Understanding the role of dissociation and emotional dysregulation on suicidal ideation: a comprehensive analysis and a proposed self-report assessment measure

Suicide and suicidal ideation (SI) are major public health concerns with severe individual and societal impacts. The World Health Organization (2025) emphasizes the urgent need to develop effective preventive interventions grounded in a comprehensive and integrated understanding of the psychological mechanisms underlying SI, supported by reliable and valid assessment tools. This research project was conceived and developed in response to this need, adopting a multidimensional approach that explores facets of SI. Chapter 1. examines the relationship between different domains of dissociation and suicidal outcomes. A systematic review including 84 studies, of which 68 were included in the meta-analysis, was conducted using a random-effects model and moderation analyses to account for study heterogeneity, while controlling for publication bias and evaluating methodological quality. The results indicate that general dissociation is significantly correlated with suicide risk, suicidal ideation, and suicide attempts. Significant positive associations were found between suicidal ideation and detachment, as well as maladaptive daydreaming. Although the association between suicide attempts and somatoform dissociation was small but significant, this dimension showed a stronger connection with suicidal ideation. Chapter 2. consists of two cross-sectional empirical studies. The first study compares a clinical sample of psychiatric patients with a history of suicidality (N = 91; Mage = 40.4, SD = 17.3) with a control group (N = 81; Mage = 26.6, SD = 10.8), investigating the role of emotional dysregulation and dissociation as transdiagnostic vulnerabilities. Generalized linear models (GLMs) revealed significantly higher levels of emotional dysregulation and dissociation in the clinical group, with moderate correlations between these dimensions and SI within the same group. The second study employed a Structural Equation Models (SEMs) on 448 participants recruited from the community (Mage = 26.4; SD = 8.43) to analyse the interaction between emotional dysregulation, dissociation, and maladaptive personality traits in predicting different facets of SI. Results showed that emotional dysregulation predicted active SI, whereas somatoform dissociation was associated with both passive and active SI. Furthermore, traits such as negative affectivity, disinhibition, and psychoticism indirectly influenced SI through these psychological processes, highlighting the relevance of an integrated approach. Finally, Chapter 3. addresses the need for valid and theoretically grounded psychometric instruments to assess the multifaceted nature of SI. Through the development and preliminary validation of the MEntal states related to Suicidal Ideation Scale (MESIS), a factorial structure was confirmed that differentiates among several types of SI and associated mental states, identifying intra - and interpersonal emotional regulation functions underlying the development of SI. Overall, this project advances a comprehensive understanding of SI and promotes the development of accurate self-report measures for early detection and further targeted intervention, identifying emotional dysregulation and dissociation as key psychological processes to be emphasized in suicide risk prevention strategies.