Parkinson's disease commonly affects walking ability, balance, mobility, and cognitive function, increasing the risk of falls and reducing independence. Virtual reality (VR) has emerged as a promising rehabilitation tool, but the potential differences between immersive and non-immersive VR approaches remain unclear.

This pilot randomized comparative study aims to evaluate the feasibility, safety, and preliminary effects of immersive virtual reality (IVR) and non-immersive virtual reality (NIVR) rehabilitation in individuals with Parkinson's disease. Participants will be assigned to either an immersive VR intervention using a head-mounted display or a non-immersive VR intervention using a tablet-based exergaming platform.

Both interventions will be delivered over six weeks and will target gait, balance, mobility, motor-cognitive interaction, and functional performance. Outcomes will include gait parameters, functional mobility, freezing of gait, cognitive function, adherence, and safety.

The findings will help determine whether different VR modalities produce distinct motor and cognitive responses and will inform the design of future larger clinical trials.

Parkinson's disease is a progressive neurodegenerative disorder characterized by motor impairments such as gait dysfunction, postural instability, mobility limitations, and freezing of gait, as well as cognitive deficits affecting attention, executive function, and dual-task performance. These impairments contribute substantially to disability, fall risk, and reduced quality of life.

Virtual reality-based rehabilitation has emerged as a promising approach for delivering task-oriented, repetitive, and engaging interventions that simultaneously address motor and cognitive domains. However, immersive and non-immersive virtual reality systems differ substantially in their interaction characteristics, sensory feedback, and degree of user immersion, and their comparative effects in Parkinson's disease remain insufficiently understood.

The purpose of this pilot randomized comparative study is to evaluate the feasibility, safety, and preliminary clinical effects of immersive virtual reality (IVR) compared with non-immersive virtual reality (NIVR) rehabilitation in individuals with idiopathic Parkinson's disease.

Participants diagnosed with Parkinson's disease will be allocated to one of two intervention groups. The IVR group will receive rehabilitation using the KINESIX XR platform delivered through a head-mounted display with real-time motion tracking and three-dimensional interactive environments. The NIVR group will receive rehabilitation using the Active Arcade exergaming platform delivered on a tablet device. Both interventions will be supervised and delivered over a six-week period, consisting of ten treatment sessions in addition to baseline and post-intervention assessments.

Outcome measures will include spatiotemporal gait parameters, functional mobility, dual-task performance, turning ability, freezing of gait symptoms, cognitive function, adherence to treatment, and safety outcomes. Assessments will be conducted at baseline and immediately following completion of the intervention program.

The results of this study are expected to provide preliminary evidence regarding the differential motor and cognitive responses associated with immersive and non-immersive virtual reality rehabilitation and will support the development of future adequately powered clinical trials in Parkinson's disease rehabilitation.

Inclusion Criteria:

• Age between 45 and 75 years.
• Diagnosis of idiopathic Parkinson's disease.
• Hoehn and Yahr stage between 1.5 and 4.
• Ability to walk independently or with an assistive device (cane or walker).
• Low to moderate fall risk, defined as a Timed Up and Go (TUG) score <20 seconds.
• Ability to provide written informed consent.

Exclusion Criteria:

• Diagnosis of other neurological or movement disorders.
• Severe cognitive impairment, defined as a Montreal Cognitive Assessment (MoCA) score <18.
• Severe visual impairment not correctable with lenses.
• History of epilepsy.
• Uncontrolled psychiatric disorders.
• Previous deep brain stimulation.

De-identified individual participant data underlying the results reported in this study will be available upon reasonable request to the corresponding author.

Data will be available beginning 6 months after publication of the primary study results and will remain available for 5 years thereafter.

The data that support the findings of this study are not publicly available because they contain information that could compromise participant privacy. De-identified individual participant data may be made available to qualified researchers upon reasonable request to the corresponding author for purposes of scientific research, subject to review and approval of the proposed use and execution of an appropriate data-sharing agreement.

Outcome assessments were performed by an evaluator who was blinded to group allocation. Participants and treating therapists were aware of the intervention received due to the nature of the virtual reality interventions, but the assessor responsible for baseline and post-intervention evaluations was not informed of treatment assignment.