Negative family expressiveness and adolescents' externalizing problems: Respiratory sinus arrhythmia as a moderator and anger regulation as a mediator.

Family environment, emotion regulation and biological sensitivity have been shown to be associated with adolescents' externalizing problem behaviours. However, findings regarding respiratory sinus arrhythmia (RSA) reactivity are mixed and sometimes contradictory. This study aims to clarify the roles of RSA reactivity and anger regulation in the relationship between negative family expressiveness (NFE) and adolescents' externalizing behaviour by measuring RSA reactivity during the Parent-Adolescent Interaction Task (PAIT), designed to simulate a naturalistic negative family environment. In this study, 125 Chinese adolescents (M = 13.95 years, SD = 0.95; 48% male) completed questionnaires assessing negative family expressiveness, anger regulation and externalizing problems. Additionally, we collected electrocardiogram and respiration data during both the resting period and a 10-min PAIT. Results showed that anger regulation mediated the relationship between NFE and externalizing problem behaviours. Moreover, adolescents' RSA reactivity moderated this mediation effect, even after controlling for baseline RSA. Greater RSA suppression potentially indicated greater susceptibility, with the relationship between NFE and anger regulation being more pronounced in adolescents with greater RSA suppression compared to those with lesser RSA suppression. These findings highlight the importance of considering physiological systems, especially within the context of adverse family environments, when studying the relationships with externalizing problems.

Maternal postnatal depressive symptoms and children's internalizing problems: The moderating role of mother-infant RSA synchrony.

Maternal depressive symptoms are a crucial risk factor for children's internalizing problems, though positive mother-child relationships may buffer this risk transmission. Mother-child physiological coregulation (e.g., synchrony) has emerged as a potentially important mechanism of developmental psychopathology and may play a role in the transmission of internalizing symptoms. In this two-wave longitudinal study, we examined whether and how mother-infant physiological synchrony (of respiratory sinus arrhythmia; RSA) moderated the association between maternal postnatal depressive symptoms and children's internalizing problems in a rural, low-SES community sample (N = 166 dyads). At 6 months, mother-infant RSA synchrony and infant negative affect were assessed during free play. Mother reported their depressive symptoms at 6 months and children's internalizing problems at 24 months. Multilevel structural equation models indicated that mother-infant dyads demonstrated significant and positive RSA synchrony on average and RSA synchrony significantly moderated the association between maternal depressive symptoms and children's internalizing problems even after controlling for infant negative affect. Greater maternal depressive symptoms were associated with higher child internalizing problems when RSA synchrony was lower but not when it was higher. This finding suggests that mother-infant RSA synchrony may operate as a resilience factor for the intergenerational transmission of internalizing symptoms in community samples.

Breastfeeding duration and vagal regulation of infants and mothers.

BACKGROUND: Vagal regulation within the parasympathetic nervous system supports self-regulation and social engagement. Research has suggested that early feeding practices may influence mother-infant vagal functioning. AIM: We aimed to examine the association between breastfeeding duration and mother-infant vagal regulation during an interaction. We hypothesized that breastfeeding duration would be positively associated with adaptive vagal regulation in infants and mothers. METHOD: 204 mother-infant dyads (infant mean age 6 months) completed the face-to-face still-face (FFSF) task. During the task, vagal regulation indexed by respiratory sinus arrhythmia (RSA, a component of heart rate variability) was calculated through continuously recorded electrocardiogram signals. Breastfeeding duration and demographic information were reported by mothers. Linear mixed models were adopted to estimate the associations between breastfeeding duration and repeated measures of RSA in infants and mothers throughout the FFSF. RESULTS: Infants breastfed for a longer duration demonstrated lower RSA throughout the FFSF (B = -0.06, 95 % CI: -0.09 to -0.03), suggesting active physiological mobilization to engage in interaction and regulate distress. Mothers with longer breastfeeding duration displayed higher baseline RSA and higher overall RSA levels (higher vagal control) during the FFSF (B = 0.06, 95 % CI: 0.02 to 0.09), indicating a calmer and regulated state. CONCLUSION: Longer breastfeeding duration was associated with more adaptive mother-infant vagal regulation during the interaction, indicating a positive dose-response association. This finding reveals breastfeeding practice as a factor contributing to infant effective vagal regulation and further supports WHO recommendation on exclusive breastfeeding for the first 6 months and continuing breastfeeding to 24 months and beyond.

Diurnal Cortisol in Left-Behind Adolescents: Relations to Negative Family Expressiveness and Internalizing Problems.

Despite the accumulating evidence for increased risks for behavioral problems in left-behind adolescents in China, little research has explored their HPA axis functioning, which is hypothesized to play a central role in the association between early adversity and health. In the present study, we designed a longitudinal study to examine HPA axis function in left-behind adolescents and its mediating role in the association between family emotional expressiveness and internalizing problems. Participants were 81 adolescents (44 female; 37 male) aged 11-16 years. Salivary cortisol samples were collected six times a day for two consecutive days on regular school days. Negative family expressiveness (NFE) and internalizing problems were measured using self-report questionnaires. The results showed that NFE was negatively associated with diurnal cortisol, and diurnal cortisol was negatively associated with internalizing problems. Further analysis showed that diurnal cortisol secretion measured by AUC (area under the curve) mediated the association between NFE and internalizing problems. Our findings extended the existing literature about left-behind children via a psychoneuroendocrinological perspective, documenting the negative consequences of the family environment for youth health and development.