Effects of primed anodal transcranial direct current stimulation on the psychomotor function of older adults

Declines in cognitive and motor functions as a result of ageing have an adverse impact on the quality of life. One such decline takes the form of poorer psychomotor performance, which involves both cognitive and motor processes in terms of perceiving and processing external stimuli, and executing motor responses. Recent research using transcranial direct current stimulation (tDCS) has shown that priming the corticospinal system by lowering the threshold for the induction of long-term potentiation facilitates subsequent motor performance. Here we utilised this priming approach in a double-blind sham-controlled experiment to investigate the efficacy of the application of tDCS to the dorsolateral prefrontal cortex (DLPFC) in improving the psychomotor performance of older adults. A group of 10 healthy older individuals (mean age 71.60 years; 5 males and 5 females) participated in 2 sessions on separate days, with 1 session involving a 10-minute cathodal tDCS followed by a 20-minute anodal tDCS (C-A), and the other involving a 10-minute cathodal tDCS followed by sham stimulation (C-S) over the left DLPFC. Psychomotor performance was determined through the accuracy and response speeds on a task measuring sustained, selective, and divided attention. The accuracy scores for divided attention were significantly higher in the C-A condition compared with the C-S condition, suggesting that anodal tDCS primed with cathodal tDCS is effective in improving divided attention, and shows promise as a clinical intervention for improving psychomotor function in older adults