Limitations
Our study has several limitations that should be discussed. First, the sample size was small. Thus, some analyses might have been underpowered, and future studies should use these results as hypothesis-driven. Second, other anatomical measures such as cortical volume could have been used for this study. However, as a previous study suggests that cortical thickness could be associated with tDCS response, and other studies with elderly show that cortical thickness is more sensitive to investigate response confounders (i.e., age and sex) (