The connection between diabetes and Alzheimer’s

The deepening link between diabetes and Alzheimer’s raises a frightening possibility: with diabetes on the rise worldwide, will this also worsen the rising toll of Alzheimer’s?

New, powerful findings connecting the disorders were presented this month at an Alzheimer’s Association conference in Madrid attended by 5,000 researchers from around the world. The findings suggest that dementia be added to risks already associated with diabetes including heart disease, strokes, blindness, kidney failure and amputations.

Several large studies in the past have found that people with Type 2 diabetes were twice as likely to develop Alzheimer’s. Researchers suspect the cause was related to cardiovascular problems caused by diabetes which may in turn contribute to dementia by blocking blood flow to the brain or causing stroke. More recent findings indicate yet another connection: the build up of the destructive protein amyloid – in the brain in Alzheimer’s and the pancreas in Type 2 diabetes.

New studies have focused on the effects of high blood sugar levels in some people with diabetes. (Higher levels of blood sugar mean the disease issevere or not being properly treated or both.) Findings suggest that as blood sugar control worsens, the risk of Alzheimer’s climbs astronomically – and for people with full-blown diabetes as much as 83 per cent.

“It really shows there is a link between the two diseases,” Rachel Whitmer, an epidemiologist with Kaiser Permanente’s Division of Research in California told U.S. News and World Report. She and her colleagues followed nearly 23,000 diabetics, with an average age of 66, for about eight years. During that time, their blood sugar control was frequently monitored with a test called an A1c.

“And for all of us it {the findings}underlines how important it is to control your blood sugar,” says Whitmer.

Another similarity between the two conditions: cells in the brain that cannot properly handle insulin – a hallmark of diabetes – develop damage that looks exactly like the ravages of Alzheimer’s. In fact, the resemblance is so strong that some researchers are starting to call Alzheimer’s “Type 3 diabetes.”

People with borderline diabetes are also at greater risk for dementia. Researchers at Stockholm’s Karolinska Institute studied the medical exams of about 1,100 people who were free of both diabetes and Alzheimer’s over a period of nine years. Some developed what is called borderline diabetes, meaning their blood sugar levels started to climb above normal but not quite to diabetic levels. These people had a risk of developing dementia that was nearly 70 percent higher than people without elevated blood sugar levels.

Worldwide diabetes is on the rise, increasing to 230 million cases from 30 million in the past twenty years. Alzheimer’s affects on in 10 people over 65, and nearly half of those over 85. Currently, about 4.5 million Americans have it, according to the Alzheimer’s Association. And this number is expected to grow, possibly reaching 11.3 million to 16 million by 2050.

And these projections do not include a possible increase from diabetes.

“Alzheimer’s is going to swamp the health-care system,” Dr. John Morris, a neurology professor at Washington University and advisor to the Alzheimer’s Society, was quoted in The New York Times.

“A connection between Alzheimer’s and diabetes has major public health implications,” said Ronald Petersen, M.D., Ph.D., vice chair of the Alzheimer’s Association’s Medical & Scientific Advisory Council. “The number of people with Alzheimer’s, and the number that will soon get it, is rising dramatically as the baby boomers turn 60, which is approaching the age of highest risk. Will this growth be redoubled by the rising tide of obesity and diabetes?”

But understanding the link between diabetes and Alzheimer’s may also shed light on more effective treatments. The same drugs and other treatment strategies such as change in diet and exercise that successfully treat diabetes, for instance, may prove useful with Alzheimer’s.

“It’s preliminary, but it’s also truly exciting,” said neurologist Ronald Petersen, director of the Mayo Clinic’s Alzheimer’s Disease Research Center in Minnesota. “We’ve been kind of stuck developing new Alzheimer’s therapies, and this gives us a whole new avenue to try.”

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