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Exposure to stress early in life permanently shapes activity of the hypothalamic-pituitary-adrenocortical (HPA) axis and the brain. Prenatally, glucocorticoids pass through the placenta to the fetus with postnatal impacts on brain development, birth weight (BW), and HPA axis functioning. Little is known about the biological mechanisms by which prenatal stress affects postnatal functioning. This study addresses this gap by examining the effect of chronic stress and traumatic war-related stress on epigenetic changes in four key genes regulating the HPA axis in neonatal cord blood, placenta, and maternal blood: "CRH," "CRHBP," "NR3C1," and "FKBP5." Participants were 24 mother-newborn dyads in the conflict-ridden region of the eastern Democratic Republic of Congo. BW data were collected at delivery and maternal interviews were conducted to assess culturally relevant chronic and war-related stressors. Chronic stress and war trauma had widespread effects on HPA axis gene methylation, with significant effects observed at transcription factor binding (TFB) sites in all target genes tested. Some changes in methylation were unique to chronic or war stress, whereas others were observed across both stressor types. Moreover, stress exposures impacted maternal and fetal tissues differently, supporting theoretical models that stress impacts vary according to life phase. Methylation in several "NR3C1" and "CRH" CpG sites, all located at TFB sites, was associated with BW. These findings suggest that prenatal stress exposure impacts development via epigenetic changes in HPA axis genes.

The relation among children's evening activities, behavioral characteristics, and activity of the hypothalamic-pituitary-adrenocortical axis was assessed in normally developing children ages 7 to 10 years. Salivary cortisol at bedtime was compared on evenings when children had structured activities outside of the home with unstructured evenings at home in relation to parental reports of children's behavioral characteristics. Participating in evening activities, particularly sport activities, was associated with small increases in bedtime cortisol levels in boys but not in girls. Differences in cortisol on activity versus no-activity nights were negatively related to children's social isolation. These results show that in studies with children, nights on which participants engage in sport activities should be avoided when collecting ambulatory measures of salivary cortisol concentrations.

Objectives Early life stress is known to have enduring biological effects, particularly with respect to health. Epigenetic modifications, such as DNA methylation, are a possible mechanism to mediate the biological effect of stress. We previously found correlations between maternal stress, newborn birthweight, and genome-wide measures of DNA methylation. Here we investigate ten genes related to the methylation/demethylation complex in order to better understand the impact of stress on health. Materials and methods DNA methylation and genetic variants at methylation/demethylation genes were assayed. Mean methylation measures were constructed for each gene and tested, in addition to genetic variants, for association with maternal stress measures based on interview and survey data (chronic stress and war trauma), maternal venous, and newborn cord genome-wide mean methylation (GMM), and birthweight. Results After cell type correction, we found multiple pairwise associations between war trauma, maternal GMM, maternal methylation at DNMT1, DNMT3A, TET3, and MBD2, and birthweight. Conclusions The association of maternal GMM and maternal methylation at DNMT1, DNMT3A, TET3, and MBD2 is consistent with the role of these genes in establishing, maintaining and altering genome-wide methylation patterns, in some cases in response to stress. DNMT1 produces one of the primary enzymes that reproduces methylation patterns during DNA replication. DNMT3A and TET3 have been implicated in genome-wide hypomethylation in response to glucocorticoid hormones. Although we cannot determine the directionality of the genic and genome-wide changes in methylation, our results suggest that altered methylation of specific methylation genes may be part of the molecular mechanism underlying the human biological response to stress. [ABSTRACT FROM AUTHOR]

Comorbidity of internalizing and externalizing problems and its risk and protective factors have not been well incorporated into developmental research, especially among racial minority youth from high-poverty neighborhoods. The present study identified a latent comorbid factor as well as specific factors underlying internalizing and externalizing problems among 592 African American adolescents living in economically disadvantaged neighborhoods (291 male; M age = 15.9 years, SD = 1.43 years). Stressful life events and racial discrimination were associated with higher comorbid problems, whereas stressful life events and exposure to violence were associated with higher specific externalizing problems. Collective efficacy was associated with both lower specific externalizing problems and lower comorbid problems. Moreover, high collective efficacy buffered the risk effects of stressful life events and racial discrimination on comorbid problems. Our results demonstrated the advantages of latent variable modeling to understanding comorbidity by articulating impacts of risk factors on comorbid and specific components underlying internalizing and externalizing problems. They also highlighted the protective effect of collective efficacy in mitigating risks for these problems. These findings broadly call for more studies on comorbidities in developmental psychopathology among youth from diverse sociocultural backgrounds. [ABSTRACT FROM AUTHOR]

The present study tested whether pet dogs have stress-buffering effects for children during a validated laboratory-based protocol, the Trier Social Stress Test for Children (TSST-C). Participants were 101 children aged 7-12 years with their primary caregivers and pet dogs. Children were randomly assigned in the TSST-C to a pet present condition or one of two comparison conditions: parent present or no support figure present. Baseline, response, and recovery indices of perceived stress and cortisol levels were computed based on children's self-reported feelings of stress and salivary cortisol. Results indicated that in the alone (no social support) condition, children showed the expected rise for both perceived stress and cortisol response to stress. Pet dog presence significantly buffered the perceived stress response in comparison to children in the alone and parent present conditions. No main condition effect was observed for cortisol; however, for children experiencing the stressor with their pet present, lower cortisol response to stress was associated with more child-initiated petting and less dog proximity-seeking behavior. The results support the notion that pet dogs can provide socio-emotional benefits for children via stress buffering. [ABSTRACT FROM AUTHOR]

This study examined the effects of racial discrimination, community violence, and stressful life events on internalizing problems among African American youth from high-poverty neighborhoods ( N = 607; 293 boys; Mage = 16.0 years, SD = 1.44 years). Mediated effects via externalizing problems on these relations were also examined, given the high comorbidity rate between internalizing and externalizing problems. Externalizing problems partially mediated the effect of stressful life events on internalizing problems and fully mediated the effect of racial discrimination for boys but not for girls. Exposure to violence had a significant indirect effect on internalizing problems via externalizing problems. The findings call for greater attention to internalizing problems among African American youth and pathways to internalizing problems via externalizing problems. [ABSTRACT FROM AUTHOR]