Effects of Transcranial Direct Current Stimulation on Speech and Voice Changes in Parkinson's Disease: a Systematic Review with Meta-Analysis.
Renata Serrano de Andrade Pinheiro, Hercílio Barbosa da Silva Júnior, Bruno Braga Guimarães and 3 others
PMID 41779498WHAT IT FOUND
Combining six small studies, tDCS did not significantly improve speech or voice in Parkinson's.
The overall result was null, with high variability between studies. Do not assume tDCS works for these symptoms based on this evidence.
Key findings
01The overall meta-analysis found no significant effect of tDCS on speech and voice outcomes in Parkinson's disease.
02The certainty of evidence was rated as low due to serious inconsistency and imprecision in the included studies.
03Subgroup analyses showed non-significant results for all target brain areas, including the prefrontal cortex, despite the authors' conclusion that this area had the largest effect size.
STILL TO COME
How it was doneWhat they foundWhat it means for SLPs
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What it does not show
Only six studies were included, and some were case reports or case series with very few participants. The studies used different tDCS targets, intensities, and session numbers, making it hard to compare them directly. The authors claimed the prefrontal cortex had the best effect size, but the statistical test for this subgroup was not significant. One included study was a protocol with no results yet published.
Declared interests
The authors declared no financial support and no conflicts of interest.
The easy way to misread this
Do not interpret the authors' conclusion that the prefrontal cortex showed the best evidence as a proven benefit. The meta-analysis result was null, and the subgroup analysis for the prefrontal cortex was not statistically significant (P=0.17).
Summarised by AI from the full paper, without a clinician reviewing it. Check it against the source before it changes what you do. Read it on PubMed →