Introduction: Neuropsychological dysfunctions are a major factor in severe mental disorders, including depression. The present study aimed to investigate the effectiveness of Integrated Neurocognitive Therapy (INT) in improving the neuropsychological functions of individuals with major depressive disorder.

Methods: This research was a quasi-experimental design conducted as a pretest-posttest-3-month follow-up with a control group. 25patients with major depressive disorder referring to psychiatric and rehabilitation clinics in Mashhad were selected by purposive (non-probability) sampling. Data were collected using the Stroop Color-Word Test and Go/No-Go test in the pretest, posttest, and 3-month follow-up phases. Subsequently, the patients in the experimental group underwent Integrated Neurocognitive Therapy for 20 sessions of 90 minutes each (twice a week). Repeated measures analysis of variance and Bonferroni post-hoc test were used for data analysis.

Results: The results showed that the interaction effect between Go/No-Go scores (omission error) and group (F = 2.15, p = 0.148) was not significant, but the interaction effect between Go/No-Go scores (commission error) and group was significant (F = 5.04, p = 0.011). After analyzing the Stroop test data, the results also indicated that the interaction effect between Stroop scores (interference errors) and group (f = 0.90, p = 0.416) was not significant, and the interaction effect between Stroop scores in the subscale (interference time) and group (f = 1.68, p = 0.198) was significant.

Conclusion: Based on the results of this study, Integrated Neurocognitive Therapy can be effective in improving some neuropsychological functions of patients with major depressive disorder and can be used.