New research into the causes of Alzheimer’s disease is showing an intriguing new direction in formal treatment — one that might lead to successful treatment in the early stages of the disease. Two new studies from The Warren Alpert Medical School at Brown University identified diminished insulin availability as well as insulin resistance in the brain as a possible trigger for the brain deterioration, loss of cognitive function and buildup of plaques (protein fragments between brain neurons) and tangles (twisted fibers inside brain cells) that characterize Alzheimer’s. “We’ve found Alzheimer’s to be a form of diabetes,” I was told by Suzanne de la Monte, MD, MPH, senior researcher on the study, when I called to ask what this might mean.
In one study, researchers depleted insulin and at the same time produced insulin resistance in the brains of rats by injecting Streptozotocin (or STZ), a compound known to destroy insulin-producing cells in the pancreas. As they had hypothesized, the result was overall brain deterioration in the rats. Even more exciting: In a subsequent study using the same rats — who now exhibited symptoms resembling Alzheimer’s — researchers then reversed the insulin resistance in their brains by administering three classes of drugs called PPAR (peroxisome-proliferator activated receptor) agonists. (The agonists are drugs but the receptors are normally present in the brain.) Following this treatment, the Alzheimer’s-like brain abnormalities and degeneration that the rats had displayed were either reduced or nearly disappeared. Of the three classes of agonists used, one — PPAR delta — had the most benefit in preserving brain tissues and improving learning memory. PPAR alpha was less effective. Another PPAR agonist — PPAR gamma — that is already being prescribed as a treatment in type 2 diabetes to modulate insulin response, was least effective. This research has yet to be applied to humans, noted Dr. de la Monte. But she is definitely thinking ahead. “We’ve seen the incidence of both type 2 diabetes and Alzheimer’s disease grow in epidemic proportions, and researchers now recognize both the overlap of the two conditions and the increased risk for developing Alzheimer’s in patients with type 2 diabetes.” But while Dr. de la Monte refers to this as a separate process, a “type 3” diabetes or “diabetes of the brain,” Daily Health News consulting medical editor Andrew L. Rubman, ND, observes that the underlying collapse of the regulatory systems that are behind both type 1 and type 2 diabetes is also present in “brain diabetes.”
Obviously, a great deal of research needs to be done before these findings lead to a solid connection between Alzheimer’s and diabetes, and even more until possible treatment is available. But, Dr. de la Monte shared her thoughts on how this information might be useful in the short term: “When we think about type 2 diabetes and how much it is mediated by lifestyle and environmental factors — and that we know the same is true for insulin resistance in the liver — you can’t help but wonder to what extent this is also true for insulin resistance in the brain, which our research showed often results in Alzheimer’s symptoms.” And, she concluded, when you start thinking like that, the next question is — “What are the specific lifestyle features that contribute to this? Now, you’re talking about prevention, which almost certainly would involve lifestyle choices.”
