The present study aimed to investigate the effectiveness of psycho neurocognitive therapy on reduction of clinical symptoms and improvement of executive function (behavioral regulation and meta-cognition) in patients with major depression. The research method was conducted as a case study with a multiple baseline design. The study population included all patients referred to psychiatric and clinical psychology treatment centers in Mashhad with a diagnosis of major depression which among those 6 cases were selected through purposeful sampling who underwent psycho neurocognitive therapy for 12 sessions. The research tools included the Beck Depression Inventory (BDI-II), Hamilton Depression Rating Scale (HDRS), Depression, Anxiety, Stress Scale (DASS), and Function Executive of Inventory Rating Behavior (BRIEF-A). Data were analyzed using graphical and pictorial analysis, percentage improvement indices, effect size, and Cohen's d. The results showed that psycho neurocognitive therapy significantly reduced clinical symptoms and improved executive functions (behavioral regulation and metacognition) in patients with major depression. The findings of this study indicate that psycho neurocognitive therapy can be used as an effective approach in improving the cognitive and psychological aspects of patients with major depression.
