Blood pressure and cognitive functioning among independent elderly

BACKGROUND: The morbidity and mortality benefits of blood pressure (BP) control for the elderly is well documented. The cognitive consequences of hypertension control in this population, however, are still under debate. We aim to study the association between BP and cognitive performance in the elderly. Specifically, we explore 1) the possibility that BP is differentially associated with various cognitive domains; and 2) the utility of analyzing both BP and cognitive scores as continuous variables to unravel possible nonlinear associations. METHODS: Four hundred ninety-five community living 70 to 85 year olds completed eight cognitive tests that measured memory, concentration, visual retention, verbal fluency, and the mini-mental state examination (MMSE). The performance of each test was analyzed first by comparing four groups (normotensives, normalized hypertensives, untreated hypertensives, and treated but uncontrolled hypertensives). Then, using BP values as continuous variables, linear, U-curve, and J-curve associations were estimated. RESULTS: On all cognitive tests, except for verbal fluency, normotensives performed poorest, treated but uncontrolled hypertensives achieved the highest scores. The MMSE scores and the lighter concentration task were linearly related to BP; J-curve association was observed between memory and visual retention; prolonged concentration was related to pulse pressure alone. CONCLUSIONS: Low BP, as observed among the normotensive subjects, was associated with poor cognitive performance. Mild hypertension appeared to enhance cognitive functioning among the subjects of this study. Moreover, we found support for the hypothesis that the association between BP and different dimensions of cognition take on different patterns.