New research suggests that a decreased level of an enzyme that breaks down insulin -- insulin-degrading enzyme (IDE) -- in brain tissue is the missing link between the two disorders, according to Dr. Greg M. Cole’s research at the University of California, Los Angeles.

Moreover, since insulin's action in the brain increase IDE levels, it may be possible to prevent or even reverse Alzheimer's disease by boosting insulin activity.

Cole's group found in lab-dish experiments with brain neurons that insulin significantly increased IDE levels.

Comparing brain specimens obtained from normal patients and those with Alzheimer's disease, IDE was decreased in the Alzheimer's tissue, the researchers report the Journal of Neuroscience.

And in mice bred to develop a condition similar to Alzheimer's disease, a diet high in safflower oil led to significantly reduced levels of IDE and more of the amyloid beta plaques associated with the disease.

There are a number of approaches that may increase IDE levels and thus reduce amyloid beta in the brain, Cole noted. For example, the anti-diabetes drug Avandia "an agent used to treat insulin resistance, is currently being tested in a clinical trial to see if it can help patients with Alzheimer's disease," he said.

But even lifestyle changes -- increasing exercise, lowering saturated fats in the diet, and increasing dietary fish oil, which is rich in omega-3 polyunsaturated fatty acids -- can modify insulin's effects and perhaps "increase the degradation and clearance of amyloid beta," Cole concluded.

Source: Diabetes In Control.com: Journal of Neuroscience, December 8, 2004.