rationale for not recommending treatment for high blood pressure; it should be noted, however, that the size of the samples used in these clinical trials were inadequate to test a hypothesis with regard to effects of treatment on total mortality. When the results of all randomized trials of the treatment of diastolic high blood pressure were recently pooled in a meta-analysis, it appeared that a small but significant reduction in total mortality may have occurred across all age groups.42 The data are inadequate, however, to draw conclusions about the impact of the treatment of high blood pressure on total mortality in persons over the age of 50.
Concerns about toxicity resulting from antihypertensive therapy in the elderly have led many authors to advise restraint or even therapeutic nihilism with respect to the treatment of high blood pressure in this group.76 Theoretically, there are several reasons why the risk/benefit ratio for the treatment of high blood pressure might increase with age. It is believed that the elderly are particularly susceptible to many of the side effects of antihypertensive medication.34,76 For instance, elderly patients are more likely to develop hyponatremia and hypokalemia when treated with standard doses of diuretics.27,34 It is also thought that older patients are more likely to develop side effects such as depression and confusion when treated with antihypertensive medications that affect the central nervous system (e.g., beta-blockers or drugs that affect the alpha adrenergic nervous system).9 There is good evidence to indicate that the baroreceptor reflex becomes less sensitive with age.28,41 As a result, the elderly could be more sensitive to the postural hypotensive effects of antihypertensive medications, with a consequent increased propensity for falls and fractures.14
Although some have argued that elderly persons with high blood pressure actually need higher blood pressure for adequate perfusion of vital organs (e.g., the brain and kidney),35 most studies have not shown that judicious use of antihypertensive medications in the elderly has a significant adverse effect on either renal or cerebral perfusion.12,55,68 It is clear from the work of Strandgaard that in middle-aged patients with chronic essential hypertension the pressure-flow curve for cerebral auto-regulation is reset to the right. The chronic hypertensive thus would be more susceptible to cerebral hypoperfusion if mean arterial pressure were lowered substantially and acutely.66 It is quite possible that a similar situation might exist in an elderly patient who had high blood pressure for a number of