Association between biological rhythm disruption and suicidal ideation in patients with major depressive disorder: a chain mediation of neuroticism and emotion regulation difficulties.

BACKGROUND: Biological rhythm disruption is commonly observed in patients with major depressive disorder (MDD), but the psychological mechanisms linking it to suicidal ideation remain unclear. This study examined whether neuroticism and emotion regulation difficulties mediate this relationship. METHODS: This study included 275 eligible patients with MDD. Biological rhythm disruption, neuroticism, emotion regulation difficulties, and suicidal ideation were assessed using the Biological Rhythms Interview of Assessment in Neuropsychiatry (BRIAN), the NEO Five-Factor Inventory-Neuroticism subscale (NEO-FFI-N), the 16-item Difficulties in Emotion Regulation Scale (DERS-16), and the Self-rating Idea of Suicide Scale (SIOSS), respectively. A chain mediation analysis was conducted using the PROCESS macro (Model 6). RESULTS: Of the 275 participants, 73.8% reported suicidal ideation. Path analysis showed that biological rhythm disruption had a significant direct association with suicidal ideation (effect = 0.055, 95% CI: 0.007-0.102) and indirect associations through three pathways: (1) via neuroticism alone (effect = 0.086, 95% CI: 0.055-0.121); (2) via emotion regulation difficulties alone (effect = 0.036, 95% CI: 0.017-0.058); and (3) via their serial mediation (effect = 0.021, 95% CI: 0.010-0.034). The total indirect effect accounted for 72.31% of the total effect. CONCLUSIONS: Biological rhythm disruption is not only directly associated with suicidal ideation but also indirectly associated with it through the independent and serial mediating pathways of neuroticism and emotion regulation difficulties in patients with MDD. These findings underscore the potential of interventions that target biological rhythm stabilization, reduce neuroticism-related vulnerability, and enhance emotion regulation to mitigate suicide risk.