Abstract
Background: Transcranial direct-current stimulation (tDCS) is a neuromodulation with no consensus on its effect in restoring cognitive function following stroke. To determine if dual-site tDCS attenuates post-stroke cognitive impairment and dementia (PSCID), a systematic-review and meta-analysis were carried out. Methods: The available databases were searched until January 2025. Two reviewers conducted study screening, data extraction, and quality assessment separately. The Cochrane Risk Assessment was used to evaluate the risk of bias (ROB). Standard mean difference (SMD) was used as the pooled statistic. Quantitative meta-analysis was performed for domains with at least three studies (aphasia, neglect, attention); other domains (global cognition, executive function, working memory) were assessed qualitatively. Results: The meta-analysis included twelve studies, out of the 17 included in the systematic-review. The qualitative results reported improvements in global cognition, working-memory, and executive-function following tDCS application. The quantitative results demonstrated a pooled effect for aphasia (SMD: 1.965, 95% CI: 0.950-2.979, p<0.001, I²: 82.42%). However, no significant effects were identified for attention (SMD: 1.702, 95% CI: -0.07-3.474, p=0.06, I²: 88.51%) or neglect (SMD: -1.041, 95% CI: -2.209--0.126, p=0.08, I²: 64.73%). Evidence for global cognition, executive-function, and working-memory remains inconclusive due to insufficient studies. Conclusions: Dual-site tDCS may have beneficial effects in PSCID, whit a pooled improvement observed for aphasia. However, no significant effects were found for attention or neglect. Substantial heterogeneity, small sample sizes, and moderate-to-high ROB limit the robustness and generalizability of findings. Overall, current evidence is insufficient to support definitive clinical effectiveness, highlighting the need for high-quality randomized trials.