Parkinson's disease (PD) is commonly associated with impaired motor learning and reduced motivation, both of which can negatively influence rehabilitation outcomes. Prior cross-sectional evidence suggests that providing individuals with PD self-controlled access to training parameters enhances motor learning, increases motivation, and facilitates cognitive processing. However, the effects of self-controlled practice implemented across repeated training sessions remain underexplored. Moreover, given that dysfunction of fronto-striatal circuits in PD may limit the neuroplastic response to motor training alone, adjunctive neuromodulatory priming approaches such as repetitive transcranial magnetic stimulation (rTMS) may be required to optimize therapeutic efficacy. To date, it remains unclear whether rTMS priming combined with self-controlled motor training yields superior clinical benefits, and whether stimulation of different cortical targets produces differential effects. In particular, the dorsolateral prefrontal cortex (DLPFC), a key region involved in cognitive control and motivation, may offer distinct therapeutic effects compared with stimulation of the primary motor cortex (M1). This study aims to investigate the effects of rTMS priming over the DLPFC or M1, followed by self-controlled motor training, in individuals with PD, and to compare these effects with a sham stimulation condition.
This single-blinded, randomized control trial will recruit 90 individuals with PD, who will be matched into 45 pairs and randomly assigned to one of three stimulation conditions: DLPFC, M1, or sham. Within each pair, one participant will be allocated to a self-controlled practice condition, and the other to a yoked (paired-control) condition that receives identical training content determined by their matched counterpart. Each participant will undergo 12 intervention sessions. In each session, rTMS will be applied first as a priming intervention, followed immediately by 45 minutes of standardized physical therapy-based motor training. For the DLPFC group, stimulation will target the left DLPFC; for the M1 group, stimulation will be applied over the M1 contralateral to the more affected limb; and for the sham condition, the coil will be rotated 90 degrees to mimic stimulation without effective cortical activation. During the training phase, participants in the self-controlled condition will be allowed to select aspects of their practice content, whereas yoked participants will follow the corresponding selections made by their matched partner.
The primary outcome measure is the Unified Parkinson's Disease Rating Scale (UPDRS). Secondary outcomes include assessments of cognitive function, apathy, non-motor symptoms, gait performance, balance, functional mobility, falls efficacy, and quality of life. Neurophysiological outcomes will be assessed using single- and paired-pulse TMS to evaluate corticospinal excitability and cortico-cortical connectivity, particularly between DLPFC and M1 networks. All assessments will be conducted in the medication-on state by blinded evaluators at baseline, immediately post-intervention, and at one-month follow-up. Data will be analyzed using mixed-effects repeated-measures ANOVA to examine group-by-time interactions and intervention effects. This study seeks to determine whether rTMS priming over cognitive-control versus motor networks differentially enhances the efficacy of self-controlled motor training, and whether such combined interventions can induce sustained improvements in motor and non-motor outcomes in PD.
diagnosed of PD by neurologists and age above 18 years old
able to follow the researcher's instruction (the Montreal Cognitive Assessment ≥ 24)
able to stand and walk independently for 10 minutes with or without assistive devices
have neurological disorders other than PD (e.g., Parkinson plus syndrome, cognitive impairment, dementia, stroke)
have contraindications to receive TMS, such as a pacemaker or deep brain stimulator implanted in the body
a self-history of seizure or a family history of epilepsy
pregnancy
Factorial
Repetitive Transcranial Magnetic Stimulation (rTMS)
DeviceThe iTBS paradigm will be used to prime the neuronal excitability of the DLPFC or M1 based on the group allocation. The patterns of iTBS are triplets of stimuli at 50Hz frequency repeated in 5Hz bursts with a 2 second train repeated every 10 seconds for a total of 190 seconds, which will result in 600 stimulation pulses. The intensity will be set at 80%-120% of motor threshold of the tibialis anterior (TA) or first dorsal interosseous (FDI) muscle of the more affected limb. As for the sham rTMS groups, the coil will be placed over the M1 hotspot but turned 90 degrees away so that the surface of the coil will be 90 degrees perpendicular to the scalp.
Physical therapy
BehavioralAfter the iTBS priming procedure, the participants will receive 45 minutes of one-on-one physical therapy training targeting whole body and lower extremity function. Each training session will involve flexibility exercise, gait training, balance training, resistance exercise, or cognitive-motor dual task training.
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Treatment groupsSee each treatment group below.
Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS)
The MDS-UPDRS is currently the gold-standard scale used in the clinics as well as research to determine the disease severity of PD. The MDS-UPDRS contains four parts: (1) non-motor aspects of experiences of daily living, (2) motor aspects of experiences of daily living, (3) motor examination, and (4) motor complications. Each item is scored from 0 (no symptom) to 4 (most severe symptom), and the total score range for the MDS-UPDRS is from 0 to 260 with a higher score indicates greater disease severity.
Montreal cognitive assessment (MoCA)
The MoCA will be used to assess general cognitive function of the participants. It examines various cognitive functions, including set-shifting, visuospatial processing, abstract thinking, short-term memory, attention, verbal fluency, calculation, orientation, and digit span abilities. The total score of MoCA is 30 with a higher score suggests better cognitive function, and a score below 26 would suggest an increased risk of cognitive decline.
Short-form Lille apathy rating scale (LARS)
The LARS scale has 12 items categorized into 7 domains: everyday productivity, interests, take the initiative, novelty seeking, motivation-voluntary actions, emotional responses, and social life. Each item is scored on a 5-point Likert scale or a binary yes/no scale. The score ranges from -15 to 15 with a higher score suggests more apathetic symptoms. It has been established that a short-form LARS score ≥ -7 points is the cut-off score for identifying apathy in PD.
Non-motor symptoms scale for Parkinson's disease (NMSS)
The NMSS is a specifically designed 30-item scale to assess various non-motor symptoms of PD. It evaluates severity (score 0-3) and frequency (score 1-4) across nine non-motor domains: cardiovascular including falls, sleep/fatigue, mood /cognition, perceptual problems/hallucinations, attention/ memory, gastrointestinal tract, urinary, sexual function, and miscellaneous.
Gait performances
To measure walking ability, the participants will be asked to walk along a 10-meter hallway with their comfortable walking speed and fastest walking speed in single- and dual-task conditions. The Physilog®5 system (Gait Up, Renens, Switzerland) including two inertial sensors with built-in 3D accelerometers and gyroscopes will be fixated to the shoelaces area of both feet to record the walking data. The data will be sampled at a rate of 128Hz and will then be analysed by the Gait Up© gait analysis package (Gait Up SA, Switzerland). Gait parameters of interest include velocity, step length, cadence, foot-strike angle, and foot clearance.
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