Childhood Bullying as a Cumulative Health Risk: A Dose-Response Analysis of Peer Victimization and Adult Mental and Behavioral Health Outcomes in Saudi Arabia

Childhood peer victimization is increasingly recognized as an adverse childhood experience (ACE) with long-term consequences for population health. Most existing research treats bullying as a binary exposure, obscuring the dose-response mechanisms through which cumulative victimization generates escalating health risks. This methodological gap is particularly consequential for prevention, and evidence from the Gulf Cooperation Council (GCC) region remains systematically sparse. This study conducts a national dose-response analysis of childhood bullying and adult health outcomes in Saudi Arabia using the WHO Adverse Childhood Experiences International Questionnaire (ACE-IQ), administered to a nationally representative sample of 10,156 adults by the King Abdullah International Medical Research Center (KAIMRC) and the National Family Safety Program (NFSP), Ministry of National Guard Health Affairs (2013). We conducted a cross-sectional secondary analysis examining associations between bullying frequency and five adult health outcomes: physician-diagnosed anxiety disorder, suicidal ideation, sleep disturbance, tobacco smoking, and substance use. The analytical sample comprised 4,632 adults reporting any childhood peer victimization. Binary logistic regression models adjusted for socioeconomic status, gender, age cohort, parental supervision, and family structure were estimated separately for each outcome. Three pre-specified hypotheses were tested: (H1) any bullying exposure is associated with higher odds of adverse adult health outcomes; (H2) increasing frequency follows a dose-response gradient; and (H3) associations are amplified among socioeconomically disadvantaged respondents and attenuated among those reporting higher parental attention. A consistent dose-response gradient was observed. Frequent victims showed substantially higher adjusted odds of tobacco smoking (OR = 6.55, 95% CI 5.81-7.32) and substance use (OR = 2.71, 95% CI 2.26-3.31) compared to those never bullied. Internalizing outcomes showed significant gradients for anxiety disorder (OR = 0.37, 95% CI 0.16-0.86) and sleep disturbance (OR = 0.39, 95% CI 0.20-0.76). Religion-targeted verbal victimization was the strongest independent predictor of suicidal ideation (OR = 3.01, 95% CI 1.83-4.97) and substance use (OR = 3.24, 95% CI 1.92-5.46), independent of bullying frequency. Bullying-health associations were significantly amplified among socioeconomically disadvantaged respondents, consistent with fundamental cause theory. Parental supervision was protective against substance use (OR = 0.45, 95% CI 0.30-0.67) but showed a paradoxical positive association with suicidal ideation, interpreted as a reactive parenting effect in the cross-sectional design. These findings establish childhood bullying as a cumulative, graded public health risk whose consequences are amplified by structural disadvantage. Prevention strategies must extend beyond school-level programs to address structural inequalities and integrate family-based and community-level protective factors. This study contributes population-level ACE evidence from the underrepresented GCC region and provides a foundation for integrating bullying prevention into Saudi Arabia's Vision 2030 national health agenda.