Current and remote blood pressure and cognitive decline

Context Previous studies raise the possibility that blood pressure (BP) in middle age predicts later cognitive decline. Objective To examine prospectively the relationship of BP with level of and change in cognitive function in the elderly. Design Longitudinal, population-based study comprising subjects enrolled in the East Boston component of the Established Populations for the Epidemiologic Study of the Elderly (EPESE) (1982-1983) and the Hypertension Detection and Follow-Up Program (HDFP) (1973-1974). Setting East Boston, Mass. Participants Of the 3657 participants in the EPESE with baseline BP measurements, 2068 also participated in the HDFP. Subjects were aged 65 to 102 years at baseline in the EPESE and had mental status and memory assessed at baseline and 3 and 6 years. Main Outcome Measures Numbers of errors on the Short Portable Mental Status Questionnaire and the East Boston Memory Test and rates of change in these numbers of errors. Subjects had BP measured both at baseline in the EPESE and 9 years before, as part of the HDFP. Results In analyses adjusted for age, sex, and education, there was no strong linear association between BP and cognition. The associations found were fairly small in magnitude, and varied according to which test was used to measure cognition. There was little evidence for an effect of BP on change in cognitive function with either test, or for an effect on level of function on the memory test. In analyses of level of mental status questionnaire performance, however, elevated systolic BP (greater than or equal to 160 mm Hg)9 years before baseline was associated with a 14% (95% confidence interval [CI], 4%-25%) increase in error rate, relative to the referent (130-139 mm Hg). Baseline systolic BP had a U-shaped association with the number of errors; error rates were 9% higher compared with the referent group among those with systolic BP lower than 130 mm Hg (95% CI, 1%-17%) and 7% greater (95% CI, 0%-15%) among those with elevated systolic BP. Diastolic BP 9 years before baseline also had a U-shaped association with errors on the mental status questionnaire. Conclusion The findings do not suggest a linear association of BP with cognitive decline, but they are consistent with a more complex relationship between BP and cognition than previously appreciated.