See related article, p 1333–1338

Dementia represents an important public health issue in developed countries because of increasing longevity of the elderly population.1 Cerebral damage is mediated by changes in cerebral vasculature affecting both large and small vessels.2 The microvascular disease results in chronic ischemic changes affecting the white matter, which in the long run can lead to cognitive alterations, which may progress to overt vas-cular dementia.2 It is thus important to identify and counter-balance the risk factors for cognitive decline at a population level. Although high midlife blood pressure (BP) is associated with an increased risk of late-life dementia,3,4 the pathophysiol-ogy of the relationship between elevated BP and low cognition remains unclear. In particular, it is uncertain whether, to pre-serve cognition, it is better not only to lower the mean BP level but also to achieve a more stable BP. Both high and, especially in the elderly, low BP have been linked to cognitive declin