Research into the microbiome is yielding some positive new potential treatment options for Alzheimer’s disease, according to George T. Grossberg, MD from St. Louis University.
Early evidence suggests that the gut-brain axis can affect cognition. In an animal model study, transferring the microbiota of a mouse with Alzheimer’s disease to one that had been bred to be germ-free resulted in cognitive decline – but there was no cognitive decline for germ-free mice that received a microbiota transplant from a mouse in a healthy control group. Results from another animal study showed that transferring healthy microbiota from a mouse model into a mouse with Alzheimer’s disease reduces amyloid and tau pathology. “The conclusions of these studies seems to be that microbiota mediated intestinal and systemic immune changes or aberrations seem to contribute to the pathogenesis of Alzheimer’s disease in these mouse models,” Dr. Grossberg said. “Consequently, restoring the gut microbial homeostasis may have beneficial effects on Alzheimer’s disease treatment.”
Periodontal disease also might be linked to Alzheimer’s disease, Dr. Grossberg said. Several studies have shown gingipains secreted from Porphyromonas gingivalis, which contribute to inflammation in the brain, have been found in cadavers of patients with Alzheimer’s disease. “There’s reason to think that the same changes may be occurring in the human brain with periodontal disease,” he said.
The relationship also might extend to the gut microbiota and the central nervous system. “There seems to be a direct communication, a direct relationship between normal gut physiology and healthy central nervous system functioning, and then, when you have abnormal gut function, it may result in a variety of abnormal central nervous system functions,” Dr. Grossberg said.
Studies that have examined a relationship between Alzheimer’s disease and gut microbiota have highlighted the potential of probiotics and prebiotics as a method of restoring the gut microbiota. Probiotics are popularly sold in health food aisles of grocery stores, and prebiotics are available in foods such as yogurts, tempeh, sauerkraut, and kimchi, as well as in drinks such as Kombucha tea. The effectiveness of probiotics and prebiotics also are being examined in randomized, controlled trials in patients with mild cognitive decline and mild Alzheimer’s disease, Dr. Grossberg said.
One therapy, Sodium oligomannate, a marine algae–derived oral oligosaccharide, has shown effectiveness in remodeling gut microbiota and has been approved in China to treat patients with mild or moderate Alzheimer’s disease. Currently, no approved gut microbiota therapies are approved in the United States to treat Alzheimer’s disease; however, encouraging use of a prebiotic, a probiotic, or a Mediterranean diet is something clinicians might want to consider for their patients.
“The fact that we’re studying these things has really led to the notion that it may not be a bad idea for people to consume these healthy bacteria in later life, either as a way to prevent or delay, or to treat Alzheimer’s disease,” Dr. Grossberg said. “There’s really no downside.”