Older Australians with type 2 diabetes may be more likely to experience cognitive decline as a result of the health condition, new research has shown.
A study published in the Journal of Diabetologica found people over the age of 55 living with type 2 diabetes are likely to experience a decline in verbal memory and fluency over five years. The research noted that previous studies have linked a decrease in brain volume with type 2 diabetes in older members of society and that it can also double the risk of dementia in older people.
Researchers from the University of Tasmania, Monash University and Murdoch Children’s Research Institute aimed to discover whether type 2 diabetes was associated with greater brain atrophy and cognitive decline and whether both were linked to each other. It was the first study that compared cognition and brain atrophy between people living with and without type 2 diabetes in the same study.
For the trial, 705 people aged between 55 and 90 were recruited as part of the Cognition and Diabetes in Older Tasmanians study. This included 348 people with type 2 diabetes and 357 without.
Each participant underwent brain MRIs that measured brain atrophy and neuropsychological measures that analysed cognitive function at three time points over a follow-up period of just under five years.
The results found a significant association between type 2 diabetes and a decline in verbal memory and verbal fluency. And, while people living with diabetes had greater brain atrophy at the beginning of the study, there was no difference in the rate of it between those with and without diabetes.
It was also found that the rate of brain atrophy didn’t directly impact the diabetes-cognition relationship. What researchers did find is for people without type 2 diabetes, verbal fluency slightly increase each year, while it decreased in those with the condition.
“Such accelerated cognitive decline may contribute to executive difficulties in everyday activities and health behaviours – such as medication compliance – which in turn may poorly influence future vascular health and cognitive decline, and possibly an earlier onset of dementia in those with type 2 diabetes,” the study’s authors said in a statement.
The researchers also said that despite their hypotheses and the results of previous studies, the rate of brain atrophy over the five-year study didn’t directly mediate associations between type 2 diabetes and cognitive decline.
“It is possible that the greater accrual of cerebrovascular disease than occurred in our study may be more likely to reveal whether there is such a relationship,” the authors added.
The study concluded that while type 2 diabetes is associated with a decline in verbal memory and fluency, the effect of diabetes on brain atrophy specifically may begin at an earlier point in life, such as midlife. Researchers came to this conclusion because there was evidence of greater brain atrophy in those with type 2 diabetes when the study began.
Researchers said both pharmacological and lifestyle interventions would need to commence sooner than old age to prevent brain atrophy in those with type 2 diabetes.