Does diabetes cause Alzheimer's?
Why connection could create cure or lead to public health problem

Does having diabetes put one at greater risk for Alzheimer's disease? Several research studies over the past decade are showing a link between the two diseases.

For some scientists the link is so strong that they believe Alzheimer's may actually be a type of diabetes.

"Several studies have shown that people with type 2 diabetes are more likely to develop Alzheimer's than someone who doesn't have diabetes," said Dr. Patience Reading, a neurologist with The Austin Diagnostic Clinic. "Understanding all of the reasons for this connection is the next step."

What worries some doctors is that if the correlation between the two diseases is as strong as research indicates, the number of people who develop Alzheimer's could skyrocket in the future. More than 14 million Americans have diabetes, and another 6 million are unaware they have the disease.

With cases of type 2 diabetes rising -- an increase that is being attributed to a rise in obesity -- the number of people who develop Alzheimer's over the next few decades may be even greater than anticipated.

"It could be the `perfect storm,'" said Reading. "Approximately 4.5 million Americans have Alzheimer's disease, and that number is expected to be three times as high by 2050 due to how the U.S. population is aging. And that doesn't even take into account the possible diabetes rise. If you consider the cost of caring for a person with Alzheimer's, a large public health problem could be on the horizon."

The Alzheimer's Foundation of America estimates that annual costs of caring for one patient with Alzheimer's ranges from $18,500 to more than $36,000. On average, a patient with Alzheimer's lives eight to 10 years after being diagnosed with the disease.

What is the connection between the two diseases? Type 2 diabetes, the most common form, occurs when the body can't properly use the hormone insulin. While the body uses insulin to control blood sugar use and levels, scientists have found that the brain also produces insulin to feed cells that help people learn and remember. Too much insulin in the body may create a chemical imbalance, triggering Alzheimer's, some researchers say.

"Another explanation that is being researched is that the buildup of blood sugar caused by uncontrolled diabetes results in inflammation that damages brain cells," said Reading.

"An additional possibility is that because diabetes raises the risk of heart disease and stroke, damaged blood vessels in the brain may lead to Alzheimer's."

If the mystery surrounding the link between diabetes and Alzheimer's could be unraveled, there is the possibility that doctors could use already developed diabetes drugs to treat or prevent Alzheimer's.

In fact, one recent Swedish study has already shown that a certain class of diabetes medications may help people with diabetes from developing Alzheimer's.

Does taking steps to prevent diabetes help prevent Alzheimer's? "There's no definitive answer yet," said Reading. "But it can't hurt."

Another recent study reported that even people who had "borderline" diabetes were 70 percent more likely than people who had normal blood sugar to develop Alzheimer's. Type 2 diabetes prevention guidelines include losing weight, exercising regularly and eating a low-fat, well-rounded diet with lots of fruits and vegetables.

"Alzheimer's is a disease that robs people of the ability to lead their everyday lives and strips them of their most precious memories," said Reading. "The research into the link between Alzheimer's and diabetes offers hope for a cure."