The Effectiveness of Transcranial Direct Current Stimulation (tDCS) on Severity of Obsessive-Compulsive Symptoms, Executive Functions and Rumination in People with Obsessive-Compulsive Symptoms: A Randomized Clinical Trial
Authors: Jahanseir Mohammad , Mousavi Asl Esmaeil , Moghadam Sadegh Amirali , Fakhri Ahmad , Norouzi Shahin 
Published: February 2025

Background: Medical and cognitive treatments for people with obsessive-compulsive symptoms have limitations. Concerns about obsessive-compulsive symptoms arise from evidence indicating that obsessive-compulsive disorder (OCD) can have severe psychological consequences. Objectives: This study aimed to investigate the effectiveness of transcranial direct current stimulation (tDCS) on the severity of obsessive-compulsive symptoms, executive functions, and rumination in individuals with obsessive-compulsive symptoms. Methods: This research was a randomized clinical trial with a pre-and post-test design involving two groups. The statistical population included all individuals with obsessive-compulsive symptoms who referred to the Golestan Hospital Psychiatry Clinic and the Jundishapur University of Medical Sciences Counseling Center in Ahvaz during 2022 - 2023. Thirty individuals who met the inclusion and exclusion criteria were randomly assigned to two groups. In this randomized controlled double-blind study, 30 participants with obsessive-compulsive symptoms (based on the Maudsley Questionnaire cut-off point of 11) were assigned to receive 10 sessions (one session per day) of either active tDCS (2 mA) or sham treatment. Of these, 15 participants received active tDCS, and 15 participants received sham treatment. At the beginning of the study and after the intervention, all subjects were assessed using the Maudsley Obsessional-Compulsive Questionnaire (MOCI), the Executive Functions Questionnaire, the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), and the Mistake Rumination Scale. Data analysis included descriptive statistics and analysis of covariance, performed using SPSS-23 software. Results: In the pre-test, the mean scores of MOCI, Y-BOCS, mistake rumination, and executive functions in the active tDCS group were 22.40 ± 2.09, 22.33 ± 7.72, 20.93 ± 4.16, and 86.40 ± 14.38, respectively, compared to 21.53 ± 1.80, 20.33 ± 6.89, 19.13 ± 5.34, and 83.06 ± 16.61 in the sham treatment group. In the post-test, the mean scores in the active tDCS group were 14.46 ± 3.06, 14.40 ± 2.99, 11.46 ± 2.13, and 102.86 ± 8.40, respectively, compared to 21.66 ± 1.54, 18.13 ± 6.99, 18.26 ± 4.89, and 86.93 ± 15.54 in the sham treatment group. Results showed that the active tDCS group exhibited a significantly greater reduction in obsessive-compulsive symptoms and rumination and a significant improvement in executive functions compared to the sham treatment group (P < 0.05). Conclusions: The tDCS appears to have a significant effect on reducing obsessive-compulsive symptoms and rumination and improving executive functions in individuals with obsessive-compulsive symptoms. Longer treatment durations with a higher number of tDCS sessions may be necessary to achieve clinically significant responses. Additionally, determining the optimal electrode placement for OCD remains a critical and challenging issue.