Abstract 7: Dose Response Relationship in Transcranial Direct Current Stimulation Stroke Motor Recovery Studies
Background: Dozens of clinical trials investigated the potential efficacy of transcranial direct current stimulation (tDCS) in post-stroke motor recovery. Various current levels, pad size, number of sessions were used in different studies with mixed results in motor outcomes. We aimed to investigate a dose/current-response relationship by pooling published studies.
Methods: We identified relevant studies in Pubmed, EMBASE and clinicaltrials.gov from January 1990 to June 2014. We included sham-controlled randomized or quasi-randomized studies with ≥5 tDCS sessions and derived percent improvement in primary endpoint (percent improvement in treatment group - percent improvement in sham group) from each study. We plotted current, current density, charge per session, charge density per session, total charge and charge density with percent improvement. To assess the dose-response relationship, we conducted regression analyses where studies were weighed by the number of participants (sample size).
Results: We identified 8 studies with 272 subjects in total comparing active stimulation (anodal, cathodal or bi-hemispheric) with sham stimulation in terms of motor improvement. Pooling the results from these studies shows a positive dose/current-response relationship. Pearson’s correlation coefficients between percent improvement and current, current density, charge per session, charge density per session, total charge and charge density are –0.12, 0.2, 0.15, 0.27, 0.34 and 0.21, respectively.
Conclusion: By pooling studies, a dose response relationship is revealed and is best demonstrated by charge density per session. Phase II trials may be considered to formally assess this relationship in stroke patients towards determination of optimal dose in large clinical trials.
Author Disclosures: W. Feng: Research Grant; Significant; American Heart Association SDG, NIH, Halo Neuroscience InC. J.A. Enabore: None. S. Kautz: Employment; Significant; VA. Research Grant; Significant; NIH. R.J. Adams: Research Grant; Significant; NIH, DOD. P. Chhatbar: None.
- © 2015 by American Heart Association, Inc.