cutaway of blood vessel shows arteriosclerosis

Scientists don’t have all the answers when it comes to understanding the link between diabetes and cognitive decline, especially when it comes to biomarkers for Alzheimer’s disease. 

A new study examined how small vessel disease, or SVD, and amyloid proteins can contribute to lower cognitive function in older adults with type 2 diabetes. SVD is the most common vascular disease that’s progressive with age. In fact, it’s quite common to see SVD on brain scans in people over the age of 80.

Insights from the research could introduce a multifaceted approach to diagnose, prevent and treat cognitive decline in older adults who have type 2 diabetes. 

The association between Alzheimer’s disease and diabetes, as well as the link between amyloid pathology and cognitive functioning, both are controversial, with inconclusive results in previous research. Some evidence shows a link between diabetes and a higher risk for Alzheimer’s disease, but some studies haven’t shown the association. And other studies find a lower pathology for Alzheimer’s disease in people with diabetes.

Likewise, some research shows that higher amyloid is linked to lower cognitive function, but others don’t show that association. There’s not a lot of information on the effect of amyloid buildup on cognition in people who have diabetes. But researchers do know that higher levels of beta-amyloid tend to occur with amyloid plaque buildup, which is indicative of Alzheimer’s disease. 

The researchers evaluated 47 participants from Israel who were aged more than 65 years and who had both amyloid-PET and MRI scans between 2013 and 2019. 

Higher amyloid and white matter hyperintensities, a measure of SVD, were independently associated with lower cognitive functioning after adjusting for glycemic control, according to the investigators. The findings indicate that multiple factors may have contributed to cognitive decline independently in the older adults studied.

Several blood tests have been studied and are emerging to help clinicians obtain a clear view of biomarker levels when diagnosing Alzheimer’s disease and related dementias.