Self-administered tDCS for Improving Single- and Dual-task Gait in Patients With PD

Parkinson's disease (PD) is a disease caused by dopamine deficiency in the striatum resulting from the loss of dopaminergic neuronal cells in the cerebral substantia. It is a progressive neurodegenerative disease characterized by motor symptoms including gait disturbance and balance instability. In the early stages of Parkinson's disease, dysfunction of the sensorimotor area of the basal ganglia typically occurs, leading to habitual control hurdles. Accordingly, cognitive efforts are required to perform habitual tasks such as walking, and the automaticity of walking is reduced. Dual-task performance involves a complex interplay of motor functions as well as cognitive functions such as attention and executive function. One way to potentially reduce the cost of dual-tasking and the negative effects of motor-cognitive interference is to consider improving the corresponding component, i.e., motor or cognitive function.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation method that can be used to change cortical activity. Recently, there has been growing attention on tDCS as an adjunct tool for rehabilitation. Several tDCS studies in patients with PD have reported the positive results of tDCS on motor and cognitive function. Most studies have examined changes before and after a single session of stimulation, with limited research verifying the cumulative and long-term effects of tDCS. Therefore, this study aims to investigate the efficacy and safety of self-administered transcranial direct current stimulation to improve the single- and dual-task gait in patients with PD.

Inclusion criteria

• Clinically diagnosed as idiopathic Parkinson's disease by neurologists according to the UK Parkinson's Disease Society Brain Bank criteria
• modified Hoehn & Yahr stage 2, 2.5, or 3

Exclusion criteria

• History of seizure
• Metallic implants, such as cardiac pacemaker or an artificial cochlea
• Patients with inflammation, burns, or wounds in the stimulation area
• Parkinson's disease dementia; cut-off is < 7 of Korean-Montreal Cognitive Assessment for illiterate patients, < 13 for those educated for 0.5-3 years, < 16 for 4-6 years of education, < 19 for 7-9 years of education, and < 20 for 10 or more years of education.
• Severe dyskinesia or severe on-off phenomenon
• Plan to adjust medication at the time of screening
• Other neurological, orthopedic, or cardiovascular co-morbidities significantly affecting gait function
• Uncontrolled vestibular disease, orthopedic hypotension, or paroxysmal vertigo
• Pregnant or lactating patients
• Other comorbidities that make it difficult to participate in this study