Variabilidad neuroconductual y de la frecuencia cardiaca en adultos mayores sanos: efecto de la complejidad de la tarea

The increase in mental effort is inherent to natural aging. It induces an increase in the variability of the response speed and alteration of the variability of the heart rate. However, studies comparing these two sources of different variability are scarce and inconsistent. The objective of the present work was to describe the patterns of variability in response speed and heart rate during the execution of tasks with increasing demands of decisive difficulty in a group of older adults and healthy young controls, in addition to comparing both patterns of variability. In the present study 18 older adults over 60 years and 18 young people between 20 and 25 years were compared during the execution of tasks with increasing degree of difficulty. The net time of evaluation of the stimulus (central time) was isolated from the motor component. In parallel the electrocardiographic activity was recorded. The central time and indicators of heart rate variability were compared using ANOVAs. As a consequence of the increase in mental load, healthy older adults exhibited a multiplicative increase in psychomotor retardation, and gradual vagal control of the heart. In healthy older adults, the increase in complexity causes increased attention span and, consequently, variability, as well as a predominance of vagal control as an adaptive mechanism of regulation of the prefrontal cortex to environmental challenges.