Parent-child relationship quality buffers the association between mothers' adverse childhood experiences and physiological synchrony.

Background: Family environment plays a critical role in shaping stress response systems. Concordance between mothers' and children's physiological states, specifically their Respiratory Sinus Arrhythmia (RSA), reflects dyadic co-regulation. Negative or weakened RSA synchrony during interactions is linked to various psychosocial risks, but existing research has focused on risks in the mother or child as opposed to the dyad. This study examined the association between maternal-child RSA synchrony and maternal ACEs, given documented associations with offspring RSA, as well as more proximal documented risks, including maternal psychopathology and children's early adversity and psychopathology. Given that sensitive parent-child relationships are a powerful source of resilience, we tested whether parent-child relationship quality buffered associations between maternal ACEs and RSA synchrony.

Methods: In a community sample of mother-child dyads experiencing high sociodemographic risk and oversampled for exposure to adversity, mothers (n = 123) reported on their ACEs (43.1% ≥4), their 3-5-year-old children's exposure to violence, and psychological symptoms. Dyads completed a puzzle task while EKG was recorded, from which maternal and child RSA was derived; parent-child relationship quality during interactions was coded observationally. Multilevel models examined within-dyad mother-child RSA synchrony across the interaction and between-dyad predictors of synchrony.

Results: Parent-child relationship quality and maternal ACEs co-contributed to offspring and dyadic physiology. Maternal ACEs predicted dampened RSA in the child and dampened RSA synchrony in the dyad, only among dyads with low observer-rated parent-child relationship quality during the interaction. In other words, high-quality parent-child relationship quality buffered the association between maternal ACEs and dampened offspring and dyadic physiology.

Conclusions: Results suggest that mothers' early adversity may disrupt physiological regulation at both the individual child and dyadic level. High-quality parent-child relationships mitigated this effect.