This clinical trial aims to study whether transcranial alternating current stimulation (tACS) applied to the medial frontal cortex (MFC) can improve speech and cognitive function in people with Parkinson's disease (PD), and to evaluate the safety of tACS. The main goals are to answer the following questions: 1. Can tACS stimulation of the MFC improve executive functions in people with PD (such as reasoning, planning, inhibition, and complex problem-solving)? 2. Can it improve the integration of auditory information and speech motor control during communication? Researchers will compare the effects of real tACS versus sham (placebo) stimulation to see if real stimulation leads to better speech and cognitive outcomes in PD patients. Participants will: 1. Receive one extra 20-minute session of either real or sham tACS each day for two weeks 2. Attend clinic visits before stimulation, right after the 2-week period, and again at 1 month and 3 months for assessments and tests 3. Have their executive function scores, speech performance, and related brain activity recorded
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Enrollment
28
tACS applied to the MFC at a frequency of 6 Hz, using a high-definition 1×4 electrode configuration with individualized current intensity, delivered for 20 minutes.
Except for turning down the current intensity to zero during the 20-minute period, all other parameters are identical to those in 6Hz-group.
Department of Rehabilitation Medicine, The First Affiliated Hospital, Sun Yat-sen University
Guangzhou, Guangdong, China
Verbal Fluency Test (VFT)
The VFT assesses abilities such as thought initiation, rapid word retrieval, and cognitive flexibility. It has two parts: 1.Phonemic Fluency Test (PFT), people needed to name as many Chinese words as possible beginning with "fa" or "xiao" within 60 seconds. 2.Semantic Fluency Test (SFT), people needed to name as many items as possible from categories such as "fruits," "vegetables," "animals," and "occupations" within 60 seconds. The number of correct and non-repeated words produced within the time limit were recorded.
Time frame: Assessments were completed at baseline, after two weeks of stimulation, and at 1- and 3-month follow-ups.
Digit Span Test (DST)
The DST assesses working memory and selective attention. People repeat a series of numbers in the same order (forward) or reverse order (backward) as spoken by the examiner. The maximum correctly repeated sequence length was recorded.
Time frame: Assessments were completed at baseline, after two weeks of stimulation, and at 1- and 3-month follow-ups.
Trail Making Test (TMT)
The TMT assesses complex visual scanning, conceptual tracking, cognitive flexibility and divided attention. It has two parts: TMT-A: People draw a trail by connecting 25 Arabic numbers in ascending order. TMT-B: the trail alternates between connecting 12 Arabic numbers and 12 Chinese characters. The time taken to complete each task is recorded.
Time frame: Assessments were completed at baseline, after two weeks of stimulation, and at 1- and 3-month follow-ups.
Speech motor integration ability as assessed by a well-established paradigm: frequency-altered feedback (FAF) task
In the FAF task, participants needed to sit in a sound-attenuated room and produce the vowel /u/ according to instructions. The acoustic signal is recorded and randomly shifted in pitch by an external device. The pitch-shifted voice is then fed back to the participant. This unexpected pitch perturbation elicits either an opposite or a following acoustic compensation response. The amplitude and timing of this response are recorded and used to assess the participant's speech-motor integration ability.
Time frame: Assessments were completed at baseline, after two weeks of stimulation, and at 1- and 3-month follow-ups.
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