Blood pressure and performance on the Mini-Mental State Examination in the very old. Cross-sectional and longitudinal data from the Kungsholmen Project.

Abstract

The authors examined the association of blood pressure with cognitive function as assessed by the Mini-Mental State Examination (MMSE) in a community-based Swedish cohort of 1,736 people aged 75-101 years. Age, sex, education, antihypertensive medication use, heart disease, and stroke were considered as covariates. Multiple linear regression analysis indicated that both systolic and diastolic blood pressure, measured in 1987-1989, were positively and significantly related to baseline MMSE score; baseline systolic pressure was also positively and significantly related to follow-up MMSE score, measured after an average period of 40.5 months among subjects who were not taking antihypertensive medication at baseline. Furthermore, in the nontreated group, multiple logistic regression showed that individuals with a baseline systolic pressure less than 130 mmHg had an odds ratio of 1.88 (p = 0.05) for follow-up cognitive impairment (MMSE score < 24) compared with those whose systolic pressure was 130-159 mmHg. An increased but not statistically significant risk of cognitive impairment was associated with high blood pressure (systolic pressure > or = 180 mmHg or diastolic pressure > or = 95 mmHg) only in persons taking antihypertensive medication at baseline. Subjects with systolic pressure of 160-179 mmHg tended to be at lower risk of cognitive impairment. These results may support the view that a certain blood pressure level, particularly a systolic pressure of at least 130 mmHg, is important to the maintenance of cognitive functioning in the very old. They also suggest that severe hypertension that is not well controlled (systolic pressure > or = 180 mmHg or diastolic pressure > or = 95 mmHg) is still a threat to cognitive function in this age group. However, the use of blood pressure measurements made at a single visit and the relatively short follow-up period should be considered when interpreting these results.