High Insulin Levels Can Cause Alzheimer’s

Research published in April 2016 shows that high insulin levels can cause Alzheimer’s. Alzheimer’s disease is more common in diabetics. But until recently nobody knew why there would be this association. Finally new research from New York University (NYU) has shed light on this puzzle. It seems like the key is an enzyme that breaks down insulin, called insulin-degrading enzyme (IDE). Melissa Schilling (no relation to me), an innovation professor at NYU has discovered the metabolic pathway between diabetes and Alzheimer’s disease. This finding has enormous implications regarding the prevention of Alzheimer’s, as I will discuss below. Here is a link to the original paper.

Background information about Alzheimer’s

Alzheimer’s disease affects about 5.2 million Americans and 44 million people worldwide. Above all, there is a progressive loss of cognitive functioning over a long period of time due to senile plaques in the cerebral cortex and the subcortical areas of the brain. These senile plaques consist of amyloid-beta substance and neurofibrillary tangles. This protein material is like glue, which prevents the neurons from working properly and certainly causes memory loss and the confusion, which is so typical for Alzheimer’s patients. Normally amyloid-beta is in solution and prevents lipoproteins in the brain from oxidizing. But when the insulin-degrading enzyme is busy breaking down high levels of insulin, these processes overload this enzyme system. Amyloid-beta experiences supersaturation, as the body does not eliminate it at a normal speed. Consequently, this leads to the glue-like deposits of amyloid-beta in Alzheimer’s brains.

A 2004 estimate for the direct cost of Alzheimer’s disease to the US amounted to  $214 billion. By 2050 this could go up to $1.5 trillion, if there will be no cure Alzheimer’s.

High insulin levels can cause Alzheimer’s, but other mechanisms too

Professor Schilling found in her research that there are four main malfunctions that can lead to high amyloid-beta in the brain of Alzheimer’s patients.

1. First, with diabetes type1, when the patient does not receive enough insulin, the insulin-degrading enzyme in the brain is not working hard enough. This results in inadequate removal of amyloid-beta from the brain and neurofibrillary tangles of amyloid-beta accumulate.
2. Second, IDE requires zinc as a co-factor to work properly in breaking down amyloid-beta. Zinc deficiency is quite common, particularly in older people. In this case insulin levels are normal, but the removal of amyloid-beta from the brain is inadequate, as IDE function has become lower.
3. Furthermore, in early type 2 diabetes there are high insulin levels and there is a competitive inhibition of the elimination of insulin and amylin-beta. This is probably the most common form of getting Alzheimer’s disease.
4. Finally, excess production of an amyloidogenic protein can lead to an overabundance of amylin-beta, which overwhelms the insulin-degrading enzyme.

What treatment options are there for Alzheimer’s disease?

These four mechanisms from above have several implications as follows.

1. If a type 1 diabetic patient is insulin deficient, intranasal insulin would be beneficial.
2. If the patient has type 2 diabetes, intranasal insulin or insulin by injection would be the wrong approach. As stated earlier, there is the competitive inhibition of the elimination of insulin and amylin-beta. It is the insulin-degrading enzyme, which is the limiting factor. This involves simple dietary changes where the patient cuts out sugar and limits starchy foods in the diet. This normalizes insulin levels and the IDE function returns to normal.
3. Alzheimer’s patients and patients with mild cognitive dysfunction should be tested with glucose tolerance tests (GTT). It the test is abnormal, a knowledgeable dietician should be consulted.
4. Obesity is strongly associated with hyperinsulinemia and diabetes. Again frequent GTT should be done followed by dietary intervention when abnormal.
5. Professor Melissa Schilling stated that 86 million Americans are pre-diabetic, but they have no symptoms. Only glucose tolerance testing can diagnose that condition. This will prevent a lot of cases of diabetes and Alzheimer’s disease.
6. Large parts of the population have no knowledge of the glycemic index of carbohydrates. In order to limit glucose overload and excessive insulin production there is a need for educational nutritional programs. This will be a powerful tool in Alzheimer’s disease prevention.

High Insulin Levels Can Cause Alzheimer’s

Conclusion

It has been general knowledge for some time that diabetics have a higher rate of Alzheimer’s disease. People have known Alzheimer’s as “Diabetes of the brain” or “Type 3 Diabetes”. This new research has shed some light on the connection of elevated insulin to Alzheimer’s disease. It was news to me that there is a competitive inhibition of the elimination of insulin and amylin-beta via the insulin-degrading enzyme. It boils down to recognizing that sugar overconsumption causes Alzheimer’s disease. If you want to keep your brain power until a ripe old age, you better eliminate a lot of sugar and adopt a healthy Mediterranean diet.