Background Progression of Parkinson's disease (PD) is characterised by motor deficits which eventually respond less to dopaminergic therapy and thus pose a therapeutic challenge. Deep brain stimulation has proven efficacy but carries risks and is not possible in all patients. Non-invasive brain stimulation has shown promising results and may provide a therapeutic alternative.
Objective To investigate the efficacy of transcranial direct current stimulation (tDCS) in the treatment of PD.
Design Randomised, double blind, sham controlled study.
Setting Research institution.
Methods The efficacy of anodal tDCS applied to the motor and prefrontal cortices was investigated in eight sessions over 2.5 weeks. Assessment over a 3 month period included timed tests of gait (primary outcome measure) and bradykinesia in the upper extremities, Unified Parkinson's Disease Rating Scale (UPDRS), Serial Reaction Time Task, Beck Depression Inventory, Health Survey and self-assessment of mobility.
Results Twenty-five PD patients were investigated, 13 receiving tDCS and 12 sham stimulation. tDCS improved gait by some measures for a short time and improved bradykinesia in both the on and off states for longer than 3 months. Changes in UPDRS, reaction time, physical and mental well being, and self-assessed mobility did not differ between the tDCS and sham interventions.
Conclusion tDCS of the motor and prefrontal cortices may have therapeutic potential in PD but better stimulation parameters need to be established to make the technique clinically viable.
This study was publicly registered (clinicaltrials.org: NCT00082342).
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Funding This research was supported by the Intramural Research Program of the NINDS, NIH and in part by a grant from the USAMRMC (W81XWH-06-1-0534).
Competing interests MH has received personal compensation or travel expenses for activities with Neurotoxin Institute, John Templeton Foundation, Parkinson's and Ageing Research Foundation, University of Pennsylvania, Thomas Jefferson University, Baylor College of Medicine, American Academy of Neurology, Medical University of South Carolina, Northshore-Long Island Jewish Hospital, American Clinical Neurophysiology Society, Columbia University, University of Alabama, Blackwell Publisher, Cambridge University Press, Springer Verlag, Taylor and Francis Group, Oxford University Press, John Wiley and Sons and Elsevier as an advisory board member, an editor, a writer or a speaker. MH has received licence fee payments from the National Institutes of Health for the H-coil, a type of coil for magnetic stimulation. MH and his wife held stock in Agilent Technologies, Amgen, Amylin Pharmaceuticals, Merck and Co, Monsanto Co New Del, Sanofi Aventis Adr, Coventry Health Care Inc, Sigma Aldrich Corp, Warner Chilcott Ltd, Pfizer Inc, Genentech, Inc, United Health Group, St Jude Medical and Eli Lilly and Company.
Ethics approval This study was conducted with the approval of the Institutional Review Board, NINDS, NIH.
Provenance and peer review Not commissioned; externally peer reviewed.
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