Short-term heart rate variability during a cognitive challenge in young and older adults.

BACKGROUND attention-demanding tasks cause changes in the autonomic modulation of cardiac function. Heart rate variability, an index of autonomic modulation of heart rate, decreases with age. OBJECTIVE to examine heart rate variability in elderly and young participants at rest and during an attention-demanding task. METHODS we assessed 16 old participants (ages 72-91) and 16 college-age (ages 20-25) participants for short-term (5 min) heart rate variability at rest and during a simple-reaction time task. We report heart rate variability as the standard deviation of all interbeat intervals, and as the relative contribution of changes occurring at low- and high-frequencies. RESULTS there were no group differences in resting heart rate. A 2x2 mixed model ANOVA suggested a main effect of age on standard deviation of all interbeat intervals (P<0.05) which was significantly lower for the older group than their younger counterparts. There was also a significant effect of the test condition on standard deviation of all interbeat intervals and spectral measures of heart rate variability (P<0.05) in that standard deviation of all interbeat intervals dropped during the simple reaction time as did high-frequencies, while normalized low frequency power increased. CONCLUSION cardiac autonomic modulation during provocative stress show similar physiologic responses in young and older adults.