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.