Diabetes May Speed Up Dementia

Type 2 diabetes and poor blood sugar may accelerate loss of brain size and function

/ Author:  / Reviewed by: Robert Carlson, M.D

(RxWiki News) As you grow old, your brain starts to get smaller and lose power. Certain diseases can make this decline in brain function even worse. It seems diabetes may be one of these diseases.

Pre-diabetes and type 2 diabetes may speed up the decline in brain size and mental function associated with aging.

"Work with your doctor to protect your brain from diabetes."

It is normal to lose brain volume as you age. However, elderly people with high blood sugar - such as those with diabetes and pre-diabetes - appear to lose more brain volume than those without diabetes over a two year period, according to a recent study led by Katherine Samaras, Ph.D., of the Garvan Institute of Medical Research, and colleagues.

The frontal lobe is a part of the brain associated with decision-making, long-term memory, and emotional control. When the frontal lobe gets smaller, it can have a heavy effect on a person's mental function and quality of life.

Dr. Samaras and colleagues found that people with out-of-control blood sugar levels lost nearly two and a half times more brain volume than those with stable blood sugar levels.

They concluded that a person's blood sugar after two years can act as a strong predictor of a loss in brain size.

"These findings highlight the importance of prevention of diabetes," says Dr. Samaras.

"They also emphasize that, in the elderly, clinicians and allied health professionals need to understand that the complexity of diabetes care needs to accommodate expected declines in cognitive function."

While the study found a relationship between blood sugar levels and brain size, it does not explain how diabetes causes the loss in brain size and function. More research is needed to understand the role of diabetes in declining brain function.

"We need to understand why these changes in cognition and brain size occur," explains Dr. Samaras.

"Is it due merely to higher blood sugars? Is the brain subject to the toxic effects of glucose, just as peripheral nerves are? Tow what extent do other factors associated with diabetes also contribute to the decline in brain size and function, for example inflammation or blood fat levels," she asks.

"We also need to learn how we can prevent or deter the negative effects of diabetes on the brain," she adds.

For their study, the researchers looked at MRI scans of 312 Australians between 70 and 90 years old. None of the participants had dementia (loss of brain function) at the beginning of the study.

The participants were separated into four groups. The first group had normal, stable blood sugar levels. The second had stable pre-diabetes (higher than normal blood sugar levels, but not quite high enough to be called diabetes. The third had blood sugar levels that had gotten worse. The fourth group consisted of those who already had type 2 diabetes.

While the normal group lost an average of 18.4 cubic centimeters of brain volume over two years, those with stable pre-diabetes lost an average of 26.6 cubic centimeters - about 1.4 times more brain volume loss than those in the normal group. Both those with worsening blood sugar and those with diabetes lost 2.3 times more brain volume than those with normal blood sugar.

This research was presented at the joint International Congress of Endocrinology and European Congress of Endocrinology in Florence, Italy. As such, the study still needs to be reviewed by a body of peers.

Reviewed by: 
Review Date: 
May 8, 2012
Last Updated:
May 11, 2012