Insulin Resistance and Alzheimer's Risk: A Two-Way Street

Health Writer

The link between diabetes and Alzheimer’s disease has been examined in epidemiological studies, which confirm that diabetes increases a person’s risk of developing ** Alzheimer’s disease**(AD). A new study sheds light on further links between Alzheimer’s disease and insulin resistance and high-blood sugar levels, and suggests that AD can raise the risk of developing diabetes.

Quick review of insulin resistance and diabetes

In the face of obesity or other circumstances like smoking, sleep apnea, use of steroids, and use of certain medications, your body may start to use insulin ineffectively. That results in glucose in the blood not being well-utilized by cells, and your pancreas is forced to work overtime to put out more insulin until it fatigues and fails. Thus, insulin resistance entrenches and high blood sugar levels persist. Insulin resistance can impact your heart, and will likely lead to prediabetes and, likely, full diabetes. As mentioned above, the damage to blood vessels caused by diabetes may raise the risk of an individual developing Alzheimer’s disease.

The study

In a study published in the journal Alzheimer’s and Dementia, researchers at the Icahn School of Medicine at Mount Sinai in New York found that the reverse of that relationship between Alzheimer's and diabetes may hold true, as well. Alzheimer's disease may set up a metabolic situation that encourages the development of insulin resistance in the brain. The study also revealed that when this process does occur, certain amino acids develop, and these could act as a biomarker of this impaired brain signaling link to insulin resistance risk. That could lead to a new test that identifies or measures these amino acid biomarkers, allowing doctors to intercept the insulin resistance.

The study is part of ongoing National Institutes of Health-funded research intended to examine the link between Alzheimer’s disease and diabetes. It’s also the first study that shows that mice with AD have insulin resistance in the brain’s hypothalamus, the area of the brain responsible for regulating metabolism of various nutrients like fatty acids, glucose, and amino acids in tissues including muscle, the liver, and fat tissue. Mice with AD showed elevated levels of BCAA (branched chain amino acids) in the blood.

A prior study showed that brain insulin signaling helps to regulate BCAA levels in the blood. The conclusion from the two studies is that BCAAs can be used as a biomarker for this AD link to insulin resistance risk, so the next step is to test this theory in humans.

The study's findings indicate that therapies need to be implemented to reduce the risk of prediabetes and diabetes because they can raise the risk of AD, and therapies need to be initiated to lower the risk of an AD patient developing insulin resistance.

Final comments

The researchers feel that this study is a turning point in understanding the relationship between Alzheimer’s disease, diabetes, and insulin resistance. It’s been recognized for some time that one reason it's important to limit and reverse diabetes is to reduce the associated risk of a patient developing Alzheimer’s disease. Now clinicians need to recognize that patients who develop AD may also be at risk of insulin resistance in the brain.

Lifestyle changes help AD and diabetes

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Amy Hendel, also known as The HealthGal, is a Physician Assistant, nutritionist and fitness expert. As a health media personality, she's been reporting and blogging on lifestyle issues and health news for over 20 years. Author of The 4 Habits of Healthy Families, her website offers daily health reports, links to her blogs, and a library of lifestyle video segments.