Bullying at school has far-reaching impacts on adolescent well-being and health. The aim of this study was to examine trends in bullying at school according to socioeconomic adversities among Finnish adolescents from 2000 to 2015. A population-based school survey was conducted biennially among 14-16-year-old Finns between 2000 and 2015 (n = 761,278). Distributions for bullying, being bullied and socioeconomic adversities were calculated. Associations between bullying involvement, time and socioeconomic adversities were studied using binomial logistic regression with results shown by odds ratios with 95% confidence intervals. At the population level, the likelihoods of bullying and being bullied varied only slightly between 2000 and 2015. Bullying and being bullied were associated with socioeconomic adversities (low parental education, not living with both parents and parental unemployment in the past year). Unlike in the general population, the likelihoods of bullying and being bullied increased markedly among adolescents with most socioeconomic adversities. The increased socioeconomic differences in bullying involvement observed in this study add to the mounting evidence of polarization of adolescent health and well-being. Socioeconomic adversities should be considered in the prevention of bullying at school. In addition, socio-political measures are needed to decrease socioeconomic inequalities among Finnish adolescents.

Smoking is a significant cause of morbidity and mortality worldwide. In the past decades, the prevalence of adolescent smoking has decreased in industrial countries. However, whether the decreasing trend can be seen across all socioeconomic groups is unknown. The aim of this study was to examine time trends in adolescent smoking according to the socioeconomic status among Finnish adolescents between 2000 and 2015. Methods: A population-based school survey was conducted biennially among 14-to 16-year-old Finns between 2000 and 2015 (n ¼ 761,278). Distributions for frequent smoking, lifelong nonsmoking, and socioeconomic adversities (low parental education, not living with both parents and parental unemployment during the past year) were calculated. Associations were studied using binomial logistic regression results shown by odds ratios with 95% confidence intervals. Results: Frequent smoking was positively associated and lifelong nonsmoking was negatively associated with socioeconomic adversities. Over the study period, the overall prevalence of frequent smoking decreased and lifelong nonsmoking increased. However, no similar changes were observed among adolescents with most socioeconomic adversities. Conclusion: Socioeconomic differences in adolescent smoking increased in Finland between 2000 and 2015. Although the overall prevalence of frequent smoking decreased, no similar decrease was observed among adolescents with most socioeconomic adversities. Similarly, although the overall prevalence of lifelong nonsmoking increased, this was not observed among adolescents with most socioeconomic adversities. Socioeconomic adversities should be considered in the prevention of adolescent smoking.

Background: Scientific literature suggests that the prevalence of delinquency amongst adolescents has decreased internationally in past decades. However, whether this change is consistent across all socioeconomic groups has not yet been studied. Objective: The aim of this study was to examine changes in delinquency amongst Finnish adolescents according to socioeconomic status between 2000 and 2015. Method: A population-based school survey was conducted biennially amongst 14-16-year-old Finns between 2000 and 2015 (n = 761,278). Distributions for delinquency and socioeconomic adversities (low parental education, not living with both parents and parental unemployment in the past year) were calculated using crosstabs. Associations between delinquency, time, and socioeconomic adversities were studied using binomial logistic regression results shown by odds ratios with 95 % confidence intervals. Results: Delinquency was positively associated with all three socioeconomic adversities studied and cumulative socioeconomic adversity. Although the prevalence of delinquency varied only slightly between 2000 and 2015 in the overall population, it increased significantly amongst adolescents with most socioeconomic adversities. Conclusions: The findings indicate that socioeconomic differences in delinquency have increased amongst Finnish adolescents in past decades. Delinquency prevention and intervention programs should take socioeconomic adversities into account.

Background: Mental health problems are common in adolescence and seeking help for them is becoming more common. Referrals to adolescent mental healthcare have recently increased in Finland. Objective: To examine time trends in internalizing and externalizing mental health symptoms among Finnish adolescents. Method: A time-trend school survey was conducted among 9 th graders (15-year-olds) in Tampere, Finland, in three time periods : 2002-03, 2012-13 and 2018-19 (N = 4,162). Results: Compared to the period 2002-03, prevalence of externalizing symptoms decreased in the period 2012-13 and further in 2018-19. The prevalence of internalizing symptoms did not change significantly between 2002-03 and 2012-13; however, in 2018-19, depression, social anxiety, general anxiety, poor subjective health, stress symptoms among boys, and poor selfesteem increased compared to earlier time periods. The increases were more marked among girls. However, suicidal ideation did not increase in 2018-19 compared to earlier time periods. Conclusion:Whereas the prevalence of externalizing symptoms decreased among Finnish adolescents between 2002-03 and 2018-19, the prevalence of internalizing symptoms increased between 2012-13 and 2018-19. To help to understand the causes of these increases and to prevent internalizing problems, further research on the underlying causes is needed.

Background Despite reduced sanctions and more permissive attitudes toward cannabis use in the USA and Europe, the prevalences of adolescent cannabis use have remained rather stable in the twenty-first century. However, whether trends in adolescent cannabis use differ between socioeconomic groups is not known. The aim of this study was to examine trends in cannabis use according to socioeconomic status among Finnish adolescents from 2000 to 2015. Methods A population-based school survey was conducted biennially among 14–16-year-old Finns between 2000 and 2015 (n = 761,278). Distributions for any and frequent cannabis use over time according to socioeconomic adversities were calculated using crosstabs and chi-square test. Associations between any and frequent cannabis use, time, and socioeconomic adversities were studied using binomial logistic regression results shown by odds ratios with 95% confidence intervals. Results At the overall level, the prevalences of lifetime and frequent cannabis use varied only slightly between 2000 and 2015. Cannabis use was associated with socioeconomic adversities (parental unemployment in the past year, low parental education, and not living with both parents). The differences in any and frequent cannabis use between socioeconomic groups increased significantly over the study period. Conclusions Although the overall changes in the prevalence of adolescent cannabis use were modest, cannabis use increased markedly among adolescents with the most socioeconomic adversities. Socioeconomic adversities should be considered in the prevention of adolescent cannabis use.