自殺的アイデンティティ発達の階層的精神力動モデル：自己と自己感覚の同一化

Suicide in adolescents and emerging adults is often understood through symptoms and risk factors rather than as a disturbance of the self. This article presents a conceptual analysis and model building study that elaborates the Existential Network of Suicidal Identity (ENSI) with a specific focus on existential anchors and the senses of self they support. Drawing on object relations and defense theory, mentalization and attachment research, existential psychology on meaning and psychache, and narrative identity work on coherence and foreclosure, we develop a layered psychodynamic account of suicidal identity that is sensitized to equity contexts such as racism, gendered violence, poverty, LGBTQ+ stigma, disability, rurality, and barriers to care. ENSI is reconceptualized around five existential anchors - purpose, value, self-worth, relational safety, and felt safety - which scaffold corresponding senses of self related to meaning and direction, being valued and belonging, narrative agency, emotional containment with others, and basic bodily security. When anchors are eroded across development, these senses of self weaken, internal objects become less stable, defenses such as splitting, projection, and projective identification intensify, and suicidal identity consolidates. We outline how the model clarifies three cross cutting mechanisms of collapse (Fractured Self Continuum, Suicidal Pursuit of Goals, Controls of Self Deception) and translate these into nursing heuristics for assessment, collaborative formulation, and intervention that complement structured safety planning. ENSI offers a theoretically grounded, testable framework for identity informed and equity aware suicide prevention in psychiatric nursing.