Risk and protective factors for depression that adolescents can modify: A systematic review and meta-analysis of longitudinal studies

Background: Adolescence is a peak time for the onset of depression, but little is known about what adolescents can do to reduce their own level of risk. To fill this gap, a review was carried out to identify risk and protective factors for depression during adolescence that are modifiable by the young person. Methods: Employing the PRISMA method, we conducted a systematic review and meta-analysis of longitudinal studies to identify risk and protective factors during the adolescent period (aged 12–18 years) that are potentially modifiable by the young person without professional intervention or assistance. Stouffer׳s method of combining p values was used to determine whether associations between variables were reliable, and meta-analyses were conducted to estimate the mean effect sizes of associations. Results: We identified 113 publications which met the inclusion criteria. Putative risk factors implicated in the development of depression for which there is a sound evidence base, and which are potentially modifiable during adolescence without professional intervention, are: substance use (alcohol, tobacco, cannabis, other illicit drugs, and polydrug use); dieting; negative coping strategies; and weight. Modifiable protective factors with a sound evidence base are healthy diet and sleep. Limitations: Limitations include not systematically reviewing moderators and mediators, the lack of generalisability across cultures or to younger children or young adults, and the inability to conduct a meta-analysis on all included studies. Conclusions: Findings from this review suggest that future health education campaigns or self-help prevention interventions targeting adolescent depression should aim to reduce substance use (alcohol, tobacco, cannabis, other illicit drugs, and polydrug use); dieting; and negative coping strategies; and promote healthy weight; diet; and sleep patterns.