When you have type 2 diabetes, you probably cringe when you read news reports saying that having diabetes increases your risk of Alzheimer’s disease. Some people even call Alzheimer’s “type 3 diabetes.”
But now comes a comforting report saying that diabetes, including insulin resistance and an early form of diabetes we call glucose intolerance (also called prediabetes), do not seem to increase the pathological features found in Alzheimer’s. This means people with diabetes did not have any more amyloid-beta plaque in their brain than people without diabetes.
Not having plaque does not ensure that you will not develop dementia, and having plaque does not ensure that you will. Some people have a lot of plaque and never get dementia. But the two are related. In general, more plaque increases your risk.
This study did not, unfortunately, say there’s no link between diabetes and Alzheimer’s disease. Previous studies have shown that people with diabetes do have increased risk. But risk is not the same as disease. And risk markers are not always causative.
A Medscape commentary suggested that it’s a combination of pathological conditions, including Alzheimer’s, strokes, and atherosclerosis that results in dementia.
It may be that the increased risk doesn’t come from more plaque but from something else. Some people think that the problem is insulin resistance in the brain, and clinical trials of nasal insulin, which gets into the brain, will be recruiting in 30 cities starting this fall. A previous study with fewer patients did show some positive results.
The new study showing that diabetes doesn’t seem to cause increased plaque should stimulate more research to find out why the two diseases are related. Once we know the cause, we can seek the cure.
In the meantime, the best way to avoid Alzheimer’s is similar to the best way to control diabetes: Stay active, keep challenging your brain, and eat a healthy diet, where I define a healthy diet as one emphasizing real foods and avoiding processed foods. A low-carb diet works best for me, but some people do well on a low-fat diet or just a low-food diet.