Attenuated reactivity of salivary alpha-amylase has been proposed as a specific sympathetic marker of disruptive behavior in juveniles and may have additional value to studying other autonomic parameters and hypothalamic–pituitary–adrenal axis activity. Investigating the interrelationships between neurobiological parameters in relation to juvenile disruptive behavior may enhance insight into the complex mechanisms at play. We investigated salivary alpha-amylase, cortisol, heart rate (HR), and heart rate variability (HRV) in response to a standardized public speaking task, and examined interactions between these parameters in relation to disruptive behavior. Participants were 48 delinquent male adolescents (mean age 18.4years, SD 0.9), with and without a disruptive behavior disorder (resp. DP+, DP−) and 16 matched normal controls (NC). A structured psychiatric interview as well as the Youth Self Report and Child Behavior Checklist were administered to assess disruptive behavior. Alpha-amylase and cortisol reactivity, but not HR or HRV, showed significant inverse associations with dimensional measures of disruptive behavior. Moreover, both cortisol and alpha-amylase reactivity were significantly lower in the DP+ group as compared to the NC group. The mentioned relationships remained present when nicotine use was entered as a covariate. Combining alpha-amylase and cortisol in one model explained a larger part of the variance of disruptive behavior than either single parameter. There were no interactions between alpha-amylase and cortisol or HRV in relation to disruptive behavior. Attenuated alpha-amylase responsivity to stress is a correlate of disruptive behavior in late-adolescent males. Although nicotine use explains a considerable part of the variance of disruptive behavior, both alpha-amylase and cortisol are related to disruptive behavior, over and above the effect of nicotine use. Combining alpha-amylase and cortisol improved insight into neurobiological mechanisms involved with disruptive behavior; concurrent low reactivity of both parameters was related to higher levels of disruptive behavior.

Purpose
Autonomic nervous system (ANS) functioning has long been studied in relation to antisocial behaviour, but relevant measures (heart rate, heart rate variability, pre-ejection period, respiration rate) have rarely been considered together. This study investigated the relationship between these measures and antisocial behaviour.
Methods
Using a sample of 1010 youths with (47.8%) and without conduct disorder (52.2%) aged between 9 and 18years (659 females, 351 males, mean age=14.2years, SD=2.4), principal component analysis (PCA) was applied to various measures of psychopathology and antisocial behavior. Structural equation modelling was performed in order to test whether the ANS measures predicted PCA-dimensions. Cluster analysis was used in order to classify patterns of ANS activity. Analyses were performed separately for males/females and controlled for body-mass-index, age, caffeine use, cigarette smoking, sports, socioeconomic status, medication, cardiac problems.
Results
The PCA yielded three components: antisocial behaviour/comorbid psychopathology, narcissistic traits, and callous-unemotional traits. ANS measures were only weakly correlated with these components. Cluster analysis yielded high and low arousal clusters in both sexes. When controlling for covariates, all associations disappeared.
Conclusion
Our findings suggest that resting ANS measures are only weakly related to antisocial behaviour and indicate that smoking should be considered as an important covariate in future psychophysiological studies.

Purpose
Autonomic nervous system (ANS) functioning has been widely studied in relation to antisocial behavior, such as Conduct Disorder (CD). However, research in females is scarce and findings are inconsistent. This study investigated baseline ANS activity in CD children and adolescents and tested for sex differences. Furthermore, subgroups of CD were investigated: +/‐ Limited Prosocial Emotions (LPE), +/‐ comorbid internalizing disorders (INT).
Methods
Baseline ANS activity was measured by Heart Rate (HR), Heart Rate Variability (HRV; parasympathetic activity), Pre-Ejection Period (PEP; sympathetic activity), and Respiration Rate (RR). 659 females (296 CD, 363 controls) and 351 males (187 CD, 164 controls), aged 9–18 years participated.
Results
Baseline HR, HRV and PEP did not differ between CD subjects and controls in both sexes. RR was higher in CD participants than controls amongst females, but not males. LPE was unrelated to ANS activity, whereas females with CD + INT presented lower HRV.
Conclusions
These results suggest that baseline ANS activity is not a robust indicator for CD. However, deviant ANS activity – especially parasympathetic activity – was observed in CD females with internalizing comorbidity. The psychophysiological abnormalities observed in this subgroup are indicative of emotion regulation problems. Accordingly, this subgroup may require specific interventions.

Reduced responsiveness to emotions is hypothesized to contribute to the development of conduct disorder (CD) in children and adolescents. Accordingly, blunted psychophysiological responses to emotions have been observed in boys with CD, but this has never been tested in girls. Therefore, this study compared psychophysiological responses to sadness in girls and boys with and without CD, and different clinical phenotypes of CD: with versus without limited prosocial emotions (LPE), and with versus without comorbid internalizing disorders (INT). Nine-hundred and 27 girls (427 CD, 500 controls) and 519 boys (266 CD, 253 controls) aged 9–18 years participated. Psychophysiological responses were measured while participants watched two validated sad film clips, specifically: heart rate (HR), respiratory sinus arrhythmia (RSA; indexing parasympathetic activity), preejection period (PEP; indexing sympathetic activity). Girls and boys with CD showed larger HR responses to sadness than controls. This effect was rendered nonsignificant, however, after controlling for covariates. We observed aberrant RSA responses to sadness in CD compared with controls. Similarly, we found a significant positive association between RSA responsivity and antisocial behavior when assessed dimensionally. The effects were very small, though. Results were similar for boys and girls. We found no evidence for emotional underresponsiveness in CD in the largest psychophysiological study to date in this field. More research is needed to explore whether this is specific to sadness or generalizes to other emotions. Furthermore, we recommend that studies on emotion processing in CD assess different physiological measures to help disentangle CD-related effects on sympathetic and parasympathetic activity. (PsycInfo Database Record (c) 2022 APA, all rights reserved)