New link between diabetes and Alzheimer's uncovered

Providing further evidence that diabetes can affect memory, researchers have uncovered a unique connection between diabetes and Alzheimer's disease.

Elevated glucose in the blood can rapidly increase levels of amyloid beta, a key component of brain plaques in Alzheimer's patients, the study conducted in mice showed.

The build-up of plaques is thought to be an early driver of the complex set of changes that Alzheimer's causes in the brain.

"Our results suggest that diabetes, or other conditions that make it hard to control blood sugar levels, can have harmful effects on brain function and exacerbate neurological conditions such as Alzheimer's disease," said lead author Shannon Macauley, postdoctoral research scholar at Washington University's School of Medicine.

"The link we have discovered could lead us to future treatment targets that reduce these effects," Macauley added.

People with diabetes cannot control the levels of glucose in their blood. Many patients rely on insulin or other medications to keep blood sugar levels in check. It especially spikes after meals.

To understand how elevated blood sugar might affect Alzheimer's disease risk, the researchers infused glucose into the bloodstreams of mice bred to develop an Alzheimer's-like condition.

In young mice without amyloid plaques in their brains, doubling glucose levels in the blood increased amyloid beta levels in the brain by 20 percent.

When the scientists repeated the experiment in older mice that already had developed brain plaques, amyloid beta levels rose by 40 percent.

Looking more closely, the researchers showed that spikes in blood glucose increased the activity of neurons in the brain that in turn promoted production of amyloid beta.

The research was published in The Journal of Clinical Investigation.