Researchers across the country, including those at the University of Wisconsin, are working to understand Alzheimer’s disease, the most common form of dementia, affecting more than 20 million individuals, families and caregivers in the United States.

Despite decades of research, the cause of dementia due to Alzheimer’s disease remains unknown, and the burden of the disease continues to grow. According to the Alzheimer’s Institute at the UW School of Medicine and Public Health, as of 2017, 110,000 people in Wisconsin are living with Alzheimer’s and that number is expected to grow to 130,000 by 2025.

In the project Gut Microbiome Dynamics in Alzheimer’s Disease, a team of multidisciplinary researchers led by Barbara Bendlin, PhD, professor of medicine at the UW School of Medicine and Public Health, and Federico Rey, PhD, assistant professor of bacteriology, is exploring the role of gut bacteria in the development and treatment of Alzheimer’s disease.

Previous studies conducted at UW-Madison show that people with dementia due to Alzheimer’s disease have differences in their gut microbiome—the community of microbes, including bacteria, which reside in the gut— compared to people without dementia. Now, using a Collaborative Health Sciences Program grant, the researchers will extend this work by following participants in the Wisconsin Registry for Alzheimer’s Prevention (WRAP) study and the Wisconsin Alzheimer’s Disease Research Center (ADRC) over time to study how gut microbiome is related to brain changes.

Susan Gruber completes a memory exam with Susie Fernandez de Cordova
Research participant Susan Gruber completes a memory exam with Susie Fernandez de Cordova, BS, a research specialist at the Wisconsin Alzheimer’s Disease Research Center (ADRC). Both have experienced caring for loved ones with Alzheimer’s and recognize that studies like those taking place at the Wisconsin ADRC have the potential to help others, including future family generations, who may be at risk for Alzheimer’s disease.

Using an animal model of Alzheimer’s disease under controlled, germ-free conditions, they will determine which microbes are having an impact on the brain, and which mechanisms may underlie brain changes. Finally, in a first-of-its kind study, they will test whether it’s feasible to change the gut microbiome using a fecal transplant in people with dementia due to Alzheimer’s disease. Through these combined approaches, the researchers expect to maximize the expertise of investigators at UW to push the field of Alzheimer’s research.

Ultimately, these findings may lead to new treatments for Alzheimer’s disease. Drs. Bendlin and Rey are optimistic about the future. “We are just beginning to understand how gut microbes affect health in terms of disease and behavior,” says Dr. Rey.

By determining how a modifiable factor—the composition of the gut microbiome—affects the risk for Alzheimer’s disease, the researchers hope to open up a new area of research and discovery.

Adds Dr. Bendlin, “There is a lot of scientific excitement right now, and good things are happening in the field, including right here in Wisconsin. Thanks to a strong partnership between the people of Wisconsin and the WRAP and ADRC programs, researchers in Wisconsin are wellpositioned for this work.”

Both Dr. Bendlin and Dr. Rey agree that their research is driven by the families who have been impacted by this devastating disease. Says Dr. Bendlin, “We have been studying adult children of parents with Alzheimer’s disease for many years now. We want to find answers for them.”