tDCS for 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