The Effect of Transcranial Direct Current Stimulation (tDCS) on Attentional Bias and Affect in Adults with Major Depressive Disorder (MDD)

Individuals with MDD have deficits in "hot" cognition such as attentional bias to negative stimuli.They also experience low levels of positive and high levels of negative affect.This study aimed to investigate the effects of transcranial direct current stimulation (tDCS) on the ventromedial prefrontal cortex (vmPFC) and dorsolateral prefrontal cortex (dlPFC) on attentional bias and affective state in patients with major depressive disorder. The present research had a single-blinded, crossover design.Twenty-three adults with MDD received tDCS in three separate sessions with different montages: anodal dlPFC (F3)/ cathodal vmPFC (Fp2), the reversed montage and sham.Their performance was evaluated by dot- probe test (online) and PANAS questionnaire(Pre-Post Stimulation). There was no significant difference between different montages of tDCS on attentional bias in depressed patients. However, a significant difference was observed in the negative affect (p<0/05). Attentional bias is a form of hot cognition and affects MDD patients. The present study showed no significant difference in the attentional bias scores between the three tDCS montages. However, results showed that anodal stimulation of DLPFC and cathodal stimulation of VMPFC improved the affective state of patients with MDD by reducing the levels of the negative affect.