Alzheimer's disease is a chronic disease frequently associated with age. It is the most common dementing illness and affects 50% of those who reach age 85. Type II diabetes, insulin resistance and the Metabolic Syndrome are all considered risk factors for this disorder because they double or triple the chances of developing it and may also accelerate disease progression. Based on this observation, it is reasonable to conclude that abnormalities of either blood sugar or insulin metabolism play a pivotal role. If that is true, then it is likely that refined and other rapidly digested carbohydrates are important factors as well.
The characteristic brain tissue findings associated with Alzheimer's disease, senile plaques and neurofibrillary tangles , were identified by Alois Alzheimer about 100 years ago. The 1990s were called the "Decade of the Brain" and with this designation research on Alzheimer's disease was put in the cross hairs of neurological investigators. While this helped, what really was instrumental in facilitating an improved understanding of what caused the disease was the recognition that aberrations of glucose and insulin metabolism were associated with increased incidence.
Among the vanguard of scientists pursuing this approach is Dr. Suzanne Craft at the University of Washington. She has documented numerous abnormalities of glucose and insulin metabolism in Alzheimer's disease and has observed associations between these metabolic changes and the physiology of the beta-amyloid peptide found in the senile plaques that accumulate in the brains of afflicted patients. Additional investigators pursuing this lead have found aberrations in the insulin signaling pathway in the brain, while other neuroscientists have identified a link between the degradation of beta-amyloid and IDE (Insulin Degrading Enzyme-the enzyme responsible for recycling the hormone insulin). When researchers inject a compound into the brains of mice that blocks the insulin receptor in the brain, or separately blocks the insulin signaling pathway, the animals develop plaque-like deposits and become demented. Doctors from Brown University Medical School have coined the phrase "Type III Diabetes" to refer to the inability of the brain to properly use glucose in Alzheimer patients, akin to what happens in the bodies of diabetics.
To evaluate whether such findings have clinical merit, Dr. Craft conducted a study in patients suffering from Alzheimer's disease. There are pharmaceutical compounds on the market that are able to improve the body's sensitivity to insulin. She asked the question, if insulin resistance (the metabolic abnormality linked with diabetes and the Metabolic Syndrome) truly does play a seminal role in this form of dementia, then a drug that is able to improve insulin sensitivity should be a beneficial treatment. That is exactly what she found! Such observations serve to open the door for new pharmaceutical approaches.
The most exciting news is that factors other than drugs can improve insulin sensitivity. They are diet and lifestyle choices including good nutrition, weight maintenance and exercise-all easily within our purview. The new book Good Calories, Bad Calories by Gary Taubes provides novel nutritional recommendations to help in this regard.
Just remember, the time to get started on such a brain-healthy program is now.