Cerebral blood flow in the elderly: impact of hypertension and antihypertensive treatment.

The subject of the cerebral circulation in the elderly is reviewed. In old age, cerebral blood flow (CBF), which is closely coupled to cerebral oxidative metabolism, decreases along with the amount of brain tissue. In healthy old people, the cerebral circulation is regulated as earlier in life, by autoregulation, metabolic regulation, and chemical and other factors. CBF and its regulation is influenced by disease processes prevailing in old age, such as dementia, atherosclerosis, diabetes mellitus, stroke, and hypertension. Hypertension, apart from being a risk factor for stroke, causes adaptive cerebral vascular changes, leading to a shift of the lower limit of autoregulation towards high pressure, with an impaired tolerance to pressure decrease. In old age, this adaptation may not be reversible. With this background, a conservative approach to elderly hypertensive patients is suggested, aimed at some reduction of pressure but carefully avoiding overtreatment.