Developmental trajectories of suicidality and lifestyle factors across adolescent severity profiles

Background: Adolescent suicide is a leading cause of death in Australia, arising from multiple determinants. Psychological distress, lifestyle behaviours and socioeconomic factors are associated with adolescent suicidality. Existing research has predominantly employed cross-sectional designs, limiting our understanding of how these factors interact over time. Longitudinal and data-driven approaches are needed to help identify the factors associated with the emergence of suicidality throughout adolescence. Method: Participants aged 12-17 years completed longitudinal measures of suicidal ideation, psychological distress, sleep quality, mindfulness, physical activity, eating habits, and social connectedness. Subgroups were determined via hierarchical cluster analysis, based on average scores across later timepoints (9-15). ANOVA and pairwise effect size calculations were used to compare clusters across variables, and their preceding developmental trajectories were examined using generalised additive mixed models (across earlier timepoints; 1-8). Clusters were also compared on self-reported wellbeing, long-term suicidality, and socioeconomic status. Result: Three clusters characterised by low-, moderate-, and high-severity of suicidal ideation and psychological distress, and poorer sleep, social connectedness, physical activity, mindfulness, and eating habits were identified. Across earlier timepoints, the high-severity group showed consistently elevated suicidality and deteriorating wellbeing and lifestyle scores. Conclusion: Youth with high levels of suicidality had greater psychological distress, lower wellbeing, lower socioeconomic status, and poorer lifestyle behaviours. This subgroup was also found to have poorer scores on wellbeing and lifestyle factors in their early adolescence. Findings highlight the importance of early, preventative interventions targeting both mental health and lifestyle factors to reduce suicidality in adolescents.