Magnesium and Risk of Hypertension (page 1161)
Although dietary macro minerals, not only sodium and potassium but also calcium, are thought to play an important role in the primary prevention and control of high blood pressure, less attention has been paid to the possible effects of magnesium. Previous studies used circulating magnesium, which is regulated within a narrow, homeostatic range and may be compensated by magnesium from muscle and bone making it less reflective of dietary intake. Other studies relied on subjective measures of magnesium intake assessed by dietary recall, which correlates moderately with actual systemic magnesium absorption. In this issue of Hypertension, Joosten et al used urinary excretion of magnesium, as estimate of dietary uptake, to assess the association between magnesium and risk of hypertension. Two 24-hour urine collections were obtained from 5511 participants of the prospective, population-based Prevention of Renal and Vascular End-Stage Disease Study. Participants were free of hypertension at baseline and were followed for a median of 7.6 years. Urinary magnesium excretion was strongly and inversely associated with risk of hypertension. This association seemed to be independent of other dietary and nondietary risk factors of hypertension. As expected, no associations were observed between plasma magnesium and risk of hypertension. The current findings could have substantial public health implications given the highly prevalent inadequate magnesium intake in Western societies combined with the enormous burden associated with hypertension.
High Blood Pressure and White Matter Lesion Progression (page 1354)
Cerebral white matter lesions (WMLs) are highly frequent in the aging population and increase the risk of stroke and dementia. Slowing down the progression of WMLs can, therefore, potentially lead to a lower incidence of stroke and dementia. The exact pathogenesis of WMLs is still unknown, but converging evidence suggests that high blood pressure is one of the most important determinants for WMLs. Nevertheless, the longitudinal and temporal association between blood pressure and WMLs is not yet entirely elucidated. In this issue of Hypertension, Verhaaren et al report on a population-based MRI-study that investigated how blood pressure levels in the preceding 5 years were related to WML progression during the subsequent 3.5 years. They found that both high systolic and high diastolic blood pressure preceded WML progression and that antihypertensive treatment was associated with less WML progression. The results of Verhaaren et al further add to the evidence suggesting that high blood pressure is causally related to WML progression and indicate that antihypertensive treatment may be beneficial in reducing WML progression in the general population.
Blood Pressure Lowering and Cerebral Blood Flow in the Elderly (page 1309)
Hypertension frequently leads to adverse effects on the brain. Stroke was recognized as a complication long ago, but the association with cognitive decline and dementia is a more recent finding. Hypertension leads to increased rates of age-associated brain atrophy and small vessel disease which are likely to account for this association. The optimal treatment target for hypertension is unclear, particularly in older people, where many physicians are concerned about causing adverse events caused by brain hypoperfusion. It has been suggested that lowering blood pressure (BP) might accelerate small vessel disease progression. A better understanding of the effects of BP lowering on cerebral blood flow regulation in older people is required.
In this issue of Hypertension, Tryambake et al report a randomized controlled trial comparing the effect of 12-week intensive (target BP, <130/80 mm Hg) and usual (target BP, <140/90 mm Hg) BP lowering on cerebral blood flow using serial noninvasive MR arterial spin labeling. Cerebral blood flow increased by 10% with intensive BP lowering but was unchanged with usual BP lowering. These findings are contrary to what many physicians might predict but consistent with previous nonrandomized studies. These findings suggest that BP lowering more intensive than current guideline recommendations might benefit older people’s brains and support the undertaking of long-term intervention trials to determine whether more intensive BP reduces the risk of cognitive decline and dementia.
- © 2013 American Heart Association, Inc.