Mild hypertension may protect cognitive ability in independent people over age 70 years

Mild hypertension may protect cognitive ability in independent people over age 70 years, according to an article in the October issue of the American Journal of Hypertension.

Israeli researchers studied 142 men and 353 women, 51.1 percent of whom were actively receiving hypertension treatment. Of the total of 495 people, 385 completed the study. Of these subjects, 36 had normal blood pressure, 74 had normalized hypertension, 103 had untreated hypertension, and 172 had treated but uncontrolled hypertension. The mean age of subjects was 76.5 year, but the people with normal blood pressure were younger than the people in the other groups.

"As expected at this age group, most of the respondents (71.5 percent) were women, and less than half (44.3 percent) were currently married," the researchers reported. "Some three fifths continued their education beyond high school."

All 4 groups completed a battery of cognitive tests that measured memory, concentration, visual retention, verbal fluency and the mini-mental state examination. Of the 5 cognitive domains tested, only verbal fluency was not related to hypertension status.

"After adjusting for confounding variables, treated but uncontrolled hypertensives performed significantly better than at least one of the other groups, and normotensives performed poorest," the researchers said. "It is worth noting that normalized hypertensives generally performed better than normotensives, but the differences were not statistically significant.

"Systolic and diastolic blood pressure were related to memory, visual retention, and moderate concentration," the authors explained. "Systolic blood pressure values were also positively related to mini-mental state examination scores."

The mean blood pressure of people with treated but uncontrolled hypertension, the study group with the highest cognitive scores, was 158.6/85.4 mm Hg, which was within the hypertension treatment values recommended by the World Health Organization until the 1990s.

"Examining blood pressure values as a continuous variable enabled us to search for various models of relationship with cognitive functioning," the authors wrote. "We found support for the hypothesis that the association between blood pressure and different dimensions of cognition take on different patterns.

"Thus, mini-mental state examination scores and the lighter concentration task were linearly related to blood pressure, whereas memory and visual retention improved with an increase in blood pressure up to a point beyond which cognitive performance leveled or even reversed."

The authors concluded that the benefits of reduced blood pressure in the elderly "entail cognitive costs, and these costs may vary from one cognitive domain to the other. Practitioners will have to provide their patients with complicated information, and help them reach educated decisions regarding their choices."

"The study by Paran and colleagues counters conventional medical science beliefs that hypertension accelerates age-related mental decline," said Michael A. Weber, MD, an editor of the American Journal of Hypertension. "Previous studies yielded mixed and inconsistent results but Paran and colleagues found support for the hypothesis that the association between blood pressure and different dimensions of cognition take on different patterns.

"The results of this Israeli study could present a dilemma for physicians to choose between cardiovascular health and cognitive health in treating elderly people with high blood pressure," he added. "Further study is required to weigh the proven longevity benefits of blood pressure control with the new finding of cognitive protection. Until further evidence comes along, it would be most prudent for clinicians to achieve currently recommended treatment goals in their patients."

 


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