Associations of ambulatory blood pressure levels with white matter hyperintensity volumes in hypertensive patients

OBJECTIVE: High daytime and nighttime blood pressure (BP) levels, and apparently also an abnormal nocturnal BP dip, coincide with a greater extent of cerebral white matter hyperintensities (WMHs). We assessed the relationship between ambulatory BP and volumes of WMH, and distinguished between periventricular and deep WMH because of their supposedly different cause. METHODS: A total of 210 hypertensive patients (106 men) without cardiovascular and cerebrovascular disease, with a mean age of 52.5 +/- 12.5 years, and untreated office BP levels of 170 +/- 24/104 +/- 12 mmHg underwent duplicate 24-h ambulatory blood pressure monitoring (off medication) and brain MRI to quantify the WMHs (total, periventricular, and deep) and brain volumes. We performed linear regression analyses to relate the mean 24-h, awake, and asleep BPs, and the relative nocturnal BP dip to the different volumes of WMHs, while adjusting for age, sex, brain volume, and vascular risk factors. RESULTS: Higher 24-h, awake, and asleep BP levels were continuously, without distinct thresholds, and independently associated with a greater volume of total (all P < 0.001), periventricular (P < 0.001), and, to a lesser extent, deep (P < 0.05) WMHs. Nocturnal BP dipping was not related to the volume of WMHs. CONCLUSION: Higher 24-h, daytime, and nighttime BP levels are independently associated with WMH volumes.