Exacerbated Psycho‐physiological Response to Mild Stress Exposure in Middle‐aged People
Authors: Blons Estelle , Lespinet‐Najib Veronique , Gilfriche Pierre , Arsac Laurent M. , Grivel Eric , Deschodt‐Arsac Veronique 
Published: June 2021

Psychological stress is defined by a cognitive process in which a person takes into account his environment threats and challenges. Recently, it has been shown that non‐linear measures of heart rate dynamics can be used as a biomarker of the integrated functioning of the brain, based on an identified interconnected network1. The complexity indices calculated from non‐linear analyses capture the full depth of physiological signal output, thereby providing meaningful insights on the heart brain interactions. The higher the complexity, the higher the capacity to adapt to an ever‐changing environment, both being degraded in elderly people. Here, we assessed complexity (entropy) in cardiac dynamics in young vs. middle‐aged people challenged by cognitive tasks with or without stress exposure, in order to reveal early stages of age‐related defects.

Young (n=25, 27.8 ± 7.8 years) and middle‐aged (n=14, 53.8 ± 4.6 years) people participated in the study. Heart inter‐beat (RR) time series were obtained in rest condition, and when performing two series of cognitive tasks: without stress (CT) or with mild induced stress (SCT). The stress was induced by negative visual feedbacks, time pressure, sound disturbances and an inattentive audience. RR intervals were recorded (Polar belt) during 8 min in each situation. Multiscale Entropy (MSE)2 was computed on scales 1–3. The entropy index EI was derived by calculating the area under the curve produced by the calculation of sample entropy at each time scale. Participants filled out a series of questionnaires online to assess anxiety and workload levels in each situation. Performance scores to cognitive tasks were also obtained in CT and SCT.

In response to CT, both workload and entropy index (EI) increased for both young and middle‐aged people (workload: respectively +102.6 ± 77.5 % and +158.3 ± 145.4 %, P<0.001, EI: +9.9 ± 18.3 % and +15.8 ± 18.7 %, P<0.05). When a mild stress was induced (SCT), middle‐aged showed decreased performance scores (−23.2 ± 22.9 %, P=0.002), higher anxiety (+27.0 ± 20.8 %, P=0.001) and lower EI (−8.2 ± 9.8 %, P=0.048), compared to CT. No such changes were observed in young.

The present study shows interesting new findings. Complexity in cardiac dynamics increased during the cognitive tasks likely underlying an improved multiscale coordination in heart brain interactions. This enhancement may be disrupted under stress exposure for middle‐aged but not for young people, possibly due to an altered amygdala‐prefrontal circuitry3. This lack of physiological complexity in heart rate dynamics, associated with an increased anxiety, reveals an age‐related sensitivity to mild stress exposure. The present results show significant added value in combining non‐linear analyses with psychological assessments, to evaluate psycho‐physiological impairments highlighted by stress exposure.

This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.