Mediators of the association between psychotic experiences and future non-suicidal self-injury and suicide attempts: results from a three-wave, prospective adolescent cohort study

Psychotic experiences (PEs) are robustly associated with subsequent non-suicidal self-injury (NSSI) and suicide attempts, but questions remain as to the temporal relation and underlying cause of this association. Most investigations have incorporated only two waves of data, and no study has comprehensively investigated mediating pathways. This study aimed to investigate both the PE-NSSI and PE-suicide attempt association, and their relevant mediators, across three waves of prospective data. Participants were from an Australian prospective longitudinal cohort of 1100 adolescents (12-17 years); data were collected at three time points over 2 years. NSSI and suicide attempts were measured using the Self-Harm Behaviour Questionnaire. Items from the Diagnostic Interview Schedule for Children were used to assess four PE subtypes (auditory hallucinatory experiences [HEs] and three delusional experiences). Potential mediators of interest included: psychological distress, self-reported mental disorders, self-esteem, recent traumatic life events (e.g. bullying, sexual assault), emotion regulation, and impulsivity/other personality traits. Analyses were adjusted for sociodemographics and substance use. Auditory HEs were indirectly associated with future NSSI and suicide attempts via recent traumatic life events, high psychological distress, and low self-esteem, across three waves of data. Other PE subtypes were generally not associated with incident NSSI/suicide attempts at 1- and 2-year follow-up, either directly or indirectly. These findings highlight the importance of screening for auditory HEs when assessing a young person's self-harm/suicide risk. Clinical assessment would be further enhanced by a comprehensive review of recent interpersonal traumatic events, as well as levels of self-esteem and distress.