The population's aging underscores the need to understand the process and define the physiologic markers predictive of healthy longevity. The findings that aging is associated with a progressive decrease in heart rate variability (HRV), an index of autonomic function, suggests that longevity might depend on preservation of autonomic function. However, little is known about late life changes. We assessed the relation between autonomic function and longevity by a cross-sectional study of HRV of 344 healthy subjects, 10 to 99 years old. The HRV was determined from 24-hour Holter records, using 4 time domain measures of HRV (the root mean square of the successive normal sinus RR interval difference [rMSSD], percentage of successive normal sinus RR intervals >50 ms [pNN50], standard deviation of all normal sinus RR intervals during a 24-hour period [SDNN], and standard deviation of the averaged normal sinus RR intervals for all 5-minute segments [SDANN]). Autonomic modulation of the 4 measures differs, permitting distinctions between changes in HRV-parasympathetic function, using rMSSD and pNN50, and HRV-sympathetic function using SDNN and SDANN. Decade values were compared using analysis of variance and t-multiple comparison testing. The HRV of all measures decreases rapidly from the second to fifth decades. It then slows. The HRV-sympathetic function continues to decrease throughout life. In contrast, the decrease in HRV-parasympathetic function reaches its nadir in the eighth decade, followed by reversal and a progressive increase to higher levels (p <0.05), more characteristic of a younger population. In conclusion, healthy longevity depends on preservation of autonomic function, in particular, HRV-parasympathetic function, despite the early age-related decrease. The eighth decade reversal of the decrease in HRV-parasympathetic function and its subsequent increase are key determinants of longevity. Persistently high HRV in the elderly represents a marker predictive of longevity.
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