Recent studies conducted on animals have shown that Alzheimer’s disease can be transmitted to young mice through the transfer of gut microbes, confirming a connection between the digestive system and brain health, according to Science Alert, citing the journal Scientific Reports. A new study further supports the theory that inflammation may be the mechanism through which negative effects on brain health occur. Psychologist Barbara Bendlin from the University of Wisconsin stated, “It has been found that individuals with Alzheimer’s have more gut inflammation, and brain imaging analysis showed that those with higher gut inflammation had higher levels of amyloid protein accumulation in their brains.”
Margot Hyston, a pathologist at the University of Wisconsin, along with an international team of researchers, tested fecal calprotectin, a marker for inflammation, in fecal samples from 125 individuals selected from two Alzheimer’s prevention studies. Participants underwent various cognitive tests upon enrollment in the study, along with interviews about family history and tests for high-risk Alzheimer’s genes. A subset of the group underwent clinical tests for signs of amyloid protein plaques, a common indicator of diseases responsible for neurodegenerative conditions. While calprotectin levels were generally higher among older patients, they were more pronounced in those with the characteristic amyloid plaques of Alzheimer’s. Additionally, levels of other Alzheimer’s biomarkers increased with inflammation levels, and memory test scores decreased as calprotectin levels rose. Even participants who had not been diagnosed with Alzheimer’s exhibited weaker memory scores with higher calprotectin levels.
Previous laboratory analyses have shown that chemicals from gut bacteria can trigger inflammatory signals in the brain. Other studies have also found increased gut inflammation in Alzheimer’s patients compared to control groups. Hyston and her colleagues suggest that changes in the microbiome lead to alterations in the gut that cause systemic inflammation. This inflammation is mild but chronic, causing slight and progressive damage that ultimately interferes with the sensitivity of body barriers.
Federico Rey, a professor of bacteria at the University of Wisconsin State, explained, “Increased gut permeability can lead to elevated levels of inflammatory molecules and toxins derived from the gut cavity in the blood, resulting in systemic inflammation, which can, in turn, weaken the blood-brain barrier and possibly promote neuroinflammation, thereby leading to neuronal injury and neurodegeneration.”
Researchers are currently conducting experiments on laboratory mice to determine whether dietary changes associated with increased inflammation can trigger a version of Alzheimer’s disease in mice. Despite decades of research, no effective treatment yet exists for the millions of people suffering from Alzheimer’s worldwide. However, with a greater understanding of biological processes, scientists are gradually getting closer to finding one.
