Blood Pressure and Cognitive Function in Healthy Old People

OBJECTIVE: Since hypertension is a major risk factor for multi-infarct dementia, this study aimed to evaluate the effect of blood pressure on cognitive function in elderly subjects on no medication and disease-free. DESIGN: A cross-sectional survey. SETTING: Community. PARTICIPANTS: 598 healthy community-resident subjects aged 70 years and over who were on no treatment. MEASUREMENTS: Blood pressure (BP) and MMSE score, an index of cognitive function. RESULTS: Mean age of the sample was 75.7 years, mean BP 160/86 mmHg, mean MMSE 28.0. Systolic BP correlated negatively with MMSE (P < 0.05), but diastolic BP showed no significant overall correlation. To study possible J-shaped curve effects of BP, the sample was stratified into three groups--low BP, normal BP, and high BP--at levels one standard deviation from the mean for both systolic and diastolic pressures. Mean MMSE scores for low, normal and high systolic BP were 28.3, 28.1, 27.5, respectively; for low, normal, and high diastolic BP scores were 28.0, 28.1, and 27.5 respectively. Multivariate analysis of variance found the differences between normal and high to be significant at P < 0.001 for systolic and P = 0.001 for diastolic BPs. CONCLUSION: High blood pressure is associated with cognitive impairment in healthy, drug-free, older people.