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

Background: attention-demanding tasks cause changes in die 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 2 x 2 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.