Reducing CV Risk May Improve Brain Health at Any Stage in Life, Studies Hint

Striving for ideal cardiovascular health is a worthy goal on its own, but it may pay dividends in terms of brain function as well, both for younger and older individuals, two new studies published in the August 21, 2018, issue of JAMA indicate.

In a study of people 65 and older living in France, achieving optimal levels on a greater number of cardiovascular health metrics was associated with reduced risks of dementia and cognitive decline.

And another study in adults 40 and younger suggests that those who had a more ideal cardiovascular health profile had brain MRI findings indicative of better cerebrovascular structure and function, which could have implications for cognition later in life.

“Very often we think about the brain problems as one problem and then the heart disease problems as another,” Paul Leeson, PhD (University of Oxford, England), senior author of the latter study, told TCTMD, pointing out, however, that risk factors for cardiovascular and neurological diseases often overlap. “So there are common things we can do which are going to be beneficial for both heart health and brain health,” he said.

Lead author of the other paper, Cécilia Samieri, PhD (University of Bordeaux, France), told TCTMD the two studies are complementary, demonstrating “how prevention should be seen on a life-course perspective, starting as early as possible but also not forgetting people who get older and for whom prevention messages are really important, too.”

Protecting the Brain in Late Life

It has been known for a long time that specific CV risk factors—particularly in midlife—are associated with risks of dementia and cognitive decline at older ages, but there is little information available about the combined influence of several risk factors, Samieri noted.

To explore the issue, her team turned to the Three-City (3C) Study, which has been following people ages 65 and older living in Bordeaux, Dijon, and Montpellier, France, since 1999. The current analysis included 6,626 individuals (mean age 73.7; 63% women) who did not have a history of CVD or dementia at baseline.

The cardiovascular health of the participants was determined using a modified version of the Life’s Simple 7 tool from the American Heart Association (AHA), which assesses four lifestyle behaviors (eating a healthy diet, exercising, maintaining a healthy body weight, and not smoking) and three biological factors (blood pressure, cholesterol, and blood glucose). For each participant, the investigators both tallied the number of domains at “optimal” levels and calculated a global cardiovascular health score ranging from 0 to 14; each of the seven domains could receive 0 points for poor status, 1 point for intermediate status, or 2 points for optimal status.

Most participants (57.1%) had three or four domains at optimal levels, whereas 36.5% performed worse and only 6.5% better.

Through a mean follow-up of 8.5 years, 11.2% of people developed dementia, and there was an inverse correlation between CV health and risk.

In multivariable models, risk of incident dementia was a relative 10% lower for each additional CV metric at an optimal level (HR 0.90; 95% CI 0.84-0.97) and 8% lower for each additional point on the global cardiovascular health score (HR 0.92; 95% CI 0.89-0.96). Findings were similar when looking at declines in global cognition and memory.

The results support promotion of the Life’s Simple 7 tool, the researchers say.

“Each time you have one additional factor, you decrease your risk,” Samieri said. “So in terms of public health, it’s really less challenging to get this kind of recommendation than [it is to tell] people they should be perfect in terms of lifestyle and all the biological factors if they want to be protected from brain diseases. Here the message is more subtle, telling people, ‘Okay, even if it’s hard to get all the seven factors, do the best that you can and each additional good point really decreases your risk.’”

Threads Track Back to Early Adulthood

The study by Leeson, along with lead author Wilby Williamson, MSc (University of Oxford), and colleagues, suggested that it might never be too early to start trying to reduce cardiovascular risk.

The researchers performed brain MRIs on 125 adults 40 and younger (mean age 25; 49% women) who did not have clinical evidence of cerebrovascular disease and looked at how vessel characteristics and the presence of white matter hyperintensity lesions were related to eight measures of cardiovascular health, most of which overlapped with the Life’s Simple 7 tool.

On average, participants had six of the eight metrics at recommended levels. Each additional metric deemed ideal was associated with higher vessel density and caliber, fewer white matter hyperintensity lesions, and increased cerebral blood flow.

“These are young people. These aren’t changes which you would say are signs of disease there and then. But they’re early changes which we need to follow up and track,” Leeson explained, adding that some of these changes when seen later in life have been linked with risks of stroke and dementia.

The study complements the findings of Samieri et al, he said, showing that “the thread of these problems which appear in later life, you can track back possibly to these young adults, so that if you want to prevent those later problems actually it’s worth starting in the process very early on.”

Moving forward, it will be important to understand whether these risk factors can be modified at a young age to improve cognitive health later in life, added Leeson, who noted that his group is performing trials to tackle that question.

In an accompanying editorial, Jeffrey Saver, MD (University of California, Los Angeles), and Mary Cushman, MD (University of Vermont, Burlington), point out that neither of the two studies establish cause-and-effect relationships and both are subject to limitations.

Nevertheless, they conclude: “With these caveats and pending larger, longer trials, these two studies convey an immediately actionable message to clinicians, policy makers, and patients. Available evidence indicates that to achieve a lifetime of robust brain health free of dementia, it is never too early or too late to strive for attainment of ideal cardiovascular health. Avoid smoking, eat a healthy diet, be physically active, maintain normal weight, and keep blood pressure, cholesterol levels, and glucose-insulin levels low. Given the aging population, this positive health message is important to communicate to all members of society.”