Sugar can shrink your brain, ANU study finds

We all know sugar can rot your teeth, but new research from the Australian National University has shown it can rot your brain as well. According to Dr Nicolas Cherbuin, people whose blood sugar is at the high end of the normal range may be at risk of the brain shrinkage that occurs with ageing and diseases like dementia.

“Numerous studies have shown a link between type 2 diabetes and brain shrinkage and dementia, but we haven’t known much about whether people without diabetes with blood sugar on the high end of normal experience these same effects,” said Dr Cherbuin, an academic at the Centre for Research on Ageing, Health and Wellbeing in the ANU College of Medicine, Biology and Environment.

Cherbuin studied 249 people ranging in age from 60 to 64 whose blood sugar fell in the normal range. Participants had a brain scan at the start of the study and another four years later.

“Blood glucose levels are measured in millimoles per litre (mmol/L); a normal blood glucose level is considered to be between 4.0 and 6.1 mmol/L. Those with higher blood sugar levels within the normal range were more likely to have a loss of brain volume in the areas of the hippocampus and the amygdala - areas that are involved in memory and cognitive skills - than those with lower blood sugar levels,” Cherbuin said.

The results of the study were surprising: blood sugar at the higher end of the normal range accounted for 6 to 10% of brain shrinkage.

“These findings suggest that even for people who do not have diabetes, higher blood sugar levels could have an impact on brain health,” said Cherbuin. “More research is needed, but these findings may lead us to re-evaluate the concept of normal blood sugar levels and the definition of diabetes.”

Dr Cherbuin’s study was supported by the National Health and Medical Research Council.