Brain Loss Linked to High Glycemic Eating

Several decades ago, researchers in food sciences and diabetes began exploring the effects of various foods on blood sugar and future risk for developing diabetes, a disease now affecting close to 26 million Americans that has been associated with a two-fold increased risk for the development of Alzheimer’s disease. Researchers at the University of Toronto, led by Dr. David J. A. Jenkins, realized that it was important to consider how rapidly and how high blood sugar would rise following the consumption of a particular food. They surmised that glycation, brought on by blood sugar, would be enhanced the longer the blood sugar remained elevated. So well beyond the notion that a particular food would
cause a spike in the blood sugar, the longer the blood sugar remained elevated, the greater the long-term damage. These scientists then developed a ranking system that has allowed us to look at foods in a new and very meaningful way: the glycemic index. The glycemic index not only provides important information as to how high blood sugar will rise but, perhaps more importantly, reveals how long the blood sugar will remain elevated.
The longer the blood sugar remains high, the greater the chance that sugar will bind to protein. And this process, glycation, is what greatly enhances both inflammation and the production of free radicals. And keep in mind that inflammation and free radical production directly damage our most vital tissues and organs.
Doctors now routinely evaluate a marker of glycation as part of a general laboratory assessment. The test most commonly used is called hemoglobin A1c or, more commonly, A1c. As the name implies, this test is a marker of glycation of the protein hemoglobin. Healthcare practitioners use the A1c test to determine a person’s average blood sugar over a three- to four-month period. The more the blood sugar levels remain elevated, the higher the A1c. But beyond simply as a marker of average blood sugar, the A1c test has far more important implications. This test provides valuable information about the glycation of proteins and thus gives insight into both the degree of inflammation as well as the activity of dangerous free radicals.
Percentage of annual brain loss
Figure 1. Percentage of annual brain loss compared to A1c Adapted from: Neurology 79, no.10 (2012): 1019-1026
A1c levels 4.4-5.2   ------Brain loss 0-.2
                  5.3-5.5----------------------.250-.375                               
                  5.6-5.8----------------------.375
                  5.9-9.0----------------------.375-.5
Now that you understand how glycation is so damaging to the brain as well as how the process can be measured, it shouldn’t surprise you to learn that there is a direct correlation between glycation, as measured by the A1c test, and actual damage to the brain. In a recent study published by the prestigious medical journal Neurology, researchers checked the blood A1c test in 201 nondiabetic adults with normal brain function and measured the actual size of the participants’ brains using MRI scans. After six years, the brain scans were repeated. What the researchers found was astounding: As you see in the graphic, there was a direct and powerful relation between the original A1c, a marker of glycation, and the degree of brain atrophy or shrinkage.
The most striking finding was that the A1c level was the most important predictor of brain shrinkage, far more powerful than other variables like alcohol intake, triglyceride level, or cholesterol level. And the empowering take-home message is that the degree of glycation, as measured by the A1c test and relates to the rate at which the brain shrinks, is directly related to food choices. Eating foods with a lower glycemic index will reduce glycation and preserve the brain.

pg3-4 Dr Perlmutter's Guide to Glymcemic Index
About the Author
David Perlmutter, M.D., is a practicing board-certified neurologist and Fellow of the American College of Nutrition.
He is the author of the #1 New York Times bestseller Grain Brain and lectures to medical doctors and healthcare providers worldwide.