In older adults resting-state alpha power is associated with stronger effects of anodal tDCS over prefrontal cortex on dynamic balance.

Abstract

Background: Age-related declines in dynamic balance and cognitive control increase fall risk in older adults (OA). Non-invasive brain stimulation, such as anodal transcranial direct current stimulation (a-tDCS), may enhance training outcomes. However, it remains unclear whether stimulation over motor or prefrontal regions is more effective for improving dynamic balance training (DBT) in OA.

Objective: To compare the effects of a-tDCS over the primary motor cortex (M1) vs. dorsolateral prefrontal cortex (DLPFC) on DBT performance and transfer to static balance in OA, and to explore whether baseline resting-state EEG predicts training outcomes.

Methods: In a randomized crossover design, 18 healthy OA completed DBT training during three stimulation conditions (M1, DLPFC, and sham). Static balance performance was assessed before and after training. Resting-state EEG was recorded to assess predictors of training success.

Results: DBT performance improved significantly more with DLPFC stimulation than with M1 or sham. Negative transfer effects were observed on untrained static balance tasks. Lower baseline alpha power predicted stronger training gains with DLPFC stimulation but weaker gains with M1 stimulation.

Conclusion: DLPFC-targeted a-tDCS enhances DBT in OA more effectively than M1 stimulation. Baseline oscillatory brain activity may inform individualized stimulation protocols to optimize balance training outcomes in OA.