People who are at higher risk of developing cardiovascular disease are also more likely to experience cognitive decline as they age, including signs of Alzheimer’s disease, according to a study published this week in the Journal of the American College of Cardiology.
The study’s findings are the latest to underscore the important connection between heart health and brain health.
“In the absence of effective treatments for dementia, we need to monitor and control cardiovascular risk burden as a way to maintain patient’s cognitive health as they age,” says Weili Xu, the study’s senior author and an epidemiologist at the Medical University in Tianjin, China, in a released statement.
Globally, 50 million people are believed to have Alzheimer’s disease or a related dementia, including 5.7 million in the United States. Those numbers are expected to rapidly increase in coming years, doubling and perhaps even tripling by mid-century.
Traditional risk factors for cardiovascular disease, including obesity, type 2 diabetes, smoking, high blood pressure and a poor cholesterol profile, are known to be associated with faster cognitive decline, although it’s difficult to isolate their individual effects. Xu and the study’s other authors, an international team of researchers from China, Sweden, the Netherlands and Rush University in the United States, decided to see if a standard cardiovascular risk-assessment tool — the Framingham General Cardiovascular Risk Scores (FGCRS) — might also be useful in assessing people’s long-term risk for cognitive decline. If the tool did prove useful, then it could be used to help identify individuals who would benefit the most from taking preventive steps to lower their risk of cognitive decline.
For the study, the researchers looked at data collected from 1,588 participants in the Rush Memory and Aging Project, a long-running study on aging and dementia that began recruiting people in 1997. As part of the study, the participants were given a series of tests annually to assess various memory and other cognitive skills. Starting in 2009, some of the participants also underwent magnetic resonance imaging (MRI) scans, which can reveal changes in the structures in the brain.
The participants were in their early 70s to mid-80s when they entered the study. At that time, none had dementia. They were then followed for up to 21 years — until 2019.
Using the health information gathered at the start of the study, the researchers calculated an FGCRS for each participant. They then used those scores to place each person into one of three cardiovascular-risk groups: lowest, middle and highest.
When all that data was analyzed, the researchers found that the participants with the highest risk of cardiovascular disease at the start of the study exhibited the fastest cognitive decline by its end. Three areas of cognitive skills showed the most decline: episodic memory (the ability to recollect previous events), working memory (the ability to recall and manage information recently acquired) and perceptual speed (the ability to quickly compare or differentiate between numbers, objects, pictures and other visual images).
The MRI data also revealed other worrisome associations. Higher FGCRS at the start of the study were associated with greater brain shrinkage, including of gray matter in the cerebral cortex, which controls many complex mental functions, and of the hippocampus, the brain’s memory center. Both of these changes are markers of the neurodegeneration associated with Alzheimer’s and other dementias.
The MRIs also showed a link between higher FGCRS and an increase of white spots on the brain (known as white matter hyperintensities). Such spots are associated with a decline in the brain’s functionality, including the ability to think and move quickly.
“Cognitive performance in different domains may indicate specific structural brain changes,” the researchers write in their paper. “Episodic memory and working memory decline may reflect hippocampal atrophy. Poor performance in processing speed was linked to white matter lesions.”
Limitations and implications
The participants in the study were volunteers, and three-quarters were women, which means the findings may not be applicable to the broader population. In addition, the participants they were mostly well-educated and performed relatively well on cognitive tests — although those factors suggest that the association between cardiovascular risk and later cognitive decline is underestimated in this study.
Of course, there’s a good reason heart health is important for brain health. The brain is, after all, a vascular organ. It needs a steady flow of healthy blood to provide it with oxygen and nutrients.
Knowing your cardiovascular risk can therefore help you take steps to not only protect your heart as you age, but also your brain.
“The Framingham General Cardiovascular Risk Score, which incorporates demographics and cardiovascular risk factors to assess cardiovascular risk, is also associated with vascular lesions in the brain and markers of neurodegenerative disease,” Xu and the study’s other authors conclude.
“Future studies should explore the mechanisms linking cardiovascular risk, neurodegenerative disease, and cognitive decline,” they add.
FMI: You’ll find an abstract of the study on the website for the Journal of the American College of Cardiology, although the full study is behind a paywall. For more information about cardiovascular-related factors and behaviors that support brain health during the aging process, go to the American Heart Association’s website.