Temporal relationships between changes in depression and suicidal ideation: A mediation analysis in a randomized double‐blinded clinical trial

OBJECTIVES: There is a considerable debate regarding the possible dependence between depression and suicidal ideation treatments. The present study used a novel mediation approach in a randomized comparison of pharmacotherapy and combined therapy to explore whether depressive symptoms mediate the association between treatment and suicidal ideation and whether it depends on the treatment condition. DESIGN: This study is a randomized, controlled, parallel group (1:1), clinical trial using a novel mediation approach for longitudinal data. Latent difference score modelling was utilized to investigate whether changes in depressive symptoms drive subsequent changes in suicide ideation. METHOD: Participants were 94 depressive suicidal outpatients who were assessed regarding depressive symptoms and suicidal ideation over the course of an experiment (0-2-7 months). Direct and indirect associations between (change in) depressive symptoms and (change in) suicidal ideation were explored using Pearson's correlations and latent difference score model. RESULTS: The results showed that depression treatment affects not only suicidal ideation directly but also its influence on suicidal ideation occurs via improvement in depressive symptoms. It was found a more significant effect of combining pharmacotherapy and PPT (in comparison with the pharmacotherapy alone) on the early and late improvements of suicidal ideation (Δ 0-2 and Δ 2-7) via the early improvement of depressive symptoms (Δ 0-2). CONCLUSIONS: The findings indicate that changes in depressive symptoms preceded changes in suicidal ideation. Our results highlighted that improving depressive symptoms could be a primary target in treating patients with depression experiencing suicidal thoughts.