Autonomic Reactivity and Adjustment in Middle Childhood

The primary aim of this study was to investigate whether the joint action of the parasympathetic (PNS) and sympathetic nervous system (SNS) influenced three distinct indicators of child adjustment. Although evidence suggests that patterns of reactivity in the PNS and SNS each contribute to adjustment in youth, a paucity of work has examined the interaction between the two systems. Moreover, much of the research on children\u27s autonomic reactivity has overly relied on variable-centered analytic approaches, which aim to predict variance and assume homogeneity in the relations between predictors and outcome. This project also incorporated a person-centered approach to systematically identify individual differences in the interrelation between PNS and SNS reactivity and to classify children into homogeneous autonomic reactivity groups. The person-centered results were then applied to variable-centered analyses to examine how adjustment varied across homogeneous autonomic reactivity groups. Thus, the goal of this study was to apply both variable-centered and person-centered analyses to investigate whether children\u27s autonomic reactivity was related to child adjustment. Children (N = 64, 8-10 years, M = 9.06, SD = 0.81) and one parent completed a psychophysiological laboratory assessment at Wave 1 during which each child\u27s respiratory sinus arrhythmia reactivity (RSAR; an index of PNS reactivity) and skin conductance level reactivity (SCLR; an index of SNS reactivity) was assessed in response to a mirror tracing challenge task. At both Wave 1 and Wave 2, each parent reported on their child\u27s internalizing symptoms, externalizing symptoms, and social competence. The variable-centered analyses revealed that, consistent with hypotheses, the two-way RSAR x SCLR interaction was significant predicting internalizing symptoms at Time 1 and at Time 2. In both cases, RSA withdrawal was associated with fewer internalizing symptoms when coupled with low SCLR. When coupled with high SCLR, RSA withdrawal was associated with more internalizing symptoms at Time 1; however, RSAR was unrelated to Time 2 internalizing when coupled with high SCLR. In addition, SCLR was associated with more social competence and (marginally) fewer externalizing problems over time. The person-centered analyses (i.e., a model-based cluster analysis) identified two distinct clusters based on children\u27s RSAR and SCLR. Children in Cluster 1 showed slight RSA withdrawal combined with SCL activation (modest reciprocal SNS activation) and exhibited marginally more internalizing and less social competence, as compared to children in Cluster 2 who, as a group, showed heightened RSAR (either withdrawal or augmentation) and SNS activation. When a 3-cluster model was examined, results indicated that children who showed modest reciprocal SNS activation (Cluster 1) showed marginally more internalizing symptoms then children who showed strong reciprocal SNS activation (Cluster 2A) and marginally less social competence then children who showed coactivation (Cluster 2B). This study offers important evidence that person-centered analyses can identify differences in autonomic reactivity that are relevant to children\u27s adjustment. Cluster analysis identified only two (i.e., reciprocal SNS activation, coactivation) of the four autonomic profiles assumed to be represented in simple slope analyses in previous work. Thus, incorporating person-centered techniques in future research is an important and likely fruitful approach to investigating how autonomic reactivity contributes to child development