Alone in the aftermath: A nationwide prospective study on the role of loneliness in depression-driven suicidal ideation following the October 7, 2023, terrorist attack

Introduction: The October 7, 2023, terrorist attack in Israel resulted in widespread psychological distress, significantly impacting mental health at a national level. This study examines the longitudinal relationship between depression and suicidal ideation (SI) in the aftermath of mass trauma, with a particular focus on the moderating role of loneliness. Given prior research demonstrating the link between depression and SI, this study seeks to explore whether loneliness exacerbates this association over time, thereby informing targeted suicide prevention efforts. Methods: This study employed a nationally representative prospective design with a cohort of 600 Israeli civilians (Mage = 41.02, SD = 13.79; 50.3% women). Data were collected at five time points: two months pre-attack (T1), one-month post-attack (T2), and three additional follow-ups across one year (T3–T5). Participants completed validated self-report measures assessing depression, SI, and loneliness, with pre-attack depression levels serving as a covariate. Hierarchical regression and moderation analyses were conducted to assess the interaction between depression and loneliness in predicting SI at T5. Results: Probable depression at T2 significantly predicted SI at all subsequent time points. Furthermore, loneliness at T2 independently contributed to SI at T5, beyond the effects of pre-existing depression and trauma-related factors. Crucially, moderation analyses revealed that loneliness T2 amplified the association between depression T2 and SI T5, such that individuals with high loneliness exhibited a stronger depression-SI link over time. Discussion: Findings highlight the compounding effect of depression and loneliness on suicide ideation in the aftermath of mass trauma. The results suggest that loneliness may act as a critical mechanism that sustains suicidality by reinforcing isolation and limiting access to emotional support. This study underscores the need for trauma-informed suicide prevention strategies that incorporate interventions aimed at reducing loneliness, enhancing interpersonal connectedness, and promoting social reintegration.