Evaluating the effectiveness of transcranial direct current stimulation on improving cognitive function in bipolar patients

Abstract

Background: Bipolar disorder is classified as one of the most debilitating mental diseases. Although patients receive medical treatment, cognitive deficits remain in the euthymic phase in many patients. It is hypothesized that brain electrical stimulation protocols that increase cognitive function may increase the quality of life. Therefore, this study aimed to evaluate the effectiveness of transcranial direct current stimulation in improving cognitive function in bipolar patients in the euthymic phase. Methods & Materials: In a double-blind, sham-controlled- clinical trial, 46 euthymic bipolar patients diagnosed based on DSM-V were randomly divided into the two intervention and control groups. tDCS was applied for the intervention group using an anode electrode at the left dorsolateral-peripheral cortex (F3) and the cathode at the right dorsolateral-frontal (F4) (based on the 10/20 system) at 2 mA for 20 min. The Strop Color and Word Test, The Rey Auditory Verbal Learning Test (RAVLT), and The Wechsler Adult Intelligence Scale (WAISR) were evaluated before, at the end of the third and the seventh weeks of the intervention. Statistical analysis was performed using SPSS v 16. Results: The scores of immediate and delayed auditory memory and visual memory in the intervention group, unlike the control group, improved significantly after treatment. Moreover, Wechsler's working memory score in the intervention group improved significantly after treatment. Consistent and inconsistent answers scores were also significantly improved in the intervention group compared with the controls. Conclusion: The present study indicated that tDCS might be an efficient and safe method for improving cognitive function in euthymic bipolar patients.

Keywords

• Bipolar disorder
• Transcranial direct current stimulation (tDCS)
• Cognitive functions