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Elderly Blood Pressure Variability Affects Cognitive Function

NEW YORK, N.Y. -- May 26, 2006 -- Cognitive function is adversely affected by exaggerated variability between systolic and diastolic blood pressure (BP) in elderly patients 80 years of age and older, according to a study presented here at the 21^st Annual Scientific Meeting of the American Society of Hypertension (ASH 2006).

The researchers measured blood pressure and cognitive function in 101 Japanese outpatients receiving treatment for chronic diseases such as hypertension, hyperlipidemia, diabetes, chronic gastritis, and osteoporosis.

"Although clinicians may be reluctant to treat older patients aggressively, perhaps because of perceived lower benefits or possible increased risk of medication side effects, these findings show the potential value of interventions," said Kenichi Sakakura, MD, Public Kiwa Clinic, Kumano, Mie, Japan.

The purpose of the study was to evaluate the association between pulse pressure and cognitive function in a cohort of very elderly patients, specifically those over 80 years old. Blood pressure was measured via 24-hour ambulatory blood pressure monitoring (ABPM) and cognitive function was evaluated with the Mini-Mental State Examination (MMSE), an 11-question measure with a maximum score of 30 points that tests 5 areas of cognitive function: orientation, registration, attention and calculation, recall, and language.

The cut-off score for the MMSE was 24 points. Standard deviation (SD) of daytime systolic blood pressure (SBP) was also calculated as a measure of blood pressure variability.

Results showed a mean 24-hour systolic BP of 138.1 ± 17.6 mm Hg and diastolic BP: of 75.9 ± 8.0 mm Hg. Mean MMSE score was 23.1 ± 4.2, and of those, 55.4% of patients were diagnosed with cognitive dysfunction (<24 points).

MMSE scores decreased across the tertiles of standard deviation of systolic BP readings (P =.02), indicating lower functioning, but remained significant after controlling for daytime systolic BP levels, confirming an independent relationship between exaggerated blood pressure variability and cognitive dysfunction in the elderly.

Previous research published in Hypertension: Journal of the American Heart Association in 2004 evaluated blood pressure effects on cognitive performance on 529 patients who were divided into 2 age groups (18 to 46 years and 47 to 83 years). The data showed that there was a correlation between higher BP and decline in cognitive function over time in both age groups. The lead investigator of that study suggested that lowering the systolic BP by 20 mm Hg or diastolic blood pressure by 10 mm Hg would have a considerable beneficial effect on the preservation of cognitive abilities in the whole population.

Calling for further investigation, Dr. Sakakura also said, "These results further validate previous indications that variable blood pressure has an effect on cognitive function in the very elderly. However, very little data exists to support these theories, and more research is needed to confirm the full impact of blood pressure on cognitive function in these patients."


SOURCE: American Society of Hypertension

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