Identifying Candidate Mediators Linking ADHD Symptoms and Internalising Problems in Adolescence: An Exploratory Longitudinal Mediation Analysis

OBJECTIVE: ADHD and internalising symptoms such as anxiety and depression are known to be associated in adolescence and understanding the mechanisms linking them is important for improving mental health outcomes for adolescents with ADHD symptoms. Our objective was to examine these mechanisms. METHOD: = 2,791 female) to simultaneously evaluate a range of hypothesised mediating mechanisms. These include indirect effects via peer problems, conduct problems, self-esteem, injuries and accidents, relationships with parents, academic performance, risky decision-making, parental mental health, educational motivation, and general health. We used exploratory longitudinal mediation analysis with regularised structural equation modelling (regSEM) to examine 14 candidate mediators of the ADHD-internalising association across ages 11, 14 and 17. RESULTS: Regularisation with lasso did not result in the de-selection of any of these mediators; however, only two were statistically significant. CONCLUSION: Results suggest there may be many mediators of small effect involved in the relation between ADHD symptoms and later internalising problems but point to self-esteem and parental mental health as priority mechanisms for further study in future causal and interventional research.