Hypertension in the elderly: epidemiology and pathophysiology.

In all but a few remote and unacculturated tribes, blood pressure rises with advancing age. By the time Western adult males or females reach their 70s their probability of being hypertensive (BP greater than 140/90 mmHg) exceeds 50%. Unlike various other risk factors for vascular disease, hypertension retains its predictive power as age increases, but since the baseline risk is higher, the number of cases of disease attributable to hypertension is much higher in the elderly than in the young. The reason for the rise in blood pressure with aging is not well established, although a high lifetime intake of sodium may be a contributing factor. It now appears that the major hemodynamic abnormality is an increased peripheral resistance. It is possible that an accentuation of changes that take place with normal aging might be responsible for this phenomenon. They include a reduction in renal function, decreased baroreceptor sensitivity, or increased sympathetic activity. Up until the present time studies have been unable to isolate the mechanisms involved.