Continuity and Stability of Child and Adolescent Depressive Symptoms in South Korea: A Meta-analysis of Longitudinal Studies

Many adolescents in South Korea experience risk-level depressive symptoms due to stress caused by personal and environmental changes. Prior studies investigated various characteristics of depressive symptoms. However, it is unclear when the mean level of depression changes with the development of children and adolescents and whether it is stable relative to one another over time. Thus, it is necessary to closely understand the continuity and stability of depressive symptoms across developmental stages in children and adolescents. In this study, continuity refers to the consistency in a group's mean level of depressive symptoms over time; however, stability refers to the consistency in the relative placement of the levels of depressive symptoms of individuals within a group over time. To comprehensively understand previous studies, this meta-analysis compiled data from 95 South Korean longitudinal studies (N = 200,338; 49.7% females) published between 2000 and 2021. Data were analyzed using a three-level random effects model with a 1-year interval for each age group to integrate effect sizes, followed by a generalized additive mixed model integrating age as a continuous variable. The results indicate that the mean-level continuity of depressive symptoms was relatively high and the rank-order stability was low for the children in elementary school (including both upper and lower grades). Additionally, as the adolescents aged, the mean-level continuity of depressive symptoms slightly decreased while stability increased. When entering early adulthood, the continuity and stability of depressive symptoms converged without significant change. As a result of moderating effect, the female-only group indicated a high level of continuity and stability than the male-only or mixed group. The findings highlight that South Korean childhood is a period of relatively high continuity and low stability. Moreover, female students' depressive symptoms fluctuate more than those of males, suggesting the need for providing effective and appropriate help.