Age-dependent cardiorespiratory directional coupling in wake-resting state.

Area of Science:

• Physiology
• Cardiorespiratory Interactions
• Aging Research

Background:

• Cardiorespiratory system cooperation is vital for maintaining internal stability.
• Previous studies on system interactions often used limited physiological states like sleep.
• Quantifying the influence between cardiorespiratory systems has been challenging.

Purpose of the Study:

• To investigate cardiorespiratory directional coupling in young and elderly adults during a wake-resting state.
• To quantify the strength and direction of interactions between the cardiac and respiratory systems across age groups.
• To explore how ageing affects autonomic modulation influencing cardiorespiratory coupling.

Main Methods:

• Calculated the directionality index (DI) using instantaneous phases from heartbeat interval and respiratory signals.
• Assessed influence from the cardiac to respiratory system (nc_r) and vice versa (nc_c).
• Compared DI, nc_r, and nc_c values between young (n=20) and elderly (n=19) subjects.

Main Results:

• Significantly lower DI values were observed in the elderly group (-0.17) compared to the young group (-0.52) (p<0.001).
• Both nc_r and nc_c showed significant differences between the age groups (p<0.001).
• These findings indicate age-related alterations in the bidirectional influence between cardiac and respiratory systems.

Conclusions:

• Ageing significantly alters cardiorespiratory directional coupling, affecting both cardiac-to-respiratory and respiratory-to-cardiac influences.
• Observed changes may be linked to age-associated differences in autonomic nervous system modulation.
• The developed quantitative approach can track system interactions and inform understanding of physiological dysfunctions.