The role of youths' cardiac autonomic balance and parental responses to youth emotion in vulnerability to borderline personality disorder development.

Developmental models of borderline personality disorder (BPD) emphasize the effects of youths' biological vulnerabilities and their experiences of parental responses to emotion, as well as the interaction between these two elements. The current study evaluated the independent and interactive effects of two indices of autonomic nervous system response and parental responses to youth negative emotions on severity and exacerbation of youths' BPD features during the transition to adolescence. The sample consisted of 162 psychiatric youth (10-14 years; 47.2% female) and their parents. At baseline, youth and their parents completed a lab-based conflict discussion during which parasympathetic and sympathetic nervous system response were measured and indices of sympathetic-parasympathetic balance and coactivation/coinhibition were calculated. Youth also reported on supportive and non-supportive parental responses. At baseline and after 9 months, youth self-reported on their BPD features. Results demonstrated that shifting toward sympathetic dominance independently predicted exacerbation of BPD across 9 months. Additionally, fewer experiences of supportive parental responses and more non-supportive parental responses were associated with greater severity of BPD features in youth. This study highlights the role of autonomic response to parent-child conflict as well as the significance of parental responses to youth emotion for the development of BPD during this developmental window.