Sweet memories

Messier Claude

“We used to call type 2 diabetes ‘old age diabetes,’ but it’s now ‘every age diabetes.’”

– Claude Messier

A professor in the University of Ottawa’s School of Psychology, Messier studies the effects of glucose on memory. His research has led to tremendous changes in the field. During the mid-1990s, at a time when many researchers thought that diabetes and Alzheimer’s disease were unrelated, Messier wrote a review that explained how the former could indeed be a risk factor for the latter. Today, after further work by other scientists, it is widely accepted that insulin resistance—a hallmark of type 2 diabetes—can hasten the onset of Alzheimer’s disease.

Messier and his research team have found that both memory and the capacity to perform complex mental tasks are impaired in older people who are not yet diabetic, but who show early signs of the disease. But that doesn’t mean that type 2 diabetes is only an illness of the elderly, he cautions.

“We used to call type 2 diabetes ‘old age diabetes,’ but it’s now ‘every age diabetes,’” says Messier.

According to the Canadian Diabetes Association, more than nine million Canadians currently live with diabetes or prediabetes. With the growing prevalence of obesity and inactivity, diabetes is increasingly affecting young people. In fact, a report released earlier this year by the Centers for Disease Control and Prevention in the United States found that more than 20 percent of adolescents have diabetes or prediabetes, compared with nine percent a decade ago. Canadian research has also shown a similar increase among youth in Canada.

Unfortunately, as Messier and other researchers are discovering, being young offers no protection from the changes in intellectual functioning associated with type 2 diabetes. And those changes have a lot to do with the size of some parts of the brain. Imaging studies have shown that diabetes and its inherent high blood glucose level can lead to brain shrinkage. Even though researchers don’t fully understand the mechanisms behind that reduction—cell death has been suggested—one thing is certain: when it comes to the proper functioning of the brain, decreasing size matters. Particularly since diabetes-related shrinkage occurs in areas of the brain that control the ability to make memories, learn new things, make decisions and plan ahead.

In his latest research project, Messier is looking at glucose regulation and specific cognitive changes among young non-diabetics. So far, he has found that the brain can suffer from the effects of high glucose levels long before diabetes develops. But since those problems may be mild and even undetectable by people experiencing them, those who are at risk of developing diabetes may not make the necessary lifestyle changes to help prevent the disease. Those measures include healthy eating, being physically active and controlling one’s weight.

Messier admits it is difficult to convince people to change their eating and exercise habits decades before facing a diabetes diagnosis—our brains are not naturally inclined to take the long view. He, however, has seen first-hand the positive results of early and effective management of blood glucose levels. His uncle, Bernard Messier, a former director of the Department of Anatomy at Université de Montréal (and Messier’s “inspiration for doing research”), was diagnosed with diabe­tes in his forties. By carefully managing the condition, though, he has continued to maintain strong cognitive abilities into his late eighties.

In his early days as a researcher, Messier discovered a physiological paradox: consuming a high-glucose meal produced cognitive improvement, but only in people already struggling with insulin resistance. “Our bodies are not meant to sustain high glucose levels,” he says, “be it because of diabetes or eating snacks throughout the day.”

The key, says Messier, is for researchers to find a way to restore the brain’s sensitivity to insulin and to protect the brain from the vascular problems that accompany diabetes. The importance of such a dis­covery cannot be overstated: for the earlier in life people experience consistently high blood sugar levels, the earlier they may experience attendant damage to their brains.  

 

by Dana Yates

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