The Impact TDCS-linked Motor and Cognitive Training Gains in Parkinson's Disease

Can Task Specificity and Baseline Outcomes Impact TDCS-linked Motor and Cognitive Training Gains in Parkinson's Disease? a Protocol for a Controlled, Double-blind, Randomized Multicentric Clinical Trial

This study is a group controlled clinical trial. Parallel study, patients aged 40-70 years, with Parkinson disease. Twelve sessions, three times a week, for 30 minutes, simultaneously to the rehabilitation program. Training will consist of Transcranial Direct Current Stimulation linked dual-task exercises or dual-taks exercises with cognitive training, applied three times a week during four weeks. The investigators will used instruments: dual-task gait speed (Auditory Stroop Task ), executive function (Wisconsin Card Sorting Test , Auditory Stroop Test, Trail Making Test, Verbal Fluency Test and Montreal Cognitive Assessment), and, the objective is to examine task-dependency in enhancing the effects of tDCS-linked rehabilitation training on PD and the relationships between baseline outcomes in responders and non-responders to therapy.

Background: Patients with Parkinson's disease have difficulty performing a dual-task, a condition present in everyday life. It is possible that strategies such as Transcranial Direct Current Stimulation can be associated with motor training enriched with dual-task and cognitive training to improve the performance of two concurrent tasks. It is currently unclear whether specific tasks and clinical conditions of PD patients have different results after the intervention. Therefore, the proposed randomized controlled trial will examine task-dependency in enhancing the effects of tDCS-linked rehabilitation training on PD and the relationships between baseline outcomes in responders and non-responders to therapy.

Discussion: This study will evaluate the effectiveness of an intervention protocol with transcranial direct current stimulation, dual-task training and cognitive training in patients with Parkinson's disease. The study will also highlight whether the clinical factors and variability between individuals that could interfere in the training of a specific task and influence the therapeutic effect.

Inclusion Criteria:

• being diagnosed with idiopathic Parkinson's disease by a neurologist based on definitive evidence of responsiveness to levodopa at the start of the disease and the history of progressive hypokinesia with asymmetric onset. PD will be diagnosed based on Parkinson's Disease Society Brain Bank (PDSBB) criteria, as described in Hughes et al.
• age between 40 and 70 years, with no distinction for sex, schooling level or other sociodemographic characteristics
• disease staging between 1.5 and 3, according to the modified Hoehn and Yahr scale
• undergoing regular pharmacological treatment with levodopa (equivalent dose > 300mg) or taking antiparkinsonian medication such as anticholinergics, selegiline, dopamine agonists (amantadine) and COMT (catechol-O-methyl transferase) inhibitors
• score of more than 24 points on the Mini-Mental State Examination
• not exhibiting other associated neurological diseases and no musculoskeletal and/or cardiorespiratory changes that could compromise gait.

Exclusion Criteria:

• be diagnosis of atypical Parkinson's disease
• neuropsychiatric comorbidities; convulsions, metal clips and/or pacemaker; deep brain stimulation implant; history of epilepsy; neurosurgery; traumatic brain injury; alcohol abuse or drug dependency;
• associated diseases of the peripheral or central nervous system
• undergoing physical therapy at another location
• inability to walk 10 meters
• presence of important dyskinesia that prevents the participant from sitting in a chair
• abnormal and persistent increase in systemic blood pressure before or during training, after 3 measurements taken 5 minutes apart - Cut-off: systolic blood pressure ≥ 140 mm Hg and/or diastolic ≥ 90 mm Hg
• not understanding any of the training protocol stages
• chemical scalp treatment within the previous 30 days, and experiencing severe pain and/or discomfort that precludes performing the proposed activities.