Authored by Amy Denney via The Epoch Times (emphasis ours),
Researchers recently discovered that they could give young, healthy animals Alzheimer’s disease by transferring the gut microbiome of human subjects with Alzheimer’s into germ-free rats.
Published on Oct. 18 in Brain, the findings solidify that the microbiome—the collection of bacteria, viruses, and fungi that live mostly in the colon—has a role in the development of Alzheimer's, the most common form of dementia, affecting 6.7 million Americans.
“This study represents an important step forward in our understanding of the disease, confirming that the makeup of our gut microbiota has a causal role in the development of the disease,” King’s College London neuroscience professor Sandrine Thuret, one of the study’s senior authors, said in a statement.
Our intestines are home to trillions of these microscopic bugs, which mostly live in symbiosis with the human body. Many factors, including antibiotics, glyphosate, medications, and stress, have been proven to kill beneficial microorganisms and cause an imbalance often referred to as dysbiosis.
Exactly what causes the microbial shift in people with Alzheimer’s disease is unclear.
“Bigger picture, it is likely that no one factor, food or lifestyle change will, on its own, reduce the risk of developing cognitive decline as we age," Percy Griffin, Alzheimer’s Association director of scientific engagement, said in a statement to The Epoch Times.
"Although this work is intriguing, it is still very preliminary. Larger studies in animal models, and then in humans, are required to make generalizations on what can be done in this area to reduce the risk of developing Alzheimer’s.”
There were 69 healthy control subjects and 64 Alzheimer’s patients in the study. Patients with Alzheimer's had a higher abundance of inflammation-promoting bacteria in fecal samples, and these changes were associated with their cognitive status. Those traits were then found through a battery of behavior tests in only the rats that were given transplants from Alzheimer's patients.
“The memory tests we investigated rely on the growth of new nerve cells in the hippocampus region of the brain. We saw that animals with gut bacteria from people with Alzheimer’s produced fewer new nerve cells and had impaired memory,” lead author professor Yvonne Nolan said.
Alzheimer’s disease's link to the microbiome has already been explored in recent studies, although it’s been largely unclear whether the disease caused the dysbiosis or if—as this research indicates—alterations in the intestinal community cause symptoms of dementia.
Mr. Griffin, who holds a doctorate in molecular cell biology from Washington University in St. Louis, noted that studies in rats don’t always indicate that similar findings will occur in the human body. To build credibility, the research needs to be replicated, he said.
“This is an interesting study that adds to our growing understanding of how the bacteria in the gut may contribute to risk for Alzheimer’s disease. But this study is in rats, and rats are not people,” he said. “That said, these findings demonstrate a possible role for gut bacteria in affecting the areas of the brain that are (a) associated with memory and (b) involved in Alzheimer’s disease.”
Presymptomatic Identification of Disease
However, dysregulation of the microbiome could give early insights into disease, which has long been associated with systemic inflammation.
“Understanding the role of gut microbes during prodromal–or early stage—dementia, before the potential onset of symptoms may open avenues for new therapy development, or even individualized intervention,” Ms. Nolan said. “People with Alzheimer’s are typically diagnosed at or after the onset of cognitive symptoms, which may be too late, at least for current therapeutic approaches.”
A study in Cell Death and Differentiation in 2019 found that impaired neurogenesis is a biomarker for Alzheimer’s. Neurogenesis is the continued development of neurons that occurs in two parts of the adult brain, including the hippocampus, which is responsible for learning and memory.
“Remarkably, it has been recently described that neurogenesis persists in cognitively healthy people until the end of life, but drops off dramatically as AD [Alzheimer's disease] pathology takes hold,” the study reads.
New research is showing that neurogenesis impairment begins before amyloid-plaque formation, the clumping of protein pieces found in the brains of Alzheimer's patients. Taken together, neurogenesis and the microbiome offer evidence that suggests that the disease can be identified in stages in which its development could be halted before symptoms set in.
Alzheimer's is the most common cause of dementia, which is marked by memory loss and other cognitive disabilities that interfere with daily life. According to the Alzheimer’s Association, 1 in 3 people are likely to develop Alzheimer's.
“Alzheimer’s is an insidious condition that there is yet no effective treatment for,” Ms. Thuret said. “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.”
What's Influencing the Microbiome?
The microbiome is a key area of Alzheimer's research worldwide due to its vulnerability to lifestyle and environmental factors.
The Alzheimer’s Association is leading the U.S. POINTER study, which finished recruitment in March and is expected to begin reporting results in 2025. The two-year clinical trial is evaluating whether lifestyle interventions that simultaneously target many risk factors can protect cognitive function in older adults who are at increased risk for cognitive decline.
“All of our body systems are interconnected, and it is important to understand how they work together to impact the risk and resilience against Alzheimer’s,” Mr. Griffin said. “For ongoing and overall good health, people should speak to their doctors about their digestive health and ways to keep it operating healthfully, such as drinking enough water and eating enough dietary fiber.”
He’s hopeful that the POINTER study will help determine a sustainable, community-based lifestyle intervention recipe to reduce the risk of developing cognitive decline as we age.
It’s the kind of work that some organizations have already been doing, even without studies that fill in the blanks of causation with Alzheimer’s disease.
Dr. Dale Bredesen has been reversing symptoms with a research-based protocol. Sharp Again Naturally offers programs that address nutrition and create a healthy gut microbiome to help participants preserve and improve their brain health.
The new study is hopeful, according to the board chair of Sharp Again Naturally, Steve Ledvina, who’s also a certified health and wellness coach and the founder of Knowing Alz.
“This exciting study extends the evidence for the strong connection between the gut microbiome and the brain and suggests poor gut health has a causal role in Alzheimer's symptoms,” Mr. Ledvina wrote in an email to The Epoch Times. “For individuals, it emphasizes that intentionally maintaining or healing our guts and promoting a healthier gut microbiome is essential to keeping our brains healthy.”
He said potential causes of poor gut health include excessive sugar or alcohol consumption, antibiotics or other gut-disrupting medicines, and stress.
“We can promote our gut health by eating prebiotic fiber in vegetables like asparagus and artichoke hearts and probiotics like sauerkraut, kimchi, and low-sugar kombucha,” Mr. Ledvina said.