Asian Journal of Medicine and Health

Background: Transcranial direct current stimulation (tDCS) is a non-invasive neuromodulatory technique that can alter cortical excitability and may influence motor performance. Age-related differences in cortical responses to stimulation during walking remain incompletely characterised.

Aims: To examine cortical changes during single-task and dual-task walking after tDCS, to explore the effect of tDCS on cortical activity, and to examine differences between younger and older adults.

Methodology: Forty-one participants, comprising 23 younger adults and 18 older adults, were randomly allocated to active or sham tDCS groups. Participants completed a 20-minute treadmill walking protocol consisting of normal single-task walking and alternating single- and dual-task walking. Cortical haemodynamic responses were assessed using functional near-infrared spectroscopy (fNIRS), muscle activity using surface electromyography (EMG), and movement using an accelerometer. Active tDCS was delivered using an anodal electrode over the left prefrontal cortex with the inactive cathode over the contralateral eyebrow.

Results: Preliminary analyses showed age-related differences in deoxygenated haemoglobin responses across several cortical regions. Younger adults undergoing active tDCS generally showed decreases in deoxygenated haemoglobin, whereas older adults showed increases across several common regions. During dual-task walking compared with single-task walking, older adults receiving active tDCS showed increases in oxygenated haemoglobin in the right supplementary motor area, right premotor cortex and right primary motor cortex, whereas younger adults showed decreases in these regions.

Conclusion: The preliminary findings indicate that cortical responses to tDCS during walking may differ according to age and task condition. Further statistical analysis is required to determine the significance and clinical relevance of these observed differences.