Blood pressure and cognitive decline in healthy old people

Both hypertension and cognitive decline are common in old age. We sought to examine the effects of blood pressure (BP) on rates of cognitive decline in a longitudinal study of community-resident healthy old people. A total of 603 initially healthy old people aged over 69 years were visited at home. Subject's age, years of full-time education, Social Occupational Classification, health status and medication use were recorded. Sitting systolic and diastolic BP was measured, and the Mini-Mental State Examination (MMSE) and National Adult Reading Test (NART) administered. Follow-up was planned after: 4 years: 69 subjects were dead, 15 were too unwell and 12 had moved away; 78 subjects either refused or failed to reply. Psychometric tests were administered to the remaining 429 (71.1%) after a median period of 4.20 years. Forty-two subjects had significant sensory impairment or interrupted testing. No significant differences in cognitive decline were found between those who had started medication (n = 163) and those remaining untreated (n = 224). Mean MMSE score change was 0.44 points (s.d. 2.07, P<0.001). Entering all baseline variables into a stepwise regression analysis significant positive effects were found for initial MMSE score (beta = 0.50, P < 0.001), age (beta = 0.17, P < 0.001), systolic BP (beta = 0.16, P < 0.001) and period between testing (beta = 0.14, P = 0.004), and negative effect for NART-predicted IQ (beta = -0.16, P = 0.003).). We conclude that (1) older people exhibit faster age-associated cognitive decline as measured by MMSE; (2) people with higher NART-predicted IQs are relatively protected; (3) people with high systolic BPs are at greater risk of cognitive decline.