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The present study aimed to provide further evidence on the usefulness of non-linear cardiac measures when examining the output of the cardiac system. Scale-invariant self-similarity and entropy, in addition to heart rate variability (HRV) given by time- and frequency-domain measures were calculated in a sample of N = 55 healthy adolescents (Mage = 14.122, SDage = 0.698) during 10-min positive (non-stressful) and negative (stressful) interactions with their mothers. We also explored sex influence in adolescents' cardiac output using both HRV measures and non-linear cardiac measures. Repeated measures MANOVA revealed a marginal within-group effect for HRV measures, F(3,51) = 2.438, p = 0.075, η2p = 0.125), and a significant within-group effect for non-linear cardiac measures, F(6, 48) = 3.296, p = 0.009, η2p = 0.292, showing a significant decrement in adolescents' cardiac complexity during the negative interaction. No significant effect for sex was found in either non-linear cardiac measures or HRV measures, but results suggest lower cardiac scaling in females than in males. These findings suggest a real-time scale predominance in heart rate output when adolescents face an aversive situation and support the importance of non-linear cardiac measures to gain insight into the cardiac system and its regulatory mechanisms. Further research is needed to examine sex-differences in cardiac complexity during aversive situations. [ABSTRACT FROM AUTHOR]

This paper aimed to (a) validate a novel technique that quantifies the length of the trajectories the cardiac system follows within a two-dimensional state-space, and (b) test its usefulness to better understand how cognitive emotion regulation (CER) style is associated with cardiac output. A positive CER style was assessed in a sample of healthy adolescents (n = 57), and mean and total distances, in addition to heart rate variability (HRV) measures and cardiac entropy (SampEn), were calculated during a conflict discussion with the adolescents' mothers. Associations between distances and HRV measures in timeand frequency-domains and SampEn were examined to better understand the physiological meaning of distances; further, whether a positive CER style would predict distances, HRV, and SampEn. Correlation analysis revealed that associations of distances with time-domain HRV measures were stronger than associations with frequency-domain HRV measures, while correlations between distances and SampEn were moderate. Hierarchical multiple regression analysis revealed that a positive CER style predicted distances and SampEn, but not HRV measures. Distances are clearly time-domain measures of HRV, but only partly capture the complexity of the heart signal. The results highlight the importance of assessing heart rate dynamics beyond HRV in the study of CER. [ABSTRACT FROM AUTHOR]

An inverted U-shaped pattern in heart rate (HR) and a U-shaped pattern in heart rate variability (HRV) are easily recognizable when individuals experience any acute stressor. How cardiac complexity (scaling and entropy) changes under acute stress is not well known. Psychologically, emotion regulation (ER) style is likely to influence the individual's specific behavioral response when c®·onting stress. This study tested whether adolescents with distinct ERstyles would show diffdrent patterns oflinear and nonlinear cardiac changes under stressful conditions. We predicted less autonomic jlexibility for adolescents with a highly negative emotional regulation (HNER) style (n = 10) than for those adolescents with a highly positive emotional regulation (HPER) style (n= 10). Further, associations between linear and nonlinear measures during each condition were examined for each group. Repeated measures ANOVAs revealed that HR and HRV changed according to the predicted pattern. Higuchi's fractal dimension and Sample Entropy followed a U-shaped pattern, whereas the short-term scaling exponent followed the reverse pattern. Cardiac changes across conditions were larger in the HPER group. SigniAcant associations between linear and nonlinear measures were /bund in the HPER group but not in the HNER group. Results are cautiously discussed within a multiscalefraniework offluctuations of the different cardiac feantres. [ABSTRACT FROM AUTHOR]

Background and Objectives: Negative cognitive emotion regulation (ER) strategies are particularly important within the framework of anxiety problems amongst youths and how they cope with stressful events. The aim of this study was to examine the associations between both negative and positive ER style and cardiac regulation under stressful conditions.Design: Eighty-nine adolescents (M = 13.31 years, SD = 0.68, 44.94% girls) were exposed to a socially relevant stress induction protocol.Methods: Participants' emotion regulation strategies were assessed and their cardiac function was recorded.Results: A negative ER style predicted heart rate (HR) entropy at the stressful stage after controlling for anxiety scores. In addition, heart rate variability reactivity and recovery and HR entropy recovery were larger (p < .05) in the low negative ER style group (n = 16) than in the high negative ER style group (n = 23).Conclusions: Results suggest that individuals with a highly negative ER style have diminished autonomic flexibility. [ABSTRACT FROM AUTHOR]

This paper introduces a new measure to evaluate heart output from a dynamical systems approach. The measure is based on the time delay technique for two-dimensional state space reconstruction from time series of interbeat intervals. The system's trajectories within this space are depicted and the mean distance, as well as the total and maximum distances travelled by the system, are calculated in pixels. Preliminary data from adolescents with highly positive emotional regulation (HPER) style (n=JO) and adolescents with highly negative (HNER) style (n= 10) who underwent a protocol of stress induction show the usefulness ofthe new metrics to distinguish the dynamical behavior of the heart systems from these groups. Repeated measures ANOVAs revealed that changes in all three distances across conditions (baseline. anticipation of stress. exposure to stress, and recovery) were significant in the HPER group but not in the HNER group. As to the physic, logical meaning of the new measure a correlational analysis revealed that associations with time-domain HRV measures were stronger than associations with frequency-domain HRV measures in both groups. Because of the small sample size, bootstrap resampling was used to obtain confidence intervals. Distances calculated with the new measure are sensitive to the ER-related cardiac flexibility under acute stress conditions. However, the physiological meaning of the new indices remains unclear. [ABSTRACT FROM AUTHOR]

Background: The association between decreased heart rate variability (HRV) and increased internalizing symptoms is well documented. Adolescence is a critical period for the development of mental health problems, in particular internalizing symptoms. Previous research has illustrated sex differences in adolescent HRV, such that females have reduced short-term resting state HRV compared to males. Studies on long-term ecological recordings of HRV in adolescents are scarce. The aims of the present study were, (a) to test if adolescent females show decreased long-term HRV and cardiac complexity (CC) compared to males, and (b) to explore whether sex and HRV and CC measures, as well as their interaction, would predict internalizing symptoms. Materials and Methods: HRV was recorded in n = 166 adolescents (86 girls), on a normal school day. HRV and CC measures were calculated on the interbeat interval time series. Results: Females showed lower HRV and CC in most of the assessed indices. Internalizing symptoms were mainly predicted by HRV whereas sex only predicted symptoms of social anxiety. The interaction between sex and HRV did not predict internalizing symptoms. Conclusions: Results suggest that reduced HRV should be considered as a potential contributor to exacerbating internalizing symptoms in adolescence. Girls with reduced HRV and CC might be prone to the development of internalizing disorders. HRV is a promising tool for the early identification of vulnerability. [ABSTRACT FROM AUTHOR]

The risk of suffering anxiety disorders is associated with sustained subthreshold symptoms of anxiety. This study evaluated the stability of anxiety scores (high, moderate or low) across a six-month period in early adolescents (N = 95). The associations between sustained anxiety, vagally-mediated heart rate variability (vmHRV), sympathetic activity, and heart rate fractal dynamics in everyday life conditions were analyzed. The anxiety scores from 71.50% of participants remained at the same level. The linear correlations between anxiety and cardiac measures were weak but a group-based approach revealed that the fractal dimension (FD) from stable-low anxiety participants was higher than the FD from participants with stable-moderate anxiety scores but not higher than the FD from the stable-high anxiety group. The short-term correlations’ exponent α1 from the stable-high anxiety group was higher than the α1 from the stable-moderate anxiety group but not higher than the exponent from the stablelow anxiety group. No differences were found in the vmHRV nor sympathetic activity. The lack of a direct association between the complexity of the heart rate and the level of sustained anxiety suggests a nonlinear pattern of associations that would be in accordance with the optimum variability principle. [ABSTRACT FROM AUTHOR]

Background and Objectives: Diminished heart rate variability has been found to be associated with high anxiety symptomatology. Since adolescence is the period of onset for many anxiety disorders, this study aimed to determine sex- and anxiety-related differences in heart rate variability and complexity in adolescents.Methods: We created four groups according to sex and anxiety symptomatology: high-anxiety girls (n = 24) and boys (n = 25), and low-anxiety girls (n = 22) and boys (n = 24) and recorded their cardiac function while they performed regular school activities. A series of two-way (sex and anxiety) MANOVAs were performed on time domain variability, frequency domain variability, and non-linear complexity.Results: We obtained no multivariate interaction effects between sex and anxiety, but highly anxious participants had lower heart rate variability than the low-anxiety group. Regarding sex, girls showed lower heart rate variability and complexity than boys.Conclusions: The results suggest that adolescent girls have a less flexible cardiac system that could be a marker of the girls' vulnerability to developing anxiety disorders. [ABSTRACT FROM AUTHOR]

Maladaptive patterns of cardiac adjustment to stress in adolescents may reveal their vulnerability to anxiety disorders (ADs). Traditional research in this field has focused on anxiety levels, whereas the time course of anxiety has rarely been considered. Nevertheless, since overall anxiety decreases as adolescence progresses, increasing time courses are clinically relevant and can be associated with maladaptive contextual adjustment. In this study, the cardiac pattern of adjustment to stress in adolescents with increasing anxiety was analysed. A sample of 44 adolescents ( M = 14.88 years, SD = 0.53, 45.45% boys) were exposed to a socially relevant stress induction protocol, and their cardiac functioning was recorded. Participants with a trajectory of increasing anxious symptomatology over a 12-month period ( n = 24) showed attenuated heart rate levels in the stage of maximum stress in comparison to their non-increasing anxious counterparts ( p < 0.05), as well as a heightened pattern of sample entropy throughout the stress induction ( p < 0.05). These findings suggest a loss of cardiac flexibility in those adolescents at risk of ADs when confronting an acute stressor. [ABSTRACT FROM AUTHOR]

Nonlinear measures can capture the complex structure of the heart beating, and recordings taken while the individual performs daily activities may help to understand the cardiac system's output in natural conditions. As healthy systems are characterized by having highly complex outputs, we hypothesized that the cardiac output from high anxious adolescents should be less complex than the output from their low anxious counterparts. In this study ECG was recorded for two hours in 50 adolescents while they performed regular school activities. Fractal dimension (FD), scaling exponents and multiscale entropy were calculated on the interbeat intervals time series. Both FD and entropy were significantly lower in the high-anxious group than the low-anxious group. These results suggest different heart-related regulation in adolescents who suffered from high anxious symptomatology. [ABSTRACT FROM AUTHOR]

Abstract: The present study explores both resting cortical EEG asymmetry and vagally-mediated heart rate variability (HRV), as an index for vagal tone, as physiological correlates of self-reported attentional control in a sample of 53 healthy young adults. Regression analyses indicate that higher vagally-mediated HRV and lower right-sided parietal activity in the β2 frequency range (20–30Hz) are significant predictors of larger attentional control. Results are in line with some of the basic features of the neurovisceral integration model and stress the role of parietal areas in attentional control capabilities, thus aiming to consider attentional control as a trait-like disposition. [Copyright &y& Elsevier]

This study tested the hypothesis that flight-phobic patients experience change at different rates even when they are receiving identical treatment. Faster within-session rates of change (WSRC) were expected for patients who required fewer exposure sessions. The study also tested the theoretical role of autonomic flexibility on WSRC. High flexibility should be associated with faster rates of change. Thirty-seven flight-phobic patients were successfully treated with a computer-assisted fear of flying treatment. A significant negative correlation was found between total number of sessions and WSRC: The fewer sessions patients attended, the faster their rate of change was. The role of autonomic flexibility was partially supported: A significant correlation between heart rate variability and WSRC revealed that flexible patients improved faster than less-flexible patients. © 2011 Wiley Periodicals, Inc. J Clin Psychol 67:1-11, 2011. [ABSTRACT FROM AUTHOR]

Background: Anxiety disorders frequently have an onset during adolescence, which when left untreated could lead to a chronic course and outcome. This study aimed to examine the way in which a cognitive behaviour therapy-based programme (Super Skills for Life - adolescent version; SSL-A) could change the course of anxiety symptoms through adolescent's behavioural performance and cardiac function.Method: Sixty-one adolescents at risk of developing an anxiety disorder (45.30% boys; M = 13.76 years, SD = 0.32) were randomly assigned to either an intervention (IG), placebo (PG), or a waitlist group (WG). Adolescents in the IG participated in SSL-A over an 8-week period. Adolescents in the PG participated in an 8-session school-work programme. Adolescents in the WG did not receive any intervention. Anxiety symptoms were assessed every six months, twice before the intervention, as well as at the post-intervention and six months after the intervention. Participants in the IG additionally underwent a stressful task to assess behavioural performance and cardiac adjustment.Results: Adolescents in the IG significantly reported lower levels of social phobia and generalised anxiety symptoms at the follow-up assessment compared to the adolescents in the PG and the WG. They also showed a significant improvement in vocal quality and lower discomfort during a stressful task at post-intervention, and showed attenuated cardiac recovery indexes, in terms of sample entropy.Limitations: The study has a small sample size.Conclusion: SSL-A changed the natural course of anxiety symptoms, as shown by a significant reduction in social phobia and generalised anxiety symptoms, and a significant improvement in behaviour and physiological (cardiac) function during a stressful situation. [ABSTRACT FROM AUTHOR]