High blood pressure in otherwise healthy adults between the ages of 18 and 83 is associated with a measurable decline in cognitive function, according to a report published today by University of Maine researchers in the pre-publication online edition of the journal Hypertension. The article will appear in the October issue of the printed journal.
While they characterize the decline as "relatively minor and manageable in terms of everyday functioning," the authors underscore the importance of treatment for high blood pressure. In their study, younger individuals (18-47) performed at a higher level than older individuals (48-83), but they, like older individuals, showed blood pressure-related decline in cognitive function over time.
The study "breaks new ground," and "has far-reaching public health implications," according to an editorial by medical researchers in Belgium and the Netherlands published in the same issue of the journal. It extends what has been viewed as a problem of the elderly to younger people. Hypertension is published by the American Heart Association.
The authors are Penelope K. Elias, Merrill F. Elias and Michael A. Robbins of the UMaine Department of Psychology and Marc M. Budge of the Dept. of Geriatric Medicine, Canberra Hospital, Australia.
The report, titled Blood Pressure-Related Cognitive Decline: Does Age Make a Difference?, is based on an analysis of 20 years of blood pressure and cognitive performance data for 529 subjects in the Maine-Syracuse Longitudinal Study (MSLS) of Hypertension and Cognitive Functioning. That study was begun by Merrill Elias and David Streeten (Professor of Medicine) of the Health Sciences Center, State University of New York at Syracuse in 1974. It continues with grants from the National Institutes of Health, most recently the National Heart, Lung and Blood Institute and the National Institute on Aging.
Subjects in the study exhibited a normal range of cognitive functioning, as determined by the Wechsler Adult Intelligence Scale (WAIS). People suffering from dementia, diabetes, psychiatric illness, alcoholism, drug abuse or stroke were excluded.
The researchers analyzed data from four types of cognitive function tests focusing on visualization-fluid ability, memory, crystallized-verbal ability and speed. Only tests for visualization-fluid ability showed a statistically significant association with blood pressure in younger and older adults, aged 18-83.
Visualization tests included in the study measure abilities such as picture completion, picture arrangement, block design and object assembly. As a group, the tests require visualization and organization skills and the ability to solve novel problems under time constraints.
Other studies have related high blood pressure to cognitive decline but have not compared younger and older individuals and have not measured cognitive performance over an extended time period.
The results emphasize the importance of reducing high blood pressure even in younger adults, the researchers conclude. "To the extent that BP (blood pressure) effects on cognition are not reversible, it is important to prevent an increase in BP levels as early as possible in the life cycle," they conclude.
Across the population, lowering average systolic (the highest number in blood pressure tests) blood pressure by 20 millimeters mercury or diastolic blood pressure by 10 millimeters mercury would "have a considerable beneficial effect on the preservation of cognitive abilities in the population as a whole," they write.
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