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AORTIC BLOOD PRESSURE IS ASSOCIATED WITH WHITE MATTER HYPERINTENSITY FRACTION IN POSTMENOPAUSAL WOMEN WITH NORMAL BLOOD PRESSURE

      Background: White matter hyperintensity (WMH) load on T2-weighted MRI is a risk factor for cognitive impairment. Hypertension is associated with high WMH load, suggesting a vascular etiology. However, the relationship of blood pressure (BP) within the normal range and WMH is not established. Elevations in aortic hemodynamics precede the appearance of clinically-diagnosed hypertension. In normotensive individuals, noninvasive measurements of aortic hemodynamics provide information on vascular function. Early alterations in aortic hemodynamics may be mechanistically linked to the development of WMH. In this context, the hormonal shifts during menopause accelerate vascular dysfunction in women, putting postmenopausal women at increased risk for both hypertension and WMH. Our objective was to determine the association between aortic hemodynamics and WMH in healthy, postmenopausal women with normal blood pressure.
      Methods: We examined 39 non-hypertensive postmenopausal women (age 60±3 yrs; body mass index 27±4 kg/m 2). Mean arterial blood pressure (MAP) was determined using a brachial arm cuff and was within normal range (88±7 mmHg). Aortic hemodynamics were estimated using beat-by-beat tonometry (Sphygmocor). WMH was calculated from fluid-attenuated inversion recovery MRI using a semi-automated segmentation algorithm. WMH volume was divided by the total white matter volume to calculate WMH fraction in each subject.
      Results: Aortic hemodynamics included systolic BP (112±10 mmHg) and diastolic BP (74±7 mmHg). WMH fraction was positively associated with aortic systolic BP (r=0.40;p<0.01) and aortic diastolic BP (r=0.33;p<0.05). After adjusting for age, aortic systolic BP and WMH remained significantly associated (p=0.03). Age and diastolic BP had a significant interaction (p=0.02), with WMH fraction increasing less with aortic diastolic BP in older ages.
      Conclusions: In postmenopausal women with normal blood pressure, higher aortic systolic pressure was associated with greater WMH load. Because increases in aortic hemodynamics precede changes in brachial cuff BP measurements, our results suggest that monitoring aortic hemodynamics may identify individuals at accelerated risk for WMH and guide early treatment to reduce development of WMH and cognitive impairment.