Dr. Auriel Willette and his team of researchers have been looking at how a biomarker, insulin-like growth factor binding protein 2 (IGFBP-2), may play a role in a person’s likelihood to develop Alzheimer’s disease. Photo by Ryan Riley/College of Human Sciences.

Iowa State researcher continues search for cause of Alzheimer’s

Dr. Auriel Willette and his team of researchers are continuing their look into how obesity-related problems are linked to metabolism and diabetes.

The outcomes of their latest research, published in the Journal of Alzheimer's Disease, point to a new biomarker, insulin-like growth factor binding protein 2 (IGFBP-2), and how it may play a role in a person’s likelihood to develop Alzheimer’s disease. IGFBP-2 helps to regulate energy metabolism by affecting blood glucose levels.

The researchers looked at markers for the protein in both blood and the fluid that surrounds the brain. Regardless of which fluid they looked at, what they determined is the level of the IGFBP-2 biomarker will predict if that individual will have a smaller hippocampus in his or her brain. The smaller the hippocampus, the less able that individual is to process blood sugar and form new memories, which is partly thought to be the cause of Alzheimer's disease. Willette’s previous research has shown the inability to process blood sugar is very important and may increase the risk of Alzheimer’s.

When IGFBP-2 biomarker levels were higher, this tripled the risk of that individual having some form of mild cognitive impairment or Alzheimer’s disease.

Willette said while the protein can be looked at in both brain fluid and in blood, a benefit of looking at it in brain fluid is you can additionally predict high levels of toxic proteins thought to cause Alzheimer's disease.

“One take-home is that while there's some overlap in what we see from the marker in blood or the brain fluid, there are some important differences about what type of fluid is good for tracking what kind of brain outcome,” Willette said. "It's much easier to draw blood, and it gives us a window into tracking how the brain changes during the course of Alzheimer's disease, but to track toxic proteins, you need the fluid that cushions the brain to do that."

If the higher levels of the biomarker are caused by being overweight, an individual can make lifestyle changes in order to get down to a healthier weight. As weight is lost, studies have shown memory is improved.

“If you can attribute causation to this, you can work to lower the levels,” Willette said. "If you have pre-diabetes or type 2 diabetes, it can negatively impact your memory. If you get that under control and you have moderate activity levels, it may improve your memory levels.”

Willette and his researchers will continue tracking the levels longitudinally, watching how they change over time and how well the various parts of the brain process blood sugar.

“Depending on how the levels change, we could track how much that benefits the brain and ultimately our ability to form and retain memories, which is critical in Alzheimer's disease,” Willette said.