There is increasing knowledge that the COVID-19 pandemic has had an impact on mental health of children and young people. However, the global evidence of mental health changes before compared to during the COVID-19 pandemic focusing on children and young people has not been systematically reviewed. This systematic review examined longitudinal and repeated cross-sectional studies comparing before and during COVID-19 pandemic data to determine whether the mental health of children and young people had changed before and during the COVID-19 pandemic. The Web of Science, PubMed, Embase and PsycINFO databases were searched to identify peer-reviewed studies that had been published in English and focused on children and young people between 0 and 24 years of age. This identified 21 studies from 11 countries, covering more than 96,000 subjects from 3 to 24 years of age. Pre-pandemic and pandemic data were compared. Most studies reported longitudinal deterioration in the mental health of adolescents and young people, with increased depression, anxiety and psychological distress after the pandemic started. Other findings included deteriorated negative affect, mental well-being and increased loneliness. Comparing data for pandemic and pre-pandemic periods showed that the COVID-19 pandemic may negatively impact the mental health of children and young people. There is an urgent need for high-quality research to address the impact, risks and protective factors of the pandemic on their mental health, as this will provide a good foundation for dealing with future health emergencies and other crises.

This study reports time-trend changes in self-reported mental health problems, smoking, and alcohol habits among Finnish adolescents over a 16-year period using three cross-sectional studies with similar designs, methodologies, and geographical recruitment areas. There were 4508 participants with a mean age of 14.4 years (range 13-18) in 1998 (n = 1449), 2008 (n = 1560), and 2014 (n = 1499). The information they provided on their mental health was measured with the Strengths and Difficulties Questionnaire and they were also asked questions about their alcohol and smoking habits. The findings showed that from 1998 to 2014 females reported less hyperactivity and conduct problems and males reported fewer peer problems and better prosocial skills. The only mental health problem that showed a significant increase was emotional symptoms among females. Smoking and alcohol use consistently decreased in males and females during the 16-year period. Our findings suggest that overall adolescent's self-reported mental health problems were either stable or falling, indicating increased well-being. The decreased smoking indicates that anti-smoking campaigns have been successfully changing teenagers' attitudes towards smoking. The important finding is that self-reported emotional symptoms had increased in females. This may indicate an increase or earlier onset of affective disorders.

Loneliness was a common phenomenon in childhood, and no notable changes were found during the 24-year study period. Psychiatric symptoms were strongly associated with loneliness. It is important to pay attention to children's loneliness and make it an integral part of school health care. Further epidemiological research is needed.

There has been a lack of studies on bullying in non-western low-income and middle-income countries. This study reported the prevalence of traditional victimization, cybervictimization, and the combination of these, in 13 European and Asian countries, and explored how psychiatric symptoms were associated with victimization. The data for this cross-sectional, school-based study of 21,688 adolescents aged 13–15 were collected from 2011 to 2017. The main outcomes were traditional and cybervictimization obtained from student self-reports. The Strengths and Difficulties Questionnaire was used to assess psychiatric symptoms. Generalized estimating equation and logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs). The mean prevalence of any victimization was 28.9%, of traditional victimization only, this was 17.7%, and for cybervictimization only this was 5.1%. Cybervictimization occurred both independently, and in combination with, traditional victimization. The mean prevalence of combined victimization was 6.1%. The mean proportion of those who were cyberbullied only among those who were either cyberbullied only or bullied both traditionally and in cyber was 45.1%. The rates of prevalence varied widely between countries. In the total sample, those who experienced combined victimization, reported the highest internalizing symptoms (girls, OR 1.25, 95% CI 1.22–1.29; boys, OR 1.29, 95% CI 1.25–1.33). The study findings suggest that anti-bullying interventions should include mental health components and target both traditional and cyberbullying. Due to the overlap between these, targeting bullying should primarily focus on how to reduce bullying behavior rather than just focusing on where bullying takes place.

Maezono, J., Hamada, S., Sillanm€ aki, L., Kaneko, H., Ogura, M., Lempinen, L. & Sourander, A. (2019). Cross-cultural, population-based study on adolescent body image and eating distress in Japan and Finland. Scandinavian Journal of Psychology, 60, 67-76.This cross-sectional population-based survey compares the prevalence of self-reported body image and eating distress symptoms among adolescents in Japan and Finland, and associations between emotional/behavioral problems, body image and eating distress from a cross-cultural perspective. The study included 1,840 Japanese and 1,135 Finnish 8th grade students. The self-reported questionnaire included the Body Image and Eating Distress Scale and Strengths and Difficulties Questionnaire (SDQ). The female adolescents from both Finland and Japan reported much greater dissatisfaction with, and concern about, their bodies than the males and Japanese females expressed even higher distress than Finnish females. High levels of body image and eating distress were associated with psychiatric problems measured with the SDQ. There was a significant three-way interaction effect of body image and eating distress, gender and country with SDQ peer problems and prosocial behavior.