Efficacy and Safety of Transcranial Direct Current Stimulation on Multiple Health Outcomes in Neurological Disorders: An Umbrella Review of Meta-Analyses of Randomized Controlled Trials.

BACKGROUND

Neurological disorders are a leading cause of disability worldwide. Transcranial direct current stimulation (tDCS) is a promising therapeutic tool for neurological disorders. However, a consensus on clinical recommendations for using tDCS in patients with neurological disorders is lacking. In this umbrella review, we aimed to establish evidence-based guidance for using tDCS to treat neurological disorders.

METHODS

This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines 2020. PubMed/MEDLINE, Embase, the Cochrane Library, the Web of Science, and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) were systematically searched to identify and evaluate existing systematic reviews and meta-analyses on the use of tDCS for neurological disorders. Quality was assessed using the Measurement Tool to Assess Systematic Reviews 2 (AMSTAR 2) and the Grades of Recommendations, Assessment, Development, and Evaluation (GRADE) tool. The Hartung-Knapp-Sidik-Jonkman random effects model was employed for reanalysis.

RESULTS

A total of 17 systematic reviews and meta-analyses encompassing 358 randomized controlled trials and 7160 participants were analyzed. tDCS demonstrated efficacy across seven distinct health conditions, including stroke, Parkinson's disease, Alzheimer's disease, cerebellar ataxia, fibromyalgia, disorders of consciousness, and migraine. Adverse effects were rarely reported, with the exception of mood changes associated with fibromyalgia. Our results indicated that tDCS significantly improved 34 distinct health outcomes related to these conditions.

CONCLUSIONS

We found that tDCS may be a promising treatment for neurological disorders, with mild and infrequent adverse effects. Further studies are warranted to validate the therapeutic potential of tDCS in the reported neurological conditions, investigate additional neurological health outcomes, and explore the underlying mechanisms of tDCS effects. The PROSPERO Registration: CRD42024589432, https://www.crd.york.ac.uk/PROSPERO/view/CRD42024589432.