Concordia researchers identify key marker linking coronary artery disease to cognitive decline
Individuals with coronary artery disease (CAD) — a constricting or blocking of blood vessels feeding the heart — face increased risks of strokes, cognitive impairment and dementia. However, the link between CAD and cognitive function is not fully understood.
A new study led by Concordia researchers looks at how the disease affects the brain’s white matter, the network of nerve fibers that connects different regions of the brains and is critical to transmitting information efficiently.
The study, published in the journal Journal of Neuroscience, applied a novel multivariate approach using 12 separate metrics. The researchers compared test results and MRI scans of 43 patients with CAD to those of 36 healthy individuals. All participants were over age 50.
The researchers found that individuals with CAD had widespread structural changes in their white matter compared to their healthy counterparts. The changes were particularly noticeable in the parts of the brain fed by the middle cerebral (MCA) and anterior cerebral arteries. Both regions are key for cognitive and motor functions.
“This makes sense because those regions, especially the MCA territory, are most prone to strokes,” says PhD candidate Zacharie Potvin-Jutras, the study’s lead author. “We made sure that there was no history of strokes in our CAD cohort.
“Our goal is to examine conditions at the onset of a heart disease, before there has been any significant impact on the brain,” he says.
Small measurements provide a bigger picture
The multivariate approach of bundling individual white matter metrics into one overarching metric provides advantages over past univariate studies. It allows the researchers to simplify complex aspects of brain health into a single metric that can be compared to the same metric in healthy controls. While individual metric variations between CAD patients and healthy controls may be very small, when seen together, they can provide significant indicators of early stages of cognitive impairment.
“The metrics are often overlapping, meaning they measure things that are related to each other,” says corresponding author Claudine Gauthier, an associate professor in the Department of Physics. “Having one single metric that captures many aspects of brain health allows us to identify differences between patients and controls that reflect a complex combination of changes in a single analysis. Then we can unpack it and see which aspects of white matter health drove the difference more than the others.”
The researchers found that the changes were mainly linked to reduced myelin content — the fatty coating that insulates nerve fibers and allows signals to travel quickly through the brain. Myelin loss can slow communication between brain cells and is often an early sign of cognitive aging.
Interestingly, participants with higher measures of myelin integrity (specifically, in a marker called R1) performed better on tests of processing speed, a key aspect of thinking and attention. However, no significant differences were observed between groups in overall cognitive scores, suggesting that brain changes may precede noticeable symptoms.
“This study adds mechanistic insight into our understanding of how CAD affects white matter health,” says Gauthier. “Now that we know that myelin content is a good biomarker for coronary heart disease, the next step is to focus on potential interventions. If we have a preventive lifestyle intervention, we can optimize the intensity to improve myelin health and maintain cognitive function.”
The Canadian Institutes of Health Research, the Heart and Stroke Foundation of Canada and Brain Canada supported this research.
Read the cited paper: “Multivariate White Matter Microstructure Alterations in Older Adults with Coronary Artery Disease”
