Scientists working to understand Alzheimer’s disease have found a closer connection between gut health and brain health, suggesting that the digestive system may play a role in the development of this condition.
Study Shows Alzheimer’s Passed Through Gut Microbes in Mice
In recent animal studies, researchers have shown that Alzheimer’s disease can be transferred to young mice through gut microbes. This finding strengthens the connection between our digestive system and brain health and suggests that the gut might affect how Alzheimer’s progresses in humans as well.
Gut Inflammation and Alzheimer’s Plaques Linked
In a 2023 study, researchers at the University of Wisconsin examined how inflammation in the gut might contribute to Alzheimer’s. Psychologist Barbara Bendlin, part of the research team, noted, “We found that people with Alzheimer’s have higher gut inflammation.” They also discovered that individuals with more gut inflammation tended to have higher levels of amyloid plaques in the brain. These plaques are known to be a hallmark of Alzheimer’s disease.
Testing Gut Inflammation Levels in Alzheimer’s Patients
To explore this connection, a team led by pathologist Margo Heston studied stool samples from 125 people in two Alzheimer’s prevention studies. They checked for fecal calprotectin—a protein associated with inflammation—and tested participants’ memory and cognitive skills. For those with early signs of Alzheimer’s, they found that higher gut inflammation correlated with poorer memory and cognitive test results.
The tests also revealed that individuals with amyloid plaques in their brains had increased levels of calprotectin, pointing to a possible link between inflammation in the gut and Alzheimer’s disease progression.
Understanding How Gut Inflammation May Affect the Brain
The study cannot yet confirm whether gut inflammation causes Alzheimer’s; for that, more detailed studies, like those on animals, are needed. However, past research has shown that certain chemicals produced by gut bacteria can send inflammatory signals to the brain. Studies also show that people with Alzheimer’s have more gut inflammation than those without the condition.
Heston and her team suspect that changes in the gut microbiome—meaning the balance of bacteria in the digestive system—could trigger ongoing, mild inflammation. This inflammation may gradually damage the body’s protective barriers, such as the blood-brain barrier, making it easier for harmful molecules and toxins to reach the brain.
How Gut Health Could Impact Alzheimer’s Disease
Federico Rey, a bacteriologist involved in the study, explains, “If gut inflammation weakens the blood-brain barrier, it could lead to brain inflammation and even nerve damage over time.” This weakened barrier may allow toxins from the gut to travel into the bloodstream, leading to systemic inflammation and potentially contributing to Alzheimer’s symptoms.
Future Research and Hope for Alzheimer’s Treatment
Researchers are now testing whether diet changes that increase gut inflammation could trigger Alzheimer’s-like symptoms in mice. While there’s still no effective treatment for Alzheimer’s, each new finding, like this link to gut health, brings scientists closer to understanding how the disease works. This research may eventually pave the way for new approaches to prevention and treatment.
Through studies like these, researchers aim to unlock more of Alzheimer’s mysteries, one step at a time, to improve the lives of millions worldwide.
This research has been published in Scientific Reports.
