Transcranial Direct Current Stimulation for Parkinson's Disease: A Systematic Review and Meta-Analysis

Background: Parkinson's disease is a common neurodegenerative disorder with motor and non-motor symptoms. Recently, as adjuvant therapy, transcranial direct current stimulation (tDCS) has been shown to improve the motor and non-motor function of patients with Parkinson's disease (PD). This systematic review aimed to evaluate the existing evidence for the efficacy of tDCS for PD. We included English databases (PubMed, the Cochrane Library, Embase, and Web of Science) and Chinese databases [Wanfang database, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), and China Biology Medicine (CBM)] without restricting the year of publication. Twenty-one tDCS studies, with a total of 736 participants, were included in the analysis. Two independent researchers extracted the data and characteristics of each study. There was a significant pooled effect size (−1.29; 95% CI = −1.60, −0.98; p < 0.00001; I2 = 0%) in the Unified PD Rating Scale (UPDRS) I and the Montreal cognitive assessment (SMD = 0.87, 95% CI = 0.50 to 1.24; p < 0.00001; I2 = 0%). The poor effect size was observed in the UPDRS III scores (SMD = −0.13; 95% CI = −0.64, 0.38; p = 0.61; I2 = 77%), and similar results were observed for the timed up and go (TUG) test, Berg balance scale, and gait assessment. The results of this meta-analysis showed that there was insufficient evidence that tDCS improves the motor function of patients with PD. However, tDCS seemed to improve their cognitive performance. Further multicenter research with a larger sample size is needed. In addition, future research should focus on determining the tDCS parameters that are most beneficial to the functional recovery of patients with PD.

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Does transcranial direct current stimulation improve functional locomotion in people with Parkinson’s disease? A systematic review and meta-analysis

Journal of NeuroEngineering and Rehabilitation ◽

10.1186/s12984-019-0562-4 ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 3

Author(s):

Hyo Keun Lee ◽

Se Ji Ahn ◽

Yang Mi Shin ◽

Nyeonju Kang ◽

James H. Cauraugh

Keyword(s):

Systematic Review ◽

Parkinson’S Disease ◽

Parkinson's Disease ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Meta Analysis ◽

Direct Current Stimulation

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Transcranial Direct Current Stimulation to Enhance Cognitive Impairment in Parkinson's Disease: A Systematic Review and Meta-Analysis

Frontiers in Neurology ◽

10.3389/fneur.2020.597955 ◽

2020 ◽

Vol 11 ◽

Author(s):

Diana M. A. Suarez-García ◽

Johan S. Grisales-Cárdenas ◽

Máximo Zimerman ◽

Juan F. Cardona

Keyword(s):

Systematic Review ◽

Parkinson’S Disease ◽

Parkinson's Disease ◽

Direct Current ◽

Cognitive Deficits ◽

Transcranial Direct Current Stimulation ◽

Meta Analysis ◽

Direct Current Stimulation ◽

Positive Effects ◽

Cognitive Improvement

Cognitive deficits are increasingly being recognized as a common trait in Parkinson's disease (PD). Recently, transcranial direct current stimulation (tDCS) has been shown to exert positive effects as an adjunctive therapy on motor and non-motor symptoms in PD. This systematic review and meta-analysis aims to provide an overview of reported evidence on the efficacy of tDCS interventions in the treatment of cognitive impairments in PD. A systematic literature review was conducted to examine articles that were published in the past 10 years and that study the effects of tDCS on cognitive deficits in PD patients. The PubMed, Scopus and Scielo databases were searched. Eight tDCS studies involving 168 participants were included for the analysis. Our meta-analysis results showed that anodal tDCS (atDCS) had various levels or no evidence of effectiveness. In the pre-post stimulation analysis, a strong effect was reported for executive functions (pre-post: g = 1.51, Z = 2.41, p = 0.016); non-significant effects were reported for visuospatial skills (pre-post: g = 0.27, Z = 0.69, p = 0.490); attention (pre-post: g = 0.02, Z = 0.08, p = 0.934), memory (pre-post: g = 0.01, Z = 0.03, p = 0.972) and language (pre-post: g = 0.07, Z = 0.21, p = 0.832). However, in the pre-follow-up stimulation analysis, the duration of the effect was not clear. This study highlights the potential effectiveness of atDCS to improve cognitive performance in PD patients but failed to establish a cause-effect relationship between tDCS intervention and cognitive improvement in PD. Future directions and recommendations for methodological improvements are outlined.

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Transcranial Direct Current Stimulation on Parkinson's Disease: Systematic Review and Meta-Analysis

Frontiers in Neurology ◽

10.3389/fneur.2021.794784 ◽

2022 ◽

Vol 12 ◽

Author(s):

Paloma Cristina Alves de Oliveira ◽

Thiago Anderson Brito de Araújo ◽

Daniel Gomes da Silva Machado ◽

Abner Cardoso Rodrigues ◽

Marom Bikson ◽

...

Keyword(s):

Systematic Review ◽

Parkinson’S Disease ◽

Parkinson's Disease ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Meta Analysis ◽

Motor Fluctuations ◽

Motor Symptoms ◽

Z Score ◽

Direct Current Stimulation

Background: Clinical impact of transcranial direct current stimulation (tDCS) alone for Parkinson's disease (PD) is still a challenge. Thus, there is a need to synthesize available results, analyze methodologically and statistically, and provide evidence to guide tDCS in PD.Objective: Investigate isolated tDCS effect in different brain areas and number of stimulated targets on PD motor symptoms.Methods: A systematic review was carried out up to February 2021, in databases: Cochrane Library, EMBASE, PubMed/MEDLINE, Scopus, and Web of science. Full text articles evaluating effect of active tDCS (anodic or cathodic) vs. sham or control on motor symptoms of PD were included.Results: Ten studies (n = 236) were included in meta-analysis and 25 studies (n = 405) in qualitative synthesis. The most frequently stimulated targets were dorsolateral prefrontal cortex and primary motor cortex. No significant effect was found among single targets on motor outcomes: Unified Parkinson's Disease Rating Scale (UPDRS) III – motor aspects (MD = −0.98%, 95% CI = −10.03 to 8.07, p = 0.83, I2 = 0%), UPDRS IV – dyskinesias (MD = −0.89%, CI 95% = −3.82 to 2.03, p = 0.55, I2 = 0%) and motor fluctuations (MD = −0.67%, CI 95% = −2.45 to 1.11, p = 0.46, I2 = 0%), timed up and go – gait (MD = 0.14%, CI 95% = −0.72 to 0.99, p = 0.75, I2 = 0%), Berg Balance Scale – balance (MD = 0.73%, CI 95% = −1.01 to 2.47, p = 0.41, I2 = 0%). There was no significant effect of single vs. multiple targets in: UPDRS III – motor aspects (MD = 2.05%, CI 95% = −1.96 to 6.06, p = 0.32, I2 = 0%) and gait (SMD = −0.05%, 95% CI = −0.28 to 0.17, p = 0.64, I2 = 0%). Simple univariate meta-regression analysis between treatment dosage and effect size revealed that number of sessions (estimate = −1.7, SE = 1.51, z-score = −1.18, p = 0.2, IC = −4.75 to 1.17) and cumulative time (estimate = −0.07, SE = 0.07, z-score = −0.99, p = 0.31, IC = −0.21 to 0.07) had no significant association.Conclusion: There was no significant tDCS alone short-term effect on motor function, balance, gait, dyskinesias or motor fluctuations in Parkinson's disease, regardless of brain area or targets stimulated.

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Correction to: Does transcranial direct current stimulation improve functional locomotion in people with Parkinson’s disease? A systematic review and meta-analysis

Journal of NeuroEngineering and Rehabilitation ◽

10.1186/s12984-019-0582-0 ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 1

Author(s):

Hyo Keun Lee ◽

Se Ji Ahn ◽

Yang Mi Shin ◽

Nyeonju Kang ◽

James H. Cauraugh

Keyword(s):

Systematic Review ◽

Parkinson’S Disease ◽

Parkinson's Disease ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Meta Analysis ◽

Direct Current Stimulation ◽

Study Characteristics

In the original article [1], we mentioned that some study characteristics of the article by Dagan and colleagues [2] were unavailable.

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The effects of transcranial direct current stimulation on gait in patients with Parkinson’s disease: a systematic review

Translational Neurodegeneration ◽

10.1186/s40035-021-00245-2 ◽

2021 ◽

Vol 10 (1) ◽

Author(s):

Fateme Pol ◽

Mohammad Ali Salehinejad ◽

Hamzeh Baharlouei ◽

Michael A. Nitsche

Keyword(s):

Systematic Review ◽

Parkinson’S Disease ◽

Parkinson's Disease ◽

Direct Current ◽

Transcranial Direct Current Stimulation ◽

Randomized Clinical Trials ◽

Cortical Excitability ◽

Experimental Studies ◽

Gait Rehabilitation ◽

Direct Current Stimulation

Abstract Background Gait problems are an important symptom in Parkinson’s disease (PD), a progressive neurodegenerative disease. Transcranial direct current stimulation (tDCS) is a neuromodulatory intervention that can modulate cortical excitability of the gait-related regions. Despite an increasing number of gait-related tDCS studies in PD, the efficacy of this technique for improving gait has not been systematically investigated yet. Here, we aimed to systematically explore the effects of tDCS on gait in PD, based on available experimental studies. Methods Using the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) approach, PubMed, Web of Science, Scopus, and PEDro databases were searched for randomized clinical trials assessing the effect of tDCS on gait in patients with PD. Results Eighteen studies were included in this systematic review. Overall, tDCS targeting the motor cortex and supplementary motor area bilaterally seems to be promising for gait rehabilitation in PD. Studies of tDCS targeting the dorosolateral prefrontal cortex or cerebellum showed more heterogeneous results. More studies are needed to systematically compare the efficacy of different tDCS protocols, including protocols applying tDCS alone and/or in combination with conventional gait rehabilitation treatment in PD. Conclusions tDCS is a promising intervention approach to improving gait in PD. Anodal tDCS over the motor areas has shown a positive effect on gait, but stimulation of other areas is less promising. However, the heterogeneities of methods and results have made it difficult to draw firm conclusions. Therefore, systematic explorations of tDCS protocols are required to optimize the efficacy.

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