Diabetes shrinks elderly brains more quickly

Diabetes accelerates the decline of brain size and mental capacity in elderly people with pre-diabetes and type 2 diabetes, according to research presented at the joint International Congress of Endocrinology/European Congress of Endocrinology in Florence, Italy.

Researchers from Garvan Institute of Medical Research in Australia found that elderly people with blood sugar levels in flux and those with type 2 diabetes lost almost two and a half times more brain volume than those without high blood sugar levels.

They noted that the brain's frontal lobe decreased in size the most over the study's two-year period. That part of the brain handles higher mental functions like decision making, emotional control, and long-term memory.

While some brain volume loss is a normal part of aging, the aging brain is vulnerable to worsening blood sugar levels even before type 2 diabetes is diagnosed.

The researchers used MRI to compared the brains of more than 300 people who participated in the study. Each participant was scanned at the beginning and end of the two-year period. All were Australians aged 70 to 90 years old and were free from dementia. 41 percent had pre-diabetes and 13 percent had type 2 diabetes at the beginning of the study.

At the end of the study, 102 people had normal, stable glucose levels and 120 people had stable pre-diabetes. About 57 people had worse glucose levels than at the start of the study. 33 people had type 2 diabetes from the start.

The normal group lost an average of 18.4 cm3 total brain volume over two years. The stable pre-diabetic group lost 1.4 times more brain volume than the normal group. The worsening glucose group and the type 2 diabetes group both lost about 2.3 times more brain volume than the normal group.

“These findings highlight the importance of prevention of diabetes,” said Katherine Samaras, associate professor at the Garvan Institute of Medical Research and lead researcher on the study. “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.”

Samaras emphasized the need for scientists to discover how to prevent or deter the negatives effects of diabetes on the brain.

Diabetes affects 285 million people, or about 6.4 percent of the population worldwide. About 344 million people also have pre-diabetes, a condition while mildly elevated blood sugar levels that gives them a 50 percent risk of developing type 2 diabetes over ten years.

Source: European Society of Endocrinology