Relation of Hypertension, Nocturnal Blood Pressure Variation, and Family History of Hypertension to Cognitive Decline and Brain Aging in Older Adults

Abstract

Blood pressure (BP) in healthy individuals typically exhibits normal diurnal variation ("nocturnal dipping"), with nighttime systolic reductions of 10-20%. Having sustained BP levels, without normal nocturnal dipping, has been associated with increased risk for cardiovascular disease and poorer performance on memory measures especially within the context of hypertension. A positive family history of hypertension has also been related to poorer performance on neuropsychological tests of visuospatial/constructional ability, verbal learning, attention, and memory. The present study investigated the effect of nocturnal BP dipping status in hypertensive and normotensive individuals, with and without a family history of hypertension, to determine if these factors contributed to declines in cognition and brain atrophy over a two-year period in otherwise healthy older adults. Eighty-one neurologically healthy older adults aged 68-89 received a battery of neuropsychological tests, 24-hour ambulatory BP monitoring, structural magnetic resonance imaging, health screening and questionnaires at baseline. Two-years later participants received follow-up neuropsychological testing and structural magnetic resonance imaging. Analysis of variance investigated the effects of age, nocturnal BP dipping status, hypertension, and family history of hypertension on residualized change scores for measures of memory, executive function, and processing speed. Additionally, multivariate analysis of variance was used with region of interest measures of brain structure to evaluate the effects of age, nocturnal BP dipping status, hypertension, and family history of hypertension on brain atrophy. Results indicated main effects for dipping status with non-dippers showing poorer performance on measures of memory compared to dippers. An interaction between nocturnal BP dipping and hypertension status was also observed on a test of executive functioning, with non-dipping hypertensives performing more poorly than the dipping groups, indicating that the combination of hypertension and non-dipping nocturnal BP was associated with poorer cognitive performance. Results indicated that non-dipping BP status was related to greater decline in cingulate volume and the combination of non-dipping and hypertension was related to greater decline in right hemisphere frontal surface area measures. These results provide some support indicating that having sustained diurnal systolic BP without normal nocturnal reductions in hypertension may be an important vascular risk factor influencing the course of cognitive and brain aging.