Cognitive function and dementia in hypertension: Epidemiologic and therapeutic aspects

Hypertension and dementia are both common and increasingly important disorders in aging populations. As the two most common causes of dementia, Alzheimer's disease and vascular dementia often overlap and share vascular risk factors including hypertension, there is strong potential for blood pressure-lowering treatment to reduce the risks of dementia and cognitive decline. In this chapter, we review observational studies and randomized trials that have investigated blood pressure and the effects of blood pressure-lowering treatment on the risk of dementia or cognitive impairment. Observational studies indicate that high levels of blood pressure in midlife (40-64 years) predict dementia in later life, particularly vascular dementia, although the role of high blood pressure specifically in late-life (≥65 years) remains uncertain. Although several observational studies suggest protective effects of blood pressure-lowering treatment on the risk of dementia, the totality of the randomized evidence is still insufficient to confirm the potential for modest benefits of blood pressure-lowering on dementia. However, given the direct effects of blood pressure-lowering in reducing the risk of stroke and of stroke-associated dementia, it seems reasonable to propose that as more evidence accrues, blood pressure-lowering will at least be shown to have beneficial effects on vascular dementia and possibly on Alzheimer's disease, too.