Transcranial Direct/ Alternating Current Stimulation for Parkinson's Disease Treatment

Comparison of Transcranial Direct Current Stimulation and Transcranial Alternating Current Stimulation Treatments in Improving the Motor and Cognitive Performance in Parkinson's Disease

To investigate the difference in the treatment efficacy between transcranial direct current stimulation and transcranial alternating current stimulation on Parkinson's disease, including the improvements in the motor, cognitive, and underlying neural mechanisms behind differences in efficacy by electroencephalography (EEG).

All patients underwent a medical evaluation that include physical examinations and routine laboratory studies before and after stimulation sessions. Patients were randomly allocated to tACS, tDCS, and sham groups. There are about 20 patients in each group. Allocation was by computer generating random numbers. The decision to enroll a patient was always made prior to randomization. Patients were studied using a double-blind design. Study participants, clinical raters, and all personnel responsible for the clinical care of the patient remained masked to allocated conditions and allocation parameters. Only stimulation administrators had access to the randomization list; they had minimal contact with the patients, and no role in assessing the UPDRS(Unified Parkinson´s Disease Rating Scale), Hoehn & Yahr, and MoCA(Montreal Cognitive Assessment). Each patient would be treated for 20 minutes of transcranial electrical stimulation. Before the stimulation session, UPDRS, Hoehn & Yahr, and MoCA were obtained by a trained investigator to assess the baseline severity of symptoms. The patients received electroencephalography (EEG) recorded during resting state for 5 minutes. During the stimulation session, patients were asked to perform simple reaction tasks at the same time. After the stimulation session, UPDRS, Hoehn & Yahr, and MoCA were obtained, as well as the Global Index of Safety（tES slide effects） to assess adverse events of the treatment. The patients also received a measure of electroencephalography (EEG) recorded during the resting state and a simple reaction task.

the alternating current stimulation lasted 20 mins and was delivered at 2mA (peak to peak) at 20Hz during the Simple Reaction Task(SRT), targeting the primary motor cortex. EEG should be acquired before and after the stimulation session.

the direct current stimulation lasted 20 minutes and was delivered at 2mA during the SRT, targeting at the primary motor cortex. EEG should be acquired before and after the stimulation session.

the procedure of this protocol lasted 20 minutes and was delivered at 0mA during the SRT. EEG should be acquired before and after the stimulation session.

used round electrodes（area:3.14cm2） and the montage of a bifrontal setup with C3 as the stimulation electrode, while the return electrode placed on the right shoulder . The dose was at 2mA, 20Hz for 20 minutes.

used round electrodes（area:3.14cm2） and the montage of a bifrontal setup with C3 as stimulation and C4 as return electrodes. The dose was at 2mA for 20 minutes.

used round electrodes（area:3.14cm2） and the montage of a bifrontal setup with C3 as stimulation and C4 as return electrodes. The dose was at 0mA for 20 minutes with the ramp up and down time of 40 seconds.

Unified Parkinson´s Disease Rating Scale Section III-motor is the sum of 18 items, each item contains 0-4 ratings, where 0=normal, 1= slight, 2= mild, 3=moderate, 4=severe.

Montreal Cognitive Assessment is a 30-question test to assess cognitive function. Lower scores mean a worse cognitive status.

First , there was a fixation sign"+" appearing on the screen for 0.5 s, then, after 2-5 seconds, a black dot would appear. Participants were instructed to press the space bar as fast as possible when the black dot appears in the center of the screen, to measure simple perception and sustained alertness. The changes in accuracy(ACC), reaction time(RT), and ACC/RT were calculated.

EEG recording by 8 channels EEG device. The EEG power in alpha， beta， delta, and theta bands will be investigated

Inclusion Criteria: diagnosis of idiopathic PD according to the movement disorder society criteria right-handed no clinically known hearing or vision impairment no history of epilepsy, dementia, other brain disorders apart from PD, severe internal organs disease, age-related frailty, etc. Exclusion Criteria: parkinsonism due to drugs, Cerebrovascular disease, encephalitis, poisoning, traumatic brain injury, etc. Metal implants in the head (i.e., deep brain stimulator or aneurysm clips) severe somatic or psychiatric disorders that require medication or routinely monitoring participated in other interventional studies within the past 3 months