The Effects of Transcranial Direct Current Stimulation on Cognition Skills after Stroke

Background and Aim: treatment of cognition skills after stroke is important factor and is one of the novel issue in speech and language pathology. Materials and Methods: We conducted a search in PMC, Web of Science, PubMed, Scopus, Medline, SID, Google Scholar and Ovid databases. The present information is available reviewing the articles from ۱۹۹۶ to ۲۰۲۰ through the search of the resources. Results: Strokes can adversely affect vision, balance, cognition, memory and speech. Many stroke patients have reduced speaking abilities, called aphasia. We included ۲۰ studies involving a total of ۴۰۸ participants aged above ۱۸ with acute, postacute or chronic ischemic or hemorrhagic stroke. Some patients had pricking sensation at the sites of stimulation after the tDCS but there were no notable side effects. The risk of bias did not differ substantially for different comparisons and outcomes. We found four studies with ۱۹۶ participants examining the effects of tDCS versus sham tDCS. two studies with ۶۹ participants assessed the effects of tDCS on ADLs at the end of follow-up, and found improved ADL performance. However, this effect may be underestimated due to reporting bias. In one study After intervention, all patients had significant improvements in aphasia quotients, spontaneous speech, and auditory verbal comprehension. However, auditory verbal comprehension improved significantly more in patients treated with a cathode, as compared to patients in the other groups. In another study In the line bisection test, significant improvements were observed after both the dual- and the single-mode tDCS (p<۰.۰۵), but not after sham stimulation. Statistical analysis showed a significant interaction between time and tDCS mode, where the dual tDCS had a stronger effect than the single or sham stimulation modes (p<۰.۰۵). The star cancelation test did not show any significant change. Conclusion: Speech therapy methods can improve brain synaptic plasticity. The aim of therapy is to recover as much of speech as possible and/or find alternative ways of communicating. The tDCS is a safe and effective neuro-rehabilitation modality that improves post stroke cognitive dysfunctions. Moreover, tDCS has a positive impact on performance of daily activities. our results demonstrated the beneficial effects of anodal tDCS on memory function. Noninvasive anodal tDCS applied to the left DLPFC was found to improve attention versus sham stimulation in stroke patients, which suggests that non-invasive cortical intervention could potentially be used during rehabilitative training to improve attention. This suggests that the degree of attention can be significantly improved with the application of the tDCS to the prefrontal cortex in patients with stroke. Our results also demonstrated that anodal transcranial direct current stimulation over the left dorsolateral prefrontal cortex enhanced working memory performance as indexed by the recognition accuracy in patients after a stroke. However, there are many ongoing randomized trials that could change the quality of evidence in the future. Future studies should particularly engage those who may benefit most from tDCS after stroke and in the effects of tDCS on upper and lower limb function, muscle strength and cognitive abilities (including spatial neglect).

Keywords:

Cognition , Speech & , language pathology , Stroke , TDCS