The effects of consecutive sessions of anodal transcranial direct current stimulation over the primary motor cortex on hand function in healthy older adults

Background: With advancing age, changes in the central nervous system may lead to motor functional deficits. Non-invasive brain stimulation techniques are suggested to help modifying brain function. Objectives: The aim of the current study was to investigate the effect of using multi session anodal transcranial Direct Current Stimulation (a-tDCS) over the primary motor cortex (M1) on the hand function in healthy older adults. Method: In this randomized, double-blinded, sham-controlled study 32 participants received active or sham a-tDCS (1 mA, 20 min, for five consecutive days) and performed the Purdue Pegboard Test (PPT) on the first day before tDCS application, immediately (T1), 30 min (T2), and one week after the last session (5th day) (T3) of the stimulation. Results: There was a significant improvement for PPT (p < 0.05) in a-tDCS group at all post-test values except for PPT for left hand (PPTL) at T1. Compared to the sham group, the results indicated significant improvement in all PPT subtests (P < 0.05), except for PPTL at T1, PPT for both hands at T2 and PPT assembly at T3 in a-tDCS group. Conclusion: The current findings suggest a-tDCS can be considered as a promising stand-alone technique in the intervention of the age-related decline of manual dexterity for improving hand function.