Modelling temporal dynamics of suicidal ideation and behaviour across pre- to early adolescence using a Markov framework

2026-08-03

AI Summary

This study investigates the dynamic progression of suicidal ideation, suicidal behavior, and nonsuicidal self-injury (NSSI) among youth aged 9–13, with a specific focus on the transition from ideation to action. Leveraging longitudinal self-report data from the ABCD Study, it introduces a novel approach by integrating time-inhomogeneous discrete-time Markov chains with Bayesian inference to model transitions across eight distinct mental health states and estimate both annual and multiyear transition probabilities. The findings reveal that while overall recovery probabilities are relatively high, the presence of NSSI substantially diminishes the likelihood of recovery, elevates the risk of behavioral persistence, and contributes to trajectory instability and increased predictive uncertainty. This modeling framework offers an interpretable, systematically quantified tool for early warning by characterizing risks of deterioration, remission, persistence, and fluctuation.

Abstract

Understanding the dynamics of suicidal ideation and behaviour in youth and the factors associated with transitions from thoughts to behaviours is critical for early identification, monitoring, and prevention. Using longitudinal self-report data from the Adolescent Brain Cognitive Development (ABCD) Study (n = 11,864) spanning ages 9 to 13 years, we developed a time-inhomogeneous discrete-time Markov chain framework to model transitions across eight states defined by suicidal ideation and behaviour and the co-reported presence or absence of non-suicidal self-injury (NSSI). The framework enables inference of year-to-year and multi-year transition probabilities, quantification of transition stability and uncertainty, and statistical comparison of transition likelihoods. We identified structured but developmentally changing transition patterns, including a generally high probability of recovery to a no-report state following reports of suicidal ideation or behaviour. Co-reported lifetime NSSI marked a distinct trajectory profile characterized by both greater risk and lower predictability: children with NSSI were more likely to transition to or persist in suicidal behaviour, were less likely to recover to a no-report state, and exhibited greater uncertainty in their transition likelihoods compared to those reporting suicidal ideation and/or behaviour alone. These findings suggest that NSSI marks not only elevated risk but also greater trajectory instability during pre- to early adolescence. By estimating probabilities of escalation, remission, persistence, and fluctuation in longitudinal cohort data, the framework provides a systematic, interpretable, and scalable approach to characterising suicidal trajectory dynamics in large, sparse mental health datasets, with potential to inform future research on monitoring, early prevention, and time-varying risk in youth mental health.

Problem

• suicidal ideation
• suicidal behaviour
• non-suicidal self-injury
• temporal dynamics
• adolescence

Innovation

• Markov chain
• suicidal ideation
• non-suicidal self-injury
• longitudinal modeling
• transition dynamics