This study investigated the complex relationships between adverse childhood experiences (ACE), post-traumatic stress symptoms (PTSS), and substance use disorder (SUD) following a large-scale collective trauma in Israel. We utilized a longitudinal design with a quasi-representative sample of 1,343 Jewish Israeli adults, measuring PTSS and SUD both before (April 2022) and after (December 2023) the October 7th attack. Using regression analysis and structural equation modeling, we tested the sensitization and self-medication hypotheses, and the direct effect of ACE on SUD beyond PTSS. Results demonstrate that higher ACE scores significantly predicted greater elevations in PTSS following the trauma, supporting the sensitization hypothesis. Pre-trauma PTSS significantly predicted increases in SUD, consistent with the self-medication hypothesis. Critically, ACE directly predicted an elevation in SUD even when controlling for PTSS. SEM analysis provided evidence for a direct contribution of ACE to changes in SUD after the collective trauma. This provides new evidence suggesting that early adversity confers a distinct, independent risk for SUD that is not solely mediated by post-traumatic stress. These findings underscore the profound and multifaceted impact of childhood experiences on long-term well-being and highlight the need for trauma-informed interventions that address both immediate stress reactions and the enduring consequences of early adversity.

Keywords: Adverse childhood experiences; Post-traumatic stress symptoms; Substance use disorder; Collective trauma; Israel-Hamas war