Objective: Since hypertension is a major risk factor for multi-infarct
dementia, this study aimed to evaluate the effect of blood pressure o
n cognitive function in elderly subjects on no medication and disease-
free. Design: A cross-sectional survey. Setting: Community. Participan
ts: 598 healthy community-resident subjects aged 70 years and over who
were on no treatment. Measurements: Blood pressure (BP) and MMSE scor
e, 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 correlat
ed negatively with MMSE (P < 0.05), but diastolic BP showed no signifi
cant 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 systo
lic 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. Mult
ivariate analysis of variance found the differences between normal and
high to be significant at P < 0.001 for systolic and P = 0.001 for di
astolic BPs. Conclusion: High blood pressure is associated with cognit
ive impairment in healthy, drug-free, older people.