Effect of Transcranial Direct Current Stimulation on Auditory-Verbal Memory in Healthy Elderly

Background and purpose: Auditory-verbal memory decreases with age. One method to compensate this weakness is transcranial direct current stimulation. The current study investigated the effect of Anodal Transcranial Direct Current Stimulation on auditory-verbal memory performance of healthy elderly people. Materials and methods: In a randomized clinical trial, 42 healthy subjects with no history of cognitive problems were divided into experimental and control groups (n=21 per group). All participants received 10 sessions of electrical stimulation at 2 mA. In order to evaluate the auditory-verbal memory of the subjects, the Persian version of the Rey Auditory Verbal Learning Test (RAVLT) was used before and after electrical current delivery. Results: In experimental group, the mean scores for all stages of the RAVLT, were found to be significantly different after electrical stimulation compared to those before stimulation (P<0.05). Also, the mean scores for all stages of the RAVLT showed significant differences between the control group and experimental group after electrical stimulation (P< 0.05) except in the reminder stage after the intervention (P= 0.075).  Conclusion: Anodal Transcranial Direct Current Stimulation affects the electrical potential of nerve cells membrane in the dorsolateral prefrontal cortex (DLPFC) and increases neural activity of nerve cells in that area, which can lead to improvements in auditory-verbal memory.