Are Diabetes and Alzheimer’s Disease Linked?

Authors of a new study say they’ve discovered a connection between diabetes and Alzheimer’s disease that offers more evidence that elevated blood sugar may have an impact on Alzheimer’s.

In an effort to understand how elevated blood sugar might affect Alzheimer’s risk, a team led by researchers at the Washington University School of Medicine infused glucose into the bloodstream of mice bred to develop a condition comparable to Alzheimer’s. The authors found that elevated glucose in the blood can quickly increase levels of amyloid beta, which is a key element of Alzheimer’s patients’ brain plaques, the buildup of which is considered to be an early driver of the changes that the disease causes in the brain.
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According to the investigators, doubling glucose levels in the brain increased amyloid beta levels by 20% in young mice, with that number rising to 40% when the authors repeated the experiment in older mice that had already developed brain plaques. The researchers also found that a rise in blood glucose increased neuron activity in the brain, which aided production of amyloid beta.

While the study was conducted on mice, “we found that increases in glucose to levels just 2 to 3 times higher than normal not only increased amyloid-beta levels, but they also increased nerve cell activity above normal,” says David M. Holtzman, MD, a professor and chairman in the department of neurology at the Washington University School of Medicine, and co-author of the study.

In Alzheimer’s patients, abnormal increases in neuronal activity are likely to further impair brain function, adds Holtzman.

As such, he says, “the implications of part of our study for current patients with Alzheimer’s disease are that good glucose control may prevent worsening of cognitive function in real time, on a daily basis in patients with high glucose and Alzheimer’s disease.”

—Mark McGraw

Reference

Macauley S, Stanley M, et al. Hyperglycemia modulates extracellular amyloid-β concentrations and neuronal activity in vivo. Journal of Clinical Investigation. 2015.