The impact of high blood pressure: salt and stress and "senior moments"
By Josh Fischman
"Senior moments."
Admit it: It's a little harder to keep track of things as you age, or maybe it just takes a little extra effort to wrestle a fact from deep in your memory to the front of your consciousness. Blood pressure, too, tends to creep up as you age–and there may be a connection between the two.
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High blood pressure means you have a reading of 140 over 90, or higher, when someone straps a blood pressure cuff on you. Last week, at an American Heart Association conference on blood pressure, researchers reported on some brain scans of 60-year-olds who had such high readings. Richard Jennings , a psychiatrist at the University of Pittsburgh, and his colleagues compared one group above the high b.p. threshold with another group below it. Both groups were asked to do computer exercises, like trying to recall the location of a flashing square on the screen while tapping different fingers. The idea was to simulate the kind of memory task involved when you try to remember a phone number while walking from one room to the phone in the next room. (If you can't recall the number when you get there, that's a classic "senior moment.")
Brain scans done while all this was going on showed that hypertensive people had slightly less blood flow in areas at the back of the brain involved in memory. And, Jennings says, they also scored a bit lower on memory tests. It was a slight difference, but a noticeable one. What may be happening is that blood vessels may be reacting to high pressure by remodeling themselves. Vessels can actually shrink or stiffen, as a way to reduce what appears to be excess blood volume shooting through. If such changes become too extreme, however, blood flow to and in the brain is reduced, and that may explain the poorer memory. Drugs that correct such vessel shifts, known as ACE inhibitors, might make senior moments less momentous.
Salt and stress
Another group with more than their share of high blood pressure are African-Americans. They have a much higher rate of hypertension than do Caucasians. Scientists have speculated that blacks may react to stress more strongly than whites and that the reactions damage blood vessels, eventually leading to higher pressure. Others think the culprit may be salt: Blacks have less ability to regulate salt's effect in the body, and one such effect is to drive up blood pressure.
The two–salt and stress–may actually work together, researchers suggested this week at a meeting of the American Physiological Society. The scientists looked at about 220 blacks and whites with similar salt levels. Then they tried to stress everyone out. People had to play a competitive video game for one hour. Then they had a two-hour recovery period. The stress appeared to affect African-Americans' ability to regulate salt–it was measured in their urine–to a greater degree, and two hours after the video game workout, their blood pressure was indeed higher. This is called "stress-induced salt sensitivity," and the scientists think it's a major reason for the racial pressure difference. That's a difference that eventually shows up in high rates of heart disease, stroke, and diabetes.
