Gene × Environment contributions to autonomic stress reactivity in youth

Autonomic nervous system responses to social stimuli among autistic individuals: A systematic review and meta-analysis

Physiological responses to environmental and social stimuli have been studied broadly in relation to psychological states and processes. This may be especially important regarding autistic individuals, who show disparities in social interactions. However, findings from studies assessing autonomic nervous system (ANS) responses of autistic individuals present contradictions, with reports showing both autonomic disparities and intact autonomic functioning. The current study aimed to review the existing literature and to estimate if there is a difference between autistic individuals and neurotypical (NT) individuals in their autonomic responses to social stimuli. Furthermore, the study examined factors that may moderate this difference, including the type of physiological function measured, the level of participation required, as well as the age and intellectual functioning of the participants. The meta-analysis revealed a small and statistically insignificant overall difference between autistic and NT individuals, albeit with high heterogeneity. A further nested moderator analysis revealed a significant difference between autistic and NT individuals in physiological response that reflects mainly a parasympathetic nervous system (PNS) activity. Another difference was found in physiological response that reflects a combined activity of the sympathetic and parasympathetic systems, but only for experimental tasks that demanded active participation in social interactions. These results suggest a distinctiveness in autonomic regulation of autistic individuals in social situations, and point to the PNS as an important study objective for future investigation.

Early life adversity and cardiovascular responses to repeated stress among adolescents: Moderating role of COMT gene rs4680 polymorphism

BACKGROUND

Early life adversity (ELA) increases the risk of cardiovascular diseases through dysregulation of cardiovascular stress responses manifested by either exaggerated or blunted reactivity. The catechol-O-methyltransferase (COMT) gene rs4680 polymorphism has been identified in gene-environment interaction (G×E) studies to explain individual differences in the effects of ELA on physiological stress responses. However, little is known about whether ELA interacts with COMT gene rs4680 polymorphism to affect cardiovascular responses to repeated stress exposures.

OBJECTIVE

The current study examined the associations between ELA and cardiovascular responses to repeated stress exposures, and the moderating role of COMT rs4680 polymorphism in these associations.

METHODS

The childhood trauma questionnaire (CTQ) was administered to 359 junior school students who underwent a two-successive stress exposures protocol with continuous cardiovascular monitoring [heart rate (HR) and systolic and diastolic blood pressure (SBP, DBP)] across four laboratory phases, and their saliva samples for deoxyribonucleic acid (DNA) genotyping were collected.

RESULTS

ELA was associated with blunted HR reactivity to the first and second stress exposures, blunted SBP reactivity to the first stress exposure, and attenuated SBP habituation to repeated stress exposures. Moreover, COMT rs4680 moderated these associations, such that the associations between ELA and blunted HR, SBP, and DBP reactivity to the first stress and disrupted DBP habituation to repeated stress exposures only existed in GA/AA genotype carriers but not in GG genotype carriers.

CONCLUSIONS

These findings suggest that the A allele of COMT rs4680 is vulnerable to the negative effects of ELA on the developmental dysregulation of stress physiological systems.

Resting Heart Rate Mediates the Relationship between Parenting Style and Callous-Unemotional Traits in Chinese Children

Despite increasing knowledge of social and biological risk factors for callous-unemotional (CU) traits, relatively less is known about how these two sets of risk factors combine to affect these traits. The current longitudinal study investigated pathways from parenting style to CU traits via resting heart rate in a three-year project. Parents of 382 children completed the Parenting Styles and Dimensions Questionnaire at Time 1 (children Mean age = 9.06, SD = 0.94, range = 7-11 years), with the heart rate data collected at Time 2 (M = 10.16, SD = 0.93, range = 8-13 years) and CU traits assessed at Time 3 (M = 11.06, SD = 0.94, range = 9-13 years). We found that parenting style and CU traits were associated with resting heart rate, and that structural equation modeling showed resting heart rate to partially mediate the effect of parenting style on CU traits. Specifically, higher levels of authoritarian parenting were associated with lower resting heart rate, which in turn was linked to higher level of CU traits. On the contrary, children in the context of authoritative parenting showed relatively higher resting heart rate, which was predictive of lower CU traits. Overall, findings have implications for understanding the etiology of CU traits in children and developing effective prevention programs for children with affective deficits.

Life events are associated with elevated heart rate and reduced heart complexity to acute psychological stress

The current study examined whether the exposure to life events and reported impact of life events are associated with altered cardiac reactivity to an acute psychological stressor. Participants (N = 69) completed the Life Experience Survey (LES) and Positive and Negative Affect Schedule (PANAS) and undertook a standardized social-evaluative stress task. Cardiac activity was measured via heart rate and non-linear heart rate variability (HRV) indices Sample Entropy, SD1, SD2 and SD1/SD2 ratio. Heart rate and non-linear HRV were measured before, during and after stress exposure. Findings suggest higher heart rate reactivity in individuals reporting higher number and impact of negative and total life events. Decreases in Sample Entropy were evident for number as well as impact of life events. No associations were found for SD1, SD2 and SD1/SD2 ratio. Findings suggest that life-events are associated with elevated heart rate and diminished heart rate complexity in response to acute stress.

Early childhood psychosocial family risks and cumulative dopaminergic sensitizing score: Links to behavior problems in U.S. 9-year-olds

BACKGROUND

We examined, (a) whether in early childhood exposure to risky family environment in different domains (socioeconomic, mental, parenting practices, health behavior, and child-related risks) and accumulatively across various domains (cumulative risk) is associated with child's problem behavior at age 9, and (b) whether the association is more pronounced in children carrying cumulative dopaminergic sensitizing genotype or living in low-income families.

METHODS

Participants were 2,860 9-year old children (48% females; 48% Black) and their mothers from the 'Fragile Families and Child Wellbeing Study', a probability birth cohort from large U.S. cities. Mothers responded to questions on child's problem behavior (CBCL). Children responded to questions about their vandalism and substance use.

RESULTS

Cumulative family risk was associated with higher internalizing and externalizing behavior and higher vandalism and substance use. All domain-specific risk clusters were associated with higher internalizing behavior and, with the exception of child-related risk, with higher externalizing behavior. Mental health risks, risky parenting practices, and risky health behavior were associated with higher vandalism. Risky parenting practices were associated with higher substance use. The associations were robust to adjustment for cumulative dopaminergic sensitizing genotype. No G x E interactions with dopaminergic genotype and family SES were observed.

LIMITATIONS

Sample size was relatively small for genetic analysis and polygenic risk scores were not available.

CONCLUSIONS

Exposure to cumulative psychosocial family risks from early childhood is associated with early indicators of problem behavior in adolescence.

Neighborhood crime risk and resting respiratory sinus arrhythmia in middle childhood: Evidence of gender differences

Although there is a robust link between resting respiratory sinus arrhythmia (RSA), a biological marker of emotion regulation, and risk for psychopathology, the factors that may be associated with aberrant RSA development remain unclear. The goal of the current study was to examine the relation between children's resting levels of RSA and neighborhood crime, a macro-level environmental stressor associated with increased risk for multiple forms of psychopathology in youth. The levels of neighborhood crime were obtained using a geocoded neighborhood crime exposure database, allowing for the objective assessment of the likelihood of crime occurring in the child's community. The results indicated that the relation between neighborhood crime and resting RSA differed for girls and boys such that living in a neighborhood with higher risk of exposure to violent crimes was associated with lower RSA for girls, but not boys. These results suggest that living in a higher crime neighborhood is associated with an objective, biologically-based marker of emotion regulation and highlight how neighborhood crime may be specifically associated with risk for girls.

Associations of genetics, behaviors, and life course circumstances with a novel aging and healthspan measure: Evidence from the Health and Retirement Study

BACKGROUND

An individual's rate of aging directly influences his/her susceptibility to morbidity and mortality. Thus, quantifying aging and disentangling how various factors coalesce to produce between-person differences in the rate of aging, have important implications for potential interventions. We recently developed and validated a novel multi-system-based aging measure, Phenotypic Age (PhenoAge), which has been shown to capture mortality and morbidity risk in the full US population and diverse subpopulations. The aim of this study was to evaluate associations between PhenoAge and a comprehensive set of factors, including genetic scores, childhood and adulthood circumstances, and health behaviors, to determine the relative contributions of these factors to variance in this aging measure.

METHODS AND FINDINGS

Based on data from 2,339 adults (aged 51+ years, mean age 69.4 years, 56% female, and 93.9% non-Hispanic white) from the US Health and Retirement Study, we calculated PhenoAge and evaluated the multivariable associations for a comprehensive set of factors using 2 innovative approaches-Shapley value decomposition (the Shapley approach hereafter) and hierarchical clustering. The Shapley approach revealed that together all 11 study domains (4 childhood and adulthood circumstances domains, 5 polygenic score [PGS] domains, and 1 behavior domain, and 1 demographic domain) accounted for 29.2% (bootstrap standard error = 0.003) of variance in PhenoAge after adjustment for chronological age. Behaviors exhibited the greatest contribution to PhenoAge (9.2%), closely followed by adulthood adversity, which was suggested to contribute 9.0% of the variance in PhenoAge. Collectively, the PGSs contributed 3.8% of the variance in PhenoAge (after accounting for chronological age). Next, using hierarchical clustering, we identified 6 distinct subpopulations based on the 4 childhood and adulthood circumstances domains. Two of these subpopulations stood out as disadvantaged, exhibiting significantly higher PhenoAges on average. Finally, we observed a significant gene-by-environment interaction between a previously validated PGS for coronary artery disease and the seemingly most disadvantaged subpopulation, suggesting a multiplicative effect of adverse life course circumstances coupled with genetic risk on phenotypic aging. The main limitations of this study were the retrospective nature of self-reported circumstances, leading to possible recall biases, and the unrepresentative racial/ethnic makeup of the population.

CONCLUSIONS

In a sample of US older adults, genetic, behavioral, and socioenvironmental circumstances during childhood and adulthood account for about 30% of differences in phenotypic aging. Our results also suggest that the detrimental effects of disadvantaged life course circumstances for health and aging may be further exacerbated among persons with genetic predisposition to coronary artery disease. Finally, our finding that behaviors had the largest contribution to PhenoAge highlights a potential policy target. Nevertheless, further validation of these findings and identification of causal links are greatly needed.

Vagal Tone as a Putative Mechanism for Pragmatic Competence: An Investigation of Carriers of the FMR1 Premutation

Pragmatic language skills exist across a continuum in typical and clinical populations, and are impaired in many neurodevelopmental disorders, most notably autism. The mechanisms underlying pragmatic impairment are poorly understood, although theory suggests dampened vagal tone plays a role. This study investigated the FMR1 premutation as a genetic model that may lend insight into the relationship between vagal function and pragmatic ability. Participants included 38 women with the FMR1 premutation and 23 controls. Vagal tone accounted for significant variance in pragmatics across both groups and statistically mediated the effect of FMR1 premutation status on pragmatic ability. Results support vagal tone as a biophysiological correlate of pragmatic ability, which informs potential mechanistic underpinnings and could have implications for targeted treatment.

Developmental Adaptation to Stress: An Evolutionary Perspective

The assumption that early stress leads to dysregulation and impairment is widespread in developmental science and informs prevailing models (e.g., toxic stress). An alternative evolutionary–developmental approach, which complements the standard emphasis on dysregulation, proposes that early stress may prompt the development of costly but adaptive strategies that promote survival and reproduction under adverse conditions. In this review, we survey this growing theoretical and empirical literature, highlighting recent developments and outstanding questions. We review concepts of adaptive plasticity and conditional adaptation, introduce the life history framework and the adaptive calibration model, and consider how physiological stress response systems and related neuroendocrine processes may function as plasticity mechanisms. We then address the evolution of individual differences in susceptibility to the environment, which engenders systematic person–environment interactions in the effects of stress on development. Finally, we discuss stress-mediated regulation of pubertal development as a case study of how an evolutionary–developmental approach can foster theoretical integration.