“By age 70, about 15 percent of people have vascular disease in the brain,” says Prashanthi Vemuri, a Mayo Clinic researcher who studies cognitive decline. “By age 90, about 70 percent have it.”
But the damage to blood vessels in the brain often starts in your 40s and 50s. And there’s something you can do to help prevent it.
On brain scans, the damage shows up as infarcts—brain cells that have died from lack of oxygen after tiny blood vessels ruptured or became blocked. Or it may show up as damage to the brain’s white matter, which contains bundles of nerve fibers. “The white matter starts deteriorating,” says Vemuri.
The vulnerable part of your brain
“The areas in the frontal lobe of the brain that are most important for executive function, planning, and learning are particularly vulnerable to damage caused by blocked blood vessels,” says Patrick Smith, assistant professor of psychiatry and behavioral sciences at Duke University School of Medicine.
That’s less of a problem in some other parts of the brain. “Areas like the occipital lobe for vision get multiple feeds of blood from different areas,” explains Smith.
But in the frontal lobe, there’s less redundancy. “So you see damage in the watershed brain regions, where a blockage in one part of the artery causes a lot of white matter damage downstream.”
The small infarcts that result from the blockages are pretty common. “Most people don’t even know they’ve had them,” says Smith. The same is true with white matter damage.
“And both are related to blood pressure,” Smith explains.
So, could a diet that lowers blood pressure also improve thinking ability?
To see, Patrick Smith and his colleagues recruited 124 sedentary overweight or obese adults with pre-hypertension or hypertension. (Based on those criteria, most Americans would have been eligible for the study.)
The researchers randomly assigned them to one of three groups: a DASH diet alone, a DASH diet with fewer calories plus exercise, or their usual diet.
The government-developed DASH (Dietary Approaches to Stop Hypertension) diet and a modified version called the OmniHeart diet have been proven to lower blood pressure.
“We were surprised at the results,” says Smith.
“Even though it was only a four-month intervention, we saw improvements in executive function, processing speed, and some aspects of learning and memory in the group that got the weight-loss DASH diet and aerobic exercise.” The DASH diet alone improved processing speed.
Those most at risk benefited the most
“People who started out with greater thickness in the walls of their carotid arteries seemed to experience a greater improvement in cognitive function,” says Smith. “The carotid artery wall is a barometer of cardiovascular risk, so those are people who were at greater risk for stroke or future heart problems.
“One thing that we’ve learned over the past few decades is that progressive cognitive problems happen over the course of decades,” adds Smith. “So controlling your cardiovascular risk factors—getting high blood pressure and high cholesterol into the normal range—could make a big difference over time.”
Here’s more information about the DASH-OmniHeart diet, which is widely acclaimed as the healthiest diet to lose weight and lower blood pressure.
Source: Hypertension 55: 1331, 2010.
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