Link Between Sugar and Alzheimer’s Strengthens By Dr. Mercola for Mercola
Alzheimer’s disease — for which conventional medicine believes there is no effective treatment or cure — currently affects an estimated 5.4 million Americans1 and prevalence is projected to triple by 2050.2,3 Within the next two decades, this severe and lethal form of dementia may affect as much as one-quarter of the U.S. population. Already, more than half a million Americans die from the disease each year, making it the third leading cause of death in the U.S., right behind heart disease and cancer.4,5
The good news is that lifestyle choices such as diet, exercise and sleep can have a significant impact on your risk. As previously noted by Dr. Richard Lipton6 of the Albert Einstein College of Medicine where they study healthy aging, lifestyle changes “look more promising than the drug studies so far.” As with health in general, your diet plays a crucial role. Processed foods tend to be nearly devoid of healthy fat while being excessive in refined sugars, and this combination appears to be at the heart of the problem.
High-Sugar Diet Significantly Raises Your Risk of Dementia
One of the most striking studies7 on carbohydrates and brain health revealed that high-carb diets increase your risk of dementia by a whopping 89 percent, while high-fat diets lower it by 44 percent. According to the authors, “A dietary pattern with relatively high caloric intake from carbohydrates and low caloric intake from fat and proteins may increase the risk of mild cognitive impairment or dementia in elderly persons.”
Studies also strongly suggest Alzheimer’s disease is intricately connected to insulin resistance;8 even mild elevation of blood sugar is associated with an elevated risk for dementia.9 Diabetes and heart disease10 are also known to elevate your risk, and both are rooted in insulin resistance.
This connection between high-sugar diets and Alzheimer’s was again highlighted in a longitudinal study published in the journal Diabetologia in January 2018.11 Nearly 5,190 individuals were followed over a decade, and the results showed that the higher an individual’s blood sugar, the faster their rate of cognitive decline.
Both Type 1 and Type 2 Diabetics Have Higher Risk for Alzheimer’s
The connection between sugar and Alzheimer’s was first broached in 2005, when the disease was tentatively dubbed “Type 3 diabetes.” At that time researchers discovered that your brain produces insulin necessary for the survival of your brain cells.12 A toxic protein called ADDL removes insulin receptors from nerve cells, thereby rendering those neurons insulin resistant, and as ADDLs accumulate, your memory begins to deteriorate.
Curiously, while low insulin levels in your body are associated with improved health, the opposite appears to be true when it comes to the insulin produced in your brain. Reduced brain insulin actually contributes to the degeneration of brain cells, and studies have found that people with lower levels of insulin and insulin receptors in their brain often have Alzheimer’s disease.
According to researchers,13 “These abnormalities do not correspond to Type 1 or Type 2 diabetes, but reflect a different and more complex disease process that originates in the central nervous system.”
In 2016, researchers at John’s Hopkins department of biology discovered that nerve growth factor, a protein found in your nervous system that is involved in the growth of neurons, also triggers insulin release in your pancreas.14 So there appears to be a rather complex relationship between body insulin, brain insulin and brain function, and we’ve probably only begun to tease out all of these connections.
Case in point, even Type 1 diabetics are at increased risk for Alzheimer’s, even though their bodies don’t produce insulin at all. Melissa Schilling, a professor at New York University, investigated this paradox in 2016. As reported by The Atlantic:15
“Schilling posits this happens because of the insulin-degrading enzyme, a product of insulin that breaks down both insulin and amyloid proteins in the brain — the same proteins that clump up and lead to Alzheimer’s disease. People who don’t have enough insulin, like those whose bodies’ ability to produce insulin has been tapped out by diabetes, aren’t going to make enough of this enzyme to break up those brain clumps.
Meanwhile, in people who use insulin to treat their diabetes and end up with a surplus of insulin, most of this enzyme gets used up breaking that insulin down, leaving not enough enzyme to address those amyloid brain clumps. According to Schilling, this can happen even in people who don’t have diabetes yet — who are in a state known as ‘prediabetes.’”
Sugar Damages Brain Structure and Function
Research16 published in 2013 showed that sugar and other carbohydrates can disrupt your brain function even if you’re not diabetic or have any signs of dementia. Here, short- and long-term glucose markers were evaluated in healthy, nondiabetic, nondemented seniors. Memory tests and brain imaging were also used to assess brain function and the actual structure of their hippocampus.