Combined Effects of tDCS and Language/Cognitive Intervention on the Naming of Dementia Patients: A Systematic Review and Meta-Analysis

Background: The evidence of transcranial direct current stimulation (tDCS) treatment effects on dementia is still insufficient. This study aimed to prove the scientific basis of tDCS by conducting a meta-analysis of previous studies that examined the effects of tDCS on the naming of patients with dementia. Methods: The literature search was conducted for publications published from Jan 2000 to Jun 2019 using four academic databases (PubMed, Web of Science, MEDLINE, and Cochrane Library). This study found 129 publications by searching academic databases according to the PRISMA protocol. Among them, irrelevant studies were excluded, and finally, 4 studies were meta-analyzed. Results: The score of the quality assessment on five studies ranged from 21 to 26 points, rated good or better. Meta-analysis results, tDCS had no significant effect on the improvement of naming ability of dementia. On the other hand, the effect size of the tDCS intervention + language/cognitive training was significant ‘large effect (SMD=0.72, 95% CI: 0.05, 1.39)’. Conclusion: This combination of tDCS and language/cognitive training significantly improved the naming ability of dementia patients.