Suchergebnisse

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.

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, 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. Birth weight 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 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 transcription factor binding sites, was associated with birth weight. These findings suggest that prenatal stress exposure impacts development via epigenetic changes in HPA axis genes.

BACKGROUND: The BDNF gene codes for brain-derived neurotrophic factor, a growth factor involved in neural development, cell differentiation, and synaptic plasticity. Present in both the brain and periphery, BDNF plays critical roles throughout the body and is essential for placental and fetal development. Rodent studies show that early life stress, including prenatal stress, broadly alters BDNF methylation, with presumed changes in gene expression. No studies have assessed prenatal exposure to maternal traumatic stress and BDNF methylation in humans. This study examined associations of prenatal exposure to maternal stress and BDNF methylation at CpG sites across the BDNF gene. RESULTS: Among 24 mothers and newborns in the eastern Democratic Republic of Congo, a region with extreme conflict and violence to women, maternal experiences of war trauma and chronic stress were associated with BDNF methylation in umbilical cord blood, placental tissue, and maternal venous blood. Associations of maternal stress and BDNF methylation showed high tissue specificity. The majority of significant associations were observed in putative transcription factor binding regions. CONCLUSIONS: This is the first study in humans to examine BDNF methylation in relation to prenatal exposure to maternal stress in three tissues simultaneously and the first in any mammalian species to report associations of prenatal stress and BDNF methylation in placental tissue. The findings add to the growing body of evidence highlighting the importance of considering epigenetic effects when examining the impacts of trauma and stress, not only for adults but also for offspring exposed via effects transmitted before birth.

AbstractThe 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.