Effect of Anodal Transcranial Direct Current Stimulation at the Right Dorsolateral Prefrontal Cortex on the Cognitive Function in Patients With Mild Cognitive Impairment: A Randomized Double-Blind Controlled Trial.

OBJECTIVES:To study the effect of anodal transcranial direct stimulation (atDCS) of the right dorsolateral prefrontal cortex (DLPFC) on cognitive function and side effects in patients with mild cognitive impairment. DESIGN:Experimental double-blind randomized, sham-controlled trial. SETTING:Department of Rehabilitation Medicine, King Chulalongkorn Memorial Hospital PARTICIPANTS: Volunteers (N=45) with mild cognitive impairment. INTERVENTIONS:Not applicable. MAIN OUTCOME MEASURES:The atDCS group (n=23) were stimulated at 2 mA for 20 minutes with the anode on the right DLPFC and the cathode on the left supraorbital area. The control group (n=22) received placebo stimulation. Baseline cognitive function was assessed using the Cambridge Neuropsychological Test Automated Battery test. Participants were treated 3 times per week for 4 weeks (12 sessions). Cognitive function and side effects were assessed immediately after the first stimulation, the last session, and 4 weeks after treatment. RESULTS:Cambridge Neuropsychological Test Automated Battery results revealed a significant improvement in the accuracy of the visual sustained attention (VSA) in the atDCS group at all 3 time points, the spatial working memory and visual memory (VM) immediately after the first stimulation, and a decreased VM reaction time after 12 sessions. A long-lasting effect on VSA and VM were found 4 weeks after treatment. CONCLUSIONS:Anodal tDCS over the right DLPFC enhanced the VSA, spatial working memory, and VM accuracy after the first stimulation and reduced the reaction time of VM after 12 sessions. A long-lasting effect on VSA and VM was found 4 weeks after treatment. This study corroborated atDCS as a safe technique to improve cognitive function.