Social media use (SMU) has become an intrinsic part of adolescent life. Negative consequences of SMU for adolescent health could include exposures to online forms of aggression. We explored age, gender, and cross-national differences in adolescents' engagement in SMU, then relationships between SMU and victimization and the perpetration of cyber-bullying. We used data on young people aged 11-15 years (weighted n = 180,919 in 42 countries) who participated in the 2017-2018 Health Behaviour in School-aged Childrenstudy to describe engagement in the three types of SMU (intense, problematic, and talking with strangers online) by age and gender and then in the perpetration and victimization of cyber-bullying. Relationships between SMU and cyber-bullying outcomes were estimated using Poisson regression (weighted n = 166,647 from 42 countries). Variations in SMU and cyber-bullying follow developmental and gender-based patterns across countries. In pooled analyses, engagement in SMU related to cyber-bullying victimization (adjusted relative risks = 1.14 [95% confidence interval (CI): 1.10-1.19] to 1.48 [95% CI: 1.42-1.55]) and perpetration (adjusted relative risk = 1.31 [95% CI: 1.26-1.36] to 1.84 [95% CI: 1.74-1.95]). These associations were stronger for cyber-perpetration versus cyber-victimization and for girls versus boys. Problematic SMU was most strongly and consistently associated with cyber-bullying, both for victimization and perpetration. Stratified analyses showed that SMU related to cyber-victimization in 19%-45% of countries and to cyber-perpetration in 38%-86% of countries. Accessibility to social media and its pervasive use has led to new opportunities for online aggression. The time adolescents spend on social media, engage in problematic use, and talk to strangers online each relate to cyber-bullying and merit public health intervention. Problematic use of social media poses the strongest and most consistent risk.

Previous research has shown inconsistent time trends in adolescent mental well-being, but potential underlying mechanisms for such trends are yet to be examined. This study investigates cross-national time trends in adolescent mental well-being (psychosomatic health complaints and life satisfaction) in mainly European countries and the extent to which time trends in schoolwork pressure explain these trends. Data from 915,054 adolescents from 36 countries (50.8% girls; meanage = 13.54; standard deviationage = 1.63) across five Health Behaviour in School-aged Children surveys (2002, 2006, 2010, 2014, and 2018) were included in the analyses. Hierarchical multilevel models estimated cross-national trends in adolescent mental well-being and schoolwork pressure. We also tested whether schoolwork pressure could explain these trends in mental well-being. A small linear increase over time in psychosomatic complaints and schoolwork pressure was found. No change in life satisfaction emerged. Furthermore, there was large cross-country variation in the prevalence of, and trends over time in, adolescent mental well-being and schoolwork pressure. Overall, declines in well-being and increases in schoolwork pressure were apparent in the higher income countries. Across countries, the small increase in schoolwork pressure over time partly explained the decline in psychosomatic health complaints. Our findings do not provide evidence for substantial declines in mental well-being among adolescents. Yet, the small declines in mental well-being and increases in schoolwork pressure appear to be quite consistent across high-income countries. This calls for the attention of public health professionals and policy-makers. Country differences in trends in both adolescent mental well-being outcomes and schoolwork pressure were considerable, which requires caution regarding the cross-national generalization of national trends.

Background: Bullying among children and adolescents is a public health concern; victimization is associated with psychological and physical health problems. The purpose of this study is to examine temporal trends in bullying victimization among school-aged children in Europe and North America. Methods: Data were obtained from cross-sectional self-report surveys collected as part of the Health Behaviour in School-aged Children (HBSC) study from nationally representative samples of 11-, 13- and 15-year-olds, from 33 countries and regions which participated in the 2001–02, 2005–06 and 2009–10 surveys. Responses from 581 838 children were included in the analyses. Binary logistic regression was used for the data analyses. Results: The binary logistic regression models showed significant decreasing trends in occasional and chronic victimization between 2001–02 and 2009–10 across both genders in a third of participating countries. One country reported significant increasing trends for both occasional and chronic victimization. Gender differences in trends were evident across many countries. Conclusion: Overall, while still common in many countries, bullying victimization is decreasing. The differences between countries highlight the need to further investigate measures undertaken in countries demonstrating a downward trend.

Social patterns in bullying show consistent gender differences in adolescent perpetration and victimization with large cross-national variations. Previous research shows associations between societal gender inequality and gender differences in some violent behaviors in adolescents. Therefore, there is a need to go beyond individual associations and use a more social ecological perspective when examining gender differences in bullying behaviors. The aim of the present study was twofold: (1) to explore cross-national gender differences in bullying behaviors and (2) to examine whether national-level gender inequality relates to gender differences in adolescent bullying behaviors. Traditional bullying and cyberbullying were measured in 11-year-olds to 15-year-olds in the 2017/18 Health Behaviour in School-aged Children study (n = 200,423). We linked individual data to national gender inequality (Gender Inequality Index, 2018) in 46 countries and tested their association using mixed-effects (multilevel) logistic regression models. Large cross-national variations were observed in gender differences in bullying. Boys had higher odds of perpetrating both traditional and cyberbullying and victimization by traditional bullying than girls. Greater gender inequality at country level was associated with heightened gender differences in traditional bullying. In contrast, lower gender inequality was associated with larger gender differences for cyber victimization. Societal gender inequality relates to adolescents' involvement in bullying and gendered patterns in bullying. Public health policy should target societal factors that have an impact on young people's behavior.