Targeting right orbitofrontal cortex (OFC) with transcranial direct current stimulation (tDCS) can improve cognitive executive function in a major depressive episode, but not depressive mood: A Double-blind Randomized Controlled Pilot Trial

Transcranial direct current stimulation (tDCS) has emerged as a potential treatment for major depressive episodes (MDE). This study aimed to evaluate the efficacy of targeting the right orbitofrontal cortex (rOFC) with tDCS in improving depressed mood and cognitive function in patients with depression. A double-blind, ran-domized sham-controlled trial was conducted in which 70 patients with depression were randomly assigned to receive rOFC-tDCS (n = 24), left dorsolateral pre -frontal cortex (lDLPFC) tDCS (n = 23), or SHAM (n = 23). The treatment course consisted of ten treatments (2 mA, 20 min) delivered over two weeks. Participants were then given once-a-week interventions for the next two weeks. The Hamilton Depression Scale 17 evaluated the severity of depressive symptoms, while the cognitive function was assessed using the Stroop Color-Word Test (SCWT) and the Wisconsin Card Sorting Test (WCST). The primary outcomes were evaluated following ten interventions, with the assessment additionally conducted after maintenance treatment and 4-week follow-up visits. Analyses were performed using linear mixed models. The trial was registered with ChiCTR2000034671. The study did not reveal antidepressant efficacy for rOFC-tDCS or lDLPFC-tDCS over SHAM. Cognitive performance improved for rOFC-tDCS and lDLPFC-tDCS compared to sham for response time on the SWCT and non-perseverative errors in the WCST. However, no statistically significant difference was observed between the two active stimulation groups concerning cognitive performance-enhancing effects. No serious adverse events were noted. In conclusion, while rOFC-tDCS did not present advantages for mood outcomes over lDLPFC-tDCS and SHAM, it may have promising effectiveness in cognitive executive function compared to SHAM.