Journal Report
10/04/2004

Mental function declines when blood pressure rises in young adults

DALLAS, Oct. 5 – Young people with high blood pressure are just as susceptible to decreased mental function as are elderly people with high blood pressure, according to a study reported in Hypertension: Journal of the American Heart Association.

Several studies have shown that high blood pressure, or hypertension, correlates with poorer cognitive performance in older adults.  This study found that higher blood pressure was linked to a decline in cognitive function in otherwise healthy people 18 to 46 years of age, as well as those who were older.  Some participants in the study were followed for almost 20 years, making it one of the longest studies of blood pressure’s effects on cognitive performance.

Early, aggressive efforts to prevent and treat hypertension regardless of a patient’s age is needed, said co-author Merrill F. Elias, Ph.D., MPH, professor of psychology and professor of epidemiology in the department of independent studies at the University of Maine in Orono, Maine.

“We need to be concerned about blood pressure effects on cognitive performance in older people, but we also need to be concerned about the relationship between blood pressure over time and the change in cognition in younger people,” he said.

Most previous data has come from studies involving middle-aged and older individuals, and many studies based their results on relatively few evaluations of cognitive function, said Elias.

“The study also was prospective in that we looked at baseline blood pressure and related it to cognitive function over many years.  A number of other studies have just looked at blood pressure at one point in middle-aged people and they found that blood pressure correlated with cognitive function at some later point in time.”

The current study involved 529 participants in the Main-Syracuse Longitudinal Study of Hypertension, whose first patients were enrolled in 1976-77.  Blood pressure was evaluated at baseline and during up to four follow-up visits.  Participants underwent a standardized test of cognitive function at baseline and at each follow-up.  For data analysis, the participants were divided into two age groups: 18 to 46 years and 47 to 83 years.

In both age groups, the analysis showed that over time higher blood pressure correlated with a decline in the cognitive function known as “visualization/fluid abilities” – the ability to react and respond to novel information, Elias said.

“As an example, you might be presented with some relatively complex visual material that you’ve not seen before and have to organize it in a certain way or remember the relationships among items in the material,” he said. 

“Using the 7^th report JNC [Joint National Committee on the Prevention, Detection, Evaluation and Treatment of High Blood Pressure] classifications, moving from the ‘Normal’ blood pressure to the ‘Stage 1 Hypertensive’ classification (2 steps) results in an estimated 8.12 percent decrease in visualization/fluid abilities over 20 years.”

The other functions tested – verbal, memory and speed abilities – were not related to cognitive decline.

Baseline mean arterial pressure (MAP), reflecting the difference between systolic and diastolic pressure was also correlated to a decline in cognitive function in the older patients. Elias said that MAP is one indication of age-related stiffening of blood vessels.

“The effects of hypertension on cognitive function are chronic and long term,” Elias said. “We need to do whatever we can to prevent blood pressure from rising to begin with, but when blood pressure does increase, it needs to be treated promptly.  We shouldn’t hesitate to treat younger people.”

He also suggested that “lowering systolic blood pressure by just 20 mm Hg or diastolic pressure by 10 mm Hg would have a considerable beneficial effect on the preservation of cognitive abilities in the population as a whole,” Elias said.

In an accompanying editorial, Jan A. Staessen and Willem Birkenhäger, University of Leuven, Belgium and Erasums University in Rottendam, the Netherlands, suggested that the study has far reaching public health implications.  “In the United States the prevalence of Alzheimer’s disease will quadruple over the next 50 years and affect one in every 45 Americans. … Clinical trials must be mounted specifically to address the questions of whether blood pressure-lowering [agents] can prevent Alzheimer’s disease.”

The first author of the study is Penelope K. Elias, Ph.D., and co-authors are Michael A. Robbins, Ph.D., and Marc M. Budge, M.B.B.S., B.Sc.Med.

The National Institute on Aging and the National Heart, Lung, and Blood Institute funded this research.

NR04 – 1314 (Hypertension/Elias)

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