OUR RECENT observations1 have shown that the cerebral blood flow and metabolism in persons over 50 years of age with evidence of cerebral vascular disease is significantly reduced from that of both normal young and elderly patients. It is conceivable that elderly patients with hypertension and cerebral arteriosclerosis may be unable to compensate by vasodilatation for a relatively sudden decrease in systemic blood pressure. Under such conditions a pathologically more sluggish cerebral circulation may result which may predispose to the formation of cerebral thrombosis. It was thought that studies of the effect of artificially induced hypotension on cerebral hemodynamics in this group of patients might help to elucidate the problem.
Subjects selected for this study were over 50 years of age and had hypertension (mean arterial pressure over 110 mm. Hg) and cerebral vascular disease. The latter was determined by the presence of any two of the following