New research has found that, among older adults, type 2 diabetes could be tied to a decline in verbal memory and fluency over a span of five years.
According to Dr. Michele Callisaya, the lead researcher, and her colleagues from the University of Tasmania and Monash University in Australia, the study is the first to examine a reduction in both cognition and brain atrophy in patients with type 2 diabetes and without, in the same probe.
In prior studies, type 2 diabetes was linked to an increased risk of dementia in older adults. However, in contrast to past research, the new trial has shown a decrease in brain volume in older adults with type 2 diabetes and did not associate it with cognitive decline. Those with the condition had greater brain atrophy at the start of the study, compared to those without it.
For the new study, 705 participants aged 50-90 were recruited from the Cognition and Diabetes in Older Tasmanians (CDOT) trial. 348 of participants met the criteria for type 2 diabetes, while 357 did not. All participants, over a period of four years, underwent brain MRI and neuropsychological tests to measure cognitive domains and brain atrophy.
The results, which took into account age, sex, education, and vascular risk factors, demonstrated a strong correlation between type 2 diabetes and a decline in both verbal memory and fluency. In those without the condition, verbal fluency increased each year, whereas diabetic patients saw a decline.
“Such accelerated cognitive decline may contribute to executive difficulties in everyday activities and health behaviors — 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,” researchers stated.
“In older community-dwelling people, type 2 diabetes is associated with a decline in verbal memory and fluency over approximately 5 years, but the effect of diabetes on brain atrophy may begin earlier, for example in midlife, given the evidence of greater brain atrophy in people with T2D at the start of the study.”
“If this is the case, both pharmacological and lifestyle interventions to prevent brain atrophy in people with T2D may need to commence before older age.”
The findings were published in the journal Diabetologia.