Differences in the association between high blood pressure and cognitive functioning among the general Japanese population aged 70 and 80 years: The SONIC study

High blood pressure in middle age (up to 64 years) has been proposed as a predictive indicator of dementia. However, the association between hypertension and the cognitive functioning is controversial in older age groups. The aim of this study was to investigate this association in 70-80-year-old participants in the Japanese study of Septuagenarians, Octogenarians and Nonagenarians Investigation with Centenarians (SONIC). Participants aged 70 (+/- 1) and 80 (+/- 1) years (n = 1000 and 973, respectively) were randomly recruited from the general population in Japan. Cognitive functioning was measured by the Montreal Cognitive Assessment. Blood pressure and other medical and social variables were analyzed by multiple regression analyses. High systolic blood pressure (SBP) was significantly correlated with a reduced cognitive functioning only in participants aged 70 years. Additionally, this correlation became more marked in participants with uncontrolled blood pressure at age 70 years. In contrast, SBP was not significantly correlated with the cognitive functioning at age 80 years. Nutritional status indicators such as serum albumin and frequency of going outdoors were significantly associated with cognitive functioning at age 80 years. Our findings indicate that high SBP has a significant role in cognitive functioning at age 70 years; however, blood pressure is less important as a risk factor for cognitive decline at age 80 years.