Ambulatory blood pressure as an independent determinant of brain atrophy and cognitive function in elderly hypertension

OBJECTIVE: Recent studies have demonstrated a relationship between brain atrophy and hypertension. Systolic hypertension in the elderly has been found to be a risk factor for cognitive impairment. We studied the relationship of ambulatory blood pressure with brain atrophy and cognitive function. METHODS: We performed ambulatory blood pressure monitoring and brain magnetic resonance imaging in 55 unmedicated elderly hypertensive patients (72.7 ± 6.0 years old). The volume of total brain matter was measured using an intensity contour-mapping algorithm. Cognitive function was assessed by mini-mental state examination score. RESULTS: Total brain matter volume and cognitive function were significantly correlated (r = 0.314, P = 0.02). Total brain matter volume was significantly negatively correlated with age (r = -0.365, P = 0.006), 24-h systolic blood pressure (r = -0.343, P = 0.01), awake systolic blood pressure (r = -0.278, P = 0.04) and sleep systolic blood pressure (r = -0.491, P = 0.0001), and significantly positively correlated with male sex (r = 0.493, P = 0.0001), body mass index (r = 0.282, P = 0.04) and nocturnal systolic blood pressure dipping (r = 0.323, P = 0.02). Mini-mental state examination score was significantly negatively correlated with age (r = -0.277, P = 0.04) and sleep systolic blood pressure (r = -0.360, P = 0.007), and significantly positively correlated with nocturnal systolic blood pressure dipping (r = 0.402, P = 0.002). In multiple linear regression analysis adjusted for age, sex, and body mass index, sleep systolic blood pressure (P = 0.009) was more significantly negatively associated with total brain matter volume than was either 24-h (P = 0.035) or awake (P = 0.020) systolic blood pressure. CONCLUSIONS: In elderly hypertensive patients, absolute ambulatory systolic blood pressure level (particularly during sleep) and nocturnal dipping in systolic blood pressure were strong indicators of brain matter volume and cognitive function.