Efficacy of non-invasive brain stimulation interventions on cognitive impairment: an umbrella review of meta-analyses of randomized controlled trials.
Minmin Wu, Wenjing Song, Xue Wang and 9 others
PMID 39910547WHAT IT FOUND
rTMS improved language and executive function scores in people with dementia or mild cognitive impairment, but evidence quality was low and effects varied widely between patients. tDCS showed no consistent benefit for global cognition, attention, or mood symptoms.
Key findings
01rTMS was associated with statistically significant improvements in global cognition, memory, language, and executive function, though heterogeneity was high and many confidence intervals included null values.
02tDCS showed significant improvements only in memory and executive function in one analysis, while six other associations covering global cognition, attention, language, and neuropsychiatric symptoms were not statistically significant.
03All included meta-analyses were rated as low or very low methodological quality, and none were rated as high quality.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTsWhat it means for SLPs
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What it does not show
All 10 included meta-analyses were rated as low or very low methodological quality, with none rated as high or moderate. High heterogeneity was present in many significant findings, and 50% of significant associations had prediction intervals that included null values, indicating uncertain effects for individual patients. The review combined patients with Alzheimer's disease and mild cognitive impairment, which may mask differences in treatment response between these groups. Stimulation protocols varied widely in electrode placement, intensity, and duration, making it difficult to recommend a specific effective dose. The review relied on existing meta-analyses and did not include the latest high-quality individual randomized controlled trials.
Declared interests
The study was funded by the National Key Research and Development Program of China, the National Natural Science Foundation of China, and the Heilongjiang University of Chinese Medicine Outstanding Cultivation Fund Project. No specific conflicts of interest regarding commercial entities were declared in the provided text.
The easy way to misread this
Do not interpret the significant p-values as proof of a reliable clinical effect. The prediction intervals for many outcomes included zero, meaning that in a new group of patients, the treatment could show no benefit or even harm. Additionally, the methodological quality of every included meta-analysis was rated as low or very low.