Abstract
The relationship between blood pressure (BP) and cognitive impairment (CI) and/or dementia (Dm) is more complicated than previously appreciated. In cross-sectional studies, some studies have shown positive relationship between higher BP levels and CI/Dm, while others have shown an inverse association. A U-shaped association was also reported.It is consistently reported that midlife hypertension can increase the risk for late age CI/Dm especially in those never treated with anti-hypertensive medication. Longitudinal studies on late life BP and subsequent CI/Dm have yielded mixed results. Reports that both low diastolic pressure and high systolic pressure in elderly persons were associated with subsequent development of CI/Dm might arbitrate such opposed views.High BP is positively associated with vascular CI/Dm, while it is inconsistently associated with Alzheimer disease. Several studies have shown that BP tended to decrease over the course of developing dementia. BP starts to decrease before dementia diagnosis and continues to decline afterward. Declining BP may be a consequence of the dementia process, while it is possible that low BP may predispose a subsequent development of dementia.Studies applying 24-hour BP monitoring showed increased nighttime BP patterns, non-dipper or riser, are strongly associated with CI/Dm. Non-dipper is considered to be associated with salt sensitive hypertension that is prevalent in Japan and reported to be ameliorated by the use of diuretics. Actually some reports suggested diuretic use was associated with reduced risk of CI/Dm. Especially for vascular dementia or Alzheimer disease with cerebrovascular disease, relevant use of diuretics may help preventing CI/Dm.
