Obesity and Alzheimer’s
High Insulin Levels Linked to Alzheimer’s

By Daniel J. DeNoon , WebMD Medical News
Reviewed by Brunilda Nazario, MD

Aug. 8, 2005 — Today’s obesity epidemic may be tomorrow’s Alzheimer’s disease epidemic, a new study shows.

People with diabetes are at particularly high risk of Alzheimer’s disease. But now there’s strong evidence that people with high insulin levels — long before they get diabetes — already are on the road to Alzheimer’s disease.

As the body becomes more and more overweight, it becomes more and more resistant to the blood-sugar-lowering effects of insulin. To counter this insulin resistance, the body keeps making more insulin. If it continues, this escalating cycle of insulin resistance and insulin production end in type 2 diabetes.

Insulin Triggers Amyloid Buildup
High insulin levels are known to cause blood vessels to become inflamed. Inflamed tissues send off chemical warning signals. These warning signals set off an avalanche of tissue-damaging effects.

But insulin doesn’t just cause inflammation in the lower body. It also causes inflammation in the brain, find University of Washington researcher Suzanne Craft, PhD, and colleagues.

One dangerous effect of this insulin-caused brain inflammation is increased brain levels of beta-amyloid. Beta-amyloid is the twisted protein that’s the main ingredient in the sticky plaques that clog the brains of people with Alzheimer’s disease.

“What was striking was the magnitude of the effect,” Craft tells WebMD. “Inflammation can be a result of amyloid elevations but can also create an environment in which amyloid is made more readily. Inflammation can be both the result and cause of amyloid production.”

Brave Volunteers
Craft’s research team signed up 16 very brave volunteers. These men and women, ranging in age from 55 to 81, let research doctors give them two-hour infusions of both insulin and sugar. This kept their blood sugar at normal levels while creating the same kind of high insulin levels seen in people with insulin resistance. The volunteers then let the researchers give them a spinal tap so they could analyze their spinal fluid.

Just this brief rise in insulin levels had what Craft calls “striking” effects: It set off inflammation in the brain.

The spinal fluid had increased levels of a compound called F2-isoprostane. Alzheimer’s patients have unusually high brain levels of F2-isoprostane.
Brain levels of beta-amyloid increased.

Except for the spinal tap, many Americans already are undergoing the same experiment as the study volunteers did. And they are doing it for a lot longer than two hours.

Because they are overweight and inactive — and because they may have genetic risk factors — many people have high insulin levels. It’s not good for their hearts. And it’s not good for their brains, says Samuel Gandy, MD, PhD. Gandy, chairman of the Alzheimer’s Association’s medical and scientific advisory committee, is director of the Farber neuroscience institute at Thomas Jefferson University, Philadelphia.

“I think this reinforces the idea that it’s wise to maintain your brain,” Gandy tells WebMD. “Controlling blood sugar and body weight — all those things we know are good for your heart health are also really good at preventing Alzheimer’s disease. So there are more and more reasons not to be slouchy about getting these things under control.”

Craft and colleagues report their findings in the October issue of Archives of Neurology.

Health Dangers of Obesity – Some Facts

An estimated 300,000 deaths per year may be attributable to obesity.

Even moderate amounts of excess fat (10 to 20 pounds for a person of average height) increases the risk of death, particularly among adults aged 30 to 64 years, especially if this fat is stored as abdominal fat tissue.

Individuals who are obese (BMI > 30) have a 50 to 100% increased risk of premature death from all causes, compared to individuals with a healthy weight.

Heart disease is increased in persons who are overweight or obese (BMI > 25).

High blood pressure is twice as common in adults who are obese than in those who are at a healthy weight.

A weight gain of 11 to 18 pounds increases a person’s risk of developing type 2 diabetes to twice that of individuals who have not gained weight.

Overweight and obesity are associated with an increased risk for some types of cancer including endometrial, colon, gall bladder, prostate, kidney, and postmenopausal breast cancer.

Women gaining more than 20 pounds from age 18 to midlife double their risk of postmenopausal breast cancer, compared to women whose weight remains stable.

Watch your waistline measurements more than the pounds you want to lose.

Carrying fat around the stomach can quadruple the risk of diabetes and heart disease. Women with waists over 35ins and 40in-waists on men are classed as high risk. And these measurements rather than overall weight which experts believe are the best predicator of future health problems. Weight measurements are very important in predicting the risks of Type 2 diabetes and heart diseases among individuals who are clinically obese. Measuring your waist is a useful tool in making sure you remain healthy in the future.

Dr. Syverain and his team of experienced physicians can help you take small steps toward a healthier you. The important fact is knowing that weight management is a lifestyle choice that should not be a quick fix. You can live a great and healthy life, enjoy the meals you want- all with moderation.

We invite you to come visit us for a free consultation and get on track with the new and healthier you.