Investigation of the Trend in Adolescent Mental Health and its Related Social Factors: A Multi-Year Cross-Sectional Study For 13 Years.

We aimed to investigate the mental health change and associated social correlates in adolescents in terms of depression, suicidal ideation, and suicidal attempt. In total, 978,079 students (12-18 years old, 7th-12th grade) participated in the survey for 13 years (2006-2018) by a multiple-year cross-sectional design (not a repeat measure for smaller group). Mental health outcome variables were assessed using self-report surveys with the independent variables of sex, age, economic status, school achievement, and parental educational level. Korean social indices of income inequality (Gini index, higher scores representing greater economic inequity with score range of 0-1), education (national proportion of tertiary education attainment), and actual suicides were investigated together as related social factors. The prevalence of depressive episodes, suicidal ideation, and suicidal attempt markedly dropped by 34.6%, 42.2%, and 48.3%, respectively. Moreover, the Gini index (from 0.314 in 2008 to 0.295 in 2015) and proportion of tertiary education (from 82.1% in 2006 to 69.7% in 2018) showed a decreasing tendency. These indices and adolescent mental health outcomes highly correlated with each other (Pearson's r between Gini index and depressive episode = 0.789, suicidal ideation = 0.724, and suicidal attempt = 0.740; Pearson's r between proportion of tertiary education and depressive episode = 0.930, suicidal ideation = 0.809, and suicidal attempt = 0.851). Adolescent mental health has improved in the last 13 years in Korea, and improvements in social inequality (decreased Gini index) and lessened burden of academic competition (decreased national proportion of tertiary education) were significantly associated with the improvement of adolescent's mental health. However, the impact of parental educational level on children's mental health was relatively minimal, compared with the impact of economic inequality and academic burden. Further studies are needed to reveal the underlying mechanism for the association between adolescent mental health and sociodemographic factors to save adolescents from psychological distress.