BACKGROUND: While Cogni Behavioral Therapy (CBT) and pharmacotherapy are widely recognized treatments for Major Depressive Disorder (MDD), Dynamic Interpersonal Therapy (DIT) remains underexplored, particularly regarding its long-term effects on symptom reduction, sleep quality, and cognitive functioning. Existing studies rarely compare these approaches across such multidimensional outcomes.
METHODS: In this multi-center randomized controlled trial (MC-RCT), 225 individuals diagnosed with Major Depressive Disorder (MDD) were randomly allocated to one of three structured 16-week treatment conditions comprising Dynamic Interpersonal Therapy (DIT), Cognitive Behavioral Therapy (CBT), or standard pharmacotherapy. The study was conducted across five primary care centers in Iran (Tehran, Tabriz, Shiraz, Isfahan, Mashhad), with follow-ups at 6 and 12 months. Outcomes were measured using the Hamilton Depression Rating Scale (HAM-d-17), Pittsburgh Sleep Quality Index (PSQI), and the Stroop Test. Data were analyzed via Mixed-Design ANOVA.
RESULTS: All three groups showed significant short-term improvements. However, only DIT maintained stable long-term reductions in depressive symptoms (38 %) and sleep disturbances (45 %). DIT also produced superior and lasting gains in cognitive inhibition, selective attention, cognitive flexibility, and processing speed. CBT showed moderate long-term stability, while pharmacotherapy was linked to symptom relapse and diminished cognitive outcomes.
CONCLUSIONS: DIT demonstrates durable, multidimensional benefits in treating MDD, outperforming CBT and pharmacotherapy in sustaining improvements in mood, sleep, and cognition. These findings highlight DIT's potential as a holistic and effective alternative, challenging symptom-focused models and informing future directions in depression care.
