Daily nonsuicidal self-injury thoughts in emerging adulthood: The relevance of pre-adolescent borderline traits.

Longitudinal studies exploring the role of early personality vulnerabilities as risk factors for later NSSI dynamics are scarce. In this study, we assess how pre-adolescent borderline personality pathology (BPP) traits (assessed at mean age 12.78; SD age = 1.38, age range = 7.17-14.78) shape dynamic links between daily socio-emotional dysregulation and NSSI thoughts during emerging adulthood ( M age = 20.96, SD age = 1.63). Mothers of 131 children completed questionnaires about their child's BPP traits in pre-adolescence. These children were re-assessed eight years later and were asked to complete a daily diary for 14 consecutive days. During these 14 days, behavioral and emotional dysregulation as well as NSSI thoughts were self-reported. Multilevel structural equation modeling was used (1) to examine dynamic links between socio-emotional dysregulation manifestations and NSSI thoughts in early adulthood, and (2) to explore the role of pre-adolescent BPP traits in moderating these early-adult dynamic associations. Our findings suggest that young adults who were described by their mothers as high on BPP traits (especially anxious and paranoid traits) during pre-adolescence, tended to respond more with NSSI thoughts when experiencing dysregulation or when perceiving others as rejecting in young adulthood. Results are discussed in terms of potential targets for indicated prevention of NSSI development.