Autonomic cardiovascular responses in old age

The effect of age on autonomically mediated cardiovascular responses to certain manoeuvres was studied in 15, healthy, old men and women (60-80 years). The results were compared with groups of healthy young (about 25 years) and middle-aged (about 45 years) subjects. There was no significant reduction in cardiovascular responses between the young and middle-aged groups. Respiratory sinus arrhythmia, and heart rate, blood-pressure and contralateral forearm blood flow increases to isometric hand grip, as well as the heart rate decrease during a dive reflex test, were significantly attenuated in the old age group. The Valsalva ratio, and the heart rate and blood-pressure changes during an 8 min orthostatic test did not differ between the old and the two younger age groups. There seems to be only a moderate attenuation of autonomic cardiovascular responses to about 60 years, after which there is a more rapid decline. The difference in reduction between different responses, even those mediated by the same type of autonomic nerve, suggests that the decreased responses are not due to an isolated impaired function of the peripheral autonomic nerve. The impairment may be due to the receptor organ or a combination of defects in function of several parts of the autonomic nervous system in old age.