Higher blood pressure may actually provide an unexplained health benefit and boost longevity for extremely frail elderly adults, a surprising new study suggests.
The research, published in the Journal of the American Medical Association's Archives of Internal Medicine, found that lower blood pressure protects healthier older adults, but may not have the same effect in their more frail counterparts.
"Our study supports treating high blood pressure in healthy, active older adults. But in frail older adults, with multiple chronic health conditions, we need to take a closer look at what sorts of effects high blood pressure could serve and whether having a higher blood pressure could be protective," said Michelle Odden, a public health epidemiologist with Oregon State University who helped conduct the study.
"As we age, our blood vessels lose elasticity and become stiff. Higher blood pressure could be a compensatory mechanism to overcome this loss of vascular elasticity and keep fresh blood pumping to the brain and heart."
For the study, Odden and her colleagues tracked a nationally representative group of 2,340 adults ages 65 and older. Participants were asked to walk about 20 feet at their normal rate to gauge their degree of frailty. Those who walked less than 0.8 meters per second were defined as frail, slower walkers. Those who walked faster than 0.8 meters per second were deemed more robust adults, who also had a lower prevalence of diabetes, coronary heart disease, stroke and heart failure. And a third group included those who were not able to complete the walking test for various reasons, including inability to walk 20 feet.
Among fast walkers, those with high blood pressure had a 35 percent greater risk of dying compared with those with normal blood pressure. By contrast, there was no association between hypertension and mortality in the slow-walking group. But those who were unable to complete the walking test who also had higher blood pressure had a 62 percent lower mortality rate.
Odden said the mortality differences between the fast-, slow- and non-walkers are evidence that everyone ages differently.
"There is a profound difference in the physiological age of an 80-year-old man who golfs every day, and someone who needs a walker to get around," she said. "So in the fast walkers, high blood pressure may be more indicative of underlying disease, not just a symptom of the aging process."
The study was funded by the National Institute on Aging and the American Heart Association.