain tissues, blood, and feces.
The study noted that Alzheimer’s patients had more inflammation-promoting bacteria in their fecal samples, and these changes were directly associated with their degree of cognitive impairment. Rats receiving samples from these patients showed dementia-related changes that impacted their behavior, memory, and cognitive abilities.
The memory tests that researchers investigated relied on the growth of new nerve cells in the hippocampus, the region of the brain that involves memory, learning, and emotion.
“We saw that animals with gut bacteria from people with Alzheimer’s produced fewer new nerve cells and had impaired memory,” Nolan said in a news release.
Researchers say the study supports the emergence of the gut microbiome as a key target for investigation in Alzheimer’s disease due to its particular susceptibility to lifestyle and environmental influences.
“This collaborative research has laid the groundwork for future research into this area, and my hope is that it will lead to potential advances in therapeutic interventions,” Thuret said.
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