Reciprocal risk: The longitudinal relationship between emotion regulation and non-suicidal self-injury
Poor emotion regulation has been highlighted as a potential risk factor for the development and maintenance of Non-Suicidal Self-Injury (NSSI; Fox et al., 2015). However, longitudinal research tracking the relationship between emotion regulation and NSSI during adolescence is limited. In addition, the conceptual argument that NSSI may in turn be a risk factor for poor emotion regulation (Gratz, 2003), remains largely untested. Three studies, all drawn from the Youth Wellbeing Study, were conducted to investigate the developmental relationship between emotion regulation and NSSI during adolescence. Study One established the psychometric properties of the Emotion Regulation Index for Children and Adolescents in a large sample of adolescents and validated the self-report measure for use in Studies Two and Three. Study Two assessed the longitudinal relationship between emotion regulation and NSSI within a cohort of young adolescents across a three year period. Consistent with previous research, poor emotion regulation predicted subsequent engagement in NSSI for both boys and girls, suggesting that poor emotion regulation may be causally implicated in the development of NSSI behaviours. Critically, this relationship was reciprocal; engaging in NSSI also predicted poorer subsequent emotion regulation. Study Three tests the hypothesis that NSSI ‘damages’ emotion regulation by impairing the interpersonal relationships which underlie the development of emotion regulation skills. Using a quasi-longitudinal multiple mediation analysis, the combination of Time Two Parental Attachment and Time Two Peer Attachment were found to fully mediate the relationship between Time One NSSI and Time Three Emotion Regulation, emphasising the primacy of these relationships during adolescence. This research is the first to empirically demonstrate the reciprocal complexity of the relationship between emotion regulation and NSSI, suggesting that the dynamic relationship between these two factors underlies the development of NSSI during adolescence.