Developmental pathways of suicidality and self-harm among youth

Abstract

Suicidality and self-harm among youth are significant public health concerns. This thesis seeks to elucidate the developmental pathways and predictors underpinning these issues, with a particular emphasis on the roles of bullying victimisation (or peer victimisation), parental mental health, youth problem behaviours, and screen time use. Chapter 2 utilised the Zurich Project on the Social Development from Childhood to Adulthood (z-proso) and employed random-intercept cross-lagged panel models to investigate whether bullying victimisation has associations with suicidal ideation and self-harm. The analysis suggested a positive within-person effect between general bullying victimisation at age 15 and suicidal ideation at age 17. Intriguingly, this association is bidirectional, with suicidal ideation at age 17 subsequently leading to general bullying victimisation at age 20. Building on these findings, Chapter 3 examined the mediating roles of depressive symptoms, anxiety symptoms, and substance use in the associations between bullying victimisation and suicidal ideation, focusing on within-person effects. Contrary to expectations, bullying victimisation did not predict subsequent within-person increases in suicidal ideation through these mediators. In Chapter 4, data from the UK’s Millennium Cohort Study (MCS) and a parallel-process latent class growth analysis (LCGA) were utilised to examine the co-developmental trajectories of parental mental health issues and child internalising and externalising problems from early childhood to middle adolescence, as well as their associations with self-harm and suicidal attempts in adolescence. The findings highlight the significance of taking parental distress (especially maternal) and child problem behaviours into account when addressing negative outcomes such as self-harm and suicidal attempts. Chapter 5 examined the role of developmental patterns of screen time during adolescence in suicidality, self-harm, and other mental health and behavioural issues in young adults. Analysis of the z-proso study and a parallel-process LCGA indicated that youths in the trajectory group of increasing videogame and internet use displayed a higher risk for suicidal ideation and self-harm at age 20. This highlights the critical role of screen usage patterns as potential markers of later suicidality and self-harm risk; however, additional examinations are needed to test this association. Overall, this work illuminates the multifaceted developmental predictors of suicidality and self-harm in youth.