tDCS for Dual-task Performance 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. Walking performance in a dual-task condition has been used to assess gait automaticity in patients with Parkinson's disease.

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 function. However, few studies have reported the therapeutic effect of tDCS on the dual-task performance in PD. In addition, inconsistent results have been reported because tDCS protocol has been applied in various way. Therefore, this study aims to investigate an optimized stimulation site of tDCS that could improve the dual-task performance in patients with PD.

Inclusion criteria

• Clinically diagnosed as idiopathic Parkinson's disease
• 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
• Sensory abnormalities of the lower extremities, other neurological or orthopedic disease affecting lower extremities, or severe cardiovascular diseases
• Vestibular disease or paroxysmal vertigo
• Pregnant or lactating patients
• Other comorbidities that make it difficult to participate in this study