Cardiac index -- the
measure of how well the heart is pumping blood to the brain and the rest
of the body -- may be an indicator of a person's risk for developing
dementia in the future.
A study in this week's Circulation suggests cardiac index is
linked to brain size, even in people without heart disease, a known risk
factor for dementia.
"The primary finding is that cardiac index is associated with
brain volume. Participants with low cardiac index and low normal values
had smaller brains, equivalent to about two years of brain aging
compared to those with high cardiac index," says study author Angela
Jefferson, associate professor of neurology at the Alzheimer's Disease
Center at Boston University School of Medicine.
The study evaluated data from 1,504 participants in the
Framingham Offspring Cohort, an arm of the larger Framingham Heart
Study. Information was collected from neuropsychological tests, brain
and cardiac MRI and lab reports.
Doctors have long known that the heart and brain are
intertwined and that heart disease is a risk factor for dementia and
Alzheimer's, says Richard Lipton, an attending neurologist at Montefiore
Medical Center and professor of neurology at the Einstein College of
Medicine in New York. But he says these results take into account
non-heart patients, too.
"These are not people with heart disease, so that's what makes it interesting," Lipton says.
Will the results translate into public-health recommendations?
"I'm not entirely sure yet. But I think sometimes we give drugs that
reduce high blood pressure, that (also) reduce cardiac index, and maybe
people will begin to think twice about that," he says.
William Borden, assistant professor of medicine in public
health at the Perelman Heart Institute at New York-Presbyterian
Hospital/Weill Cornell Medical Center, says the study "helps give us a
better understanding of what potentially could lead to dementia in older
people, and the role that cardiac dysfunction, or weak hearts, play in
brain function or dysfunction."
"But we don't want to overstate the article," he says. "It is
important, certainly suggestive, but it is observational data and can't
prove anything just yet."
Author Jefferson, who says she plans to continue studying the
relationship of cardiac index to cognitive health, concurs: "It's
premature to say you can take this medication or engage in this
particular activity to improve your cardiac output to protect brain
But, she says, it's still fair to encourage people to engage in
healthy living choices: "Eat well, exercise regularly, and take
medicines prescribed by your doctor if you have cardiovascular risk
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