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

  • Haewon BYEON Department of Speech Language Pathology, College of Health Science, Honam University, Gwangju, Republic of Korea
Transcranial direct current stimulation;, Dementia;, Naming ability;, 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.



1. Statistics Korea (2017). Statistics on the elderly. Daejeon: Statistics Korea, Korea.
2. Youn H, Jeong H (2018). Pharmacotherapy for dementia. J Korean Med Assoc, 61(12): 758-64.
3. Glosser G, Wolfe N, Albert ML et al (1993). Cross‐cultural cognitive examination: val-idation of a dementia screening instru-ment for neuroepidemiological research. J Am Geriatr Soc, 41(9): 931-9.
4. Murray LL, Clark HM (2015). Neurogenic dis-orders of language and cognition: Evidence-based clinical practice. Austin: Pro-Ed, Texas.
5. Spector A, Orrell M, Hall L (2012). System-atic review of neuropsychological out-comes in dementia from cognition-based psychological interventions. Dement Geri-atr Cogn Disord, 34(3-4): 244-55.
6. Jeong PY, Sung JE, Sim HS (2014). Meta-analysis of cognition-focused interven-tion for people with mild cognitive im-pairment and dementia. CSD, 19(2): 199-212.
7. Freitas C, Mondragón-Llorca H, Pascual-Leone A (2011). Noninvasive brain stim-ulation in Alzheimer's disease: systematic review and perspectives for the future. Exp Gerontol, 46(8): 611-27.
8. Lefaucheur JP, Antal A, Ayache SS et al (2017). Evidence-based guidelines on the therapeutic use of transcranial direct cur-rent stimulation (tDCS). Clin Neurophysiol, 128(1): 56-92.
9. Sebastian R, Tsapkini K, Tippett DC (2016). Transcranial direct current stimulation in post stroke aphasia and primary progres-sive aphasia: Current knowledge and fu-ture clinical applications. NeuroRehabilita-tion, 39(1): 141-52.
10. Costa V, Brighina F, Piccoli T et al (2017). Anodal transcranial direct current stimula-tion over the right hemisphere improves auditory comprehension in a case of dementia. NeuroRehabilitation, 41(2): 567-75.
11. Cotelli M, Manenti R, Petesi M et al (2014). Treatment of primary progressive apha-sias by transcranial direct current stimula-tion combined with language training. J Alzheimers Dis, 39(4): 799-808.
12. Biundo R, Weis L, Fiorenzato E et al (2015). Double-blind randomized trial of t-DCS versus sham in Parkinson patients with mild cognitive impairment receiving cog-nitive training. Brain Stimul, 8(6): 1223-5.
13. André S, Heinrich S, Kayser F et al (2016). At-home tDCS of the left dorsolateral prefrontal cortex improves visual short-term memory in mild vascular dementia. J Neurol Sci, 369: 185-90.
14. Roncero C, Kniefel H, Service E et al (2017). Inferior parietal transcranial direct current stimulation with training improves cogni-tion in anomic Alzheimer's disease and frontotemporal dementia. Alzheimers De-ment (NY), 3(2): 247-53.
15. Lawrence BJ, Gasson N, Johnson AR (2018). Cognitive training and transcranial direct current stimulation for mild cogni-tive impairment in Parkinson’s disease: a randomized controlled trial. Parkinsons Dis, 2018: 4318475.
16. Hung J, Bauer A, Grossman M et al (2017). Semantic feature training in combination with transcranial direct current stimulation (tDCS) for progressive anomia. Front Hum Neurosci, 11: 253.
17. Westwood SJ, Romani C (2017). Transcranial direct current stimulation (tDCS) modula-tion of picture naming and word reading: a meta-analysis of single session tDCS applied to healthy participants. Neuropsy-chologia, 104: 234-49.
18. Stovold E, Beecher D, Foxlee R et al (2014). Study flow diagrams in Cochrane sys-tematic review updates: an adapted PRISMA flow diagram. Syst Rev, 3(1): 54.
19. Kmet LM, Lee R, Cook LS (2004). Standard Quality Assessment Criteria for Evaluating Pri-mary Research Papers from a Variety of Fields. Edmonton: Alberta Heritage Foundation for Medical Research. Canada.
20. Hedges LV, Olkin I (2014). Statistical methods for meta-analysis. Cambridge: Academic press. Massachusetts.
21. Caumo W, Souza IC, Torres IL et al (2012). Neurobiological effects of transcranial di-rect current stimulation: a review. Front Psychiatry, 3: 110.
22. Kim JW, Lee J (2019). Application of Tran-scranial Direct Current Stimulation in Psychiatry. Neuropsychobiology, 24:1-12.
23. Sparing R, Mottaghy FM (2008). Noninva-sive brain stimulation with transcranial magnetic or direct current stimulation (TMS/tDCS)—from insights into human memory to therapy of its dysfunction. Methods, 44(4): 329-37.
How to Cite
BYEON H. Combined Effects of tDCS and Language/Cognitive Intervention on the Naming of Dementia Patients: A Systematic Review and Meta-Analysis. Iran J Public Health. 49(5):822-829.
Review Article(s)