Vestibular Stimulation in Parkinson's Disease

The purpose of this study is to determine whether caloric vestibular stimulation improves symptoms of Parkinson's Disease.

Parkinson's Disease (PD) is a nationwide public health problem, inflicting a complex constellation of physical and neuropsychiatric symptoms which are shown to progress with time. This research will investigate the potential of caloric vestibular stimulation (CVS), a non-invasive form of brain stimulation, as a treatment for individuals who suffer from Parkinson's Disease. Investigators will investigate whether core cognitive and physiological deficits are responsive to stimulation by comparing participants' performance on behavioral and physiological measures after baseline and either active or placebo stimulation phases with the aim of drawing initial insights into the application of CVS within this population. The study design is based on a single-case study that recently demonstrated durable, clinically meaningful gains in the motor and nonmotor symptoms of PD.

Participants will be receiving an active Caloric Vestibular Stimulation treatment for a duration of 8 weeks, 7 days a week, twice daily for 19 minutes.

Participants will be receiving a Sham Caloric Vestibular Stimulation treatment for a duration of 8 weeks in the same manner as the active arm: 7 days a week, twice daily for 19 minutes. Individuals allocated to this arm will be later crossed over, in unblinded fashion, to the active arm if the treatment shows evidence of efficacy and safety.

The NMSS is a 30-item rater-based scale to assess a wide range of non-motor symptoms in patients with Parkinson's disease (PD). The NMSS measures the severity and frequency of non-motor symptoms across nine dimensions. Score range of 0-360, with 0 being no symptom burden

Change From Baseline in the MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part II: Motor Aspects of Experiences of Daily Living

The MDS-UPDRS Part II is a 13-item patient-reported assessment of activities of motor aspects of experiences of daily living. Scores range between 0-52, with the higher score indicating greater impairment to activities of daily living

Change From Baseline in the MDS-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) Part III: Motor Examination

The MDS-UPDRS Part III is a 33-item assessment of motor function evaluated by a trained blinded rater. Scores range between 0-132 with higher scores indicating more severe motor symptoms

rapid screening instrument for mild cognitive dysfunction, with a score range from zero to 30, with higher being closer to normal

a brief measure that is commonly used to assess daytime sleepiness in PD and other disorders. Scores can range from 0 to 24. The higher the score, the higher that person's average daytime sleepiness

questionnaire for evaluating the impact of fatigue. scores range from 9-63 with a higher score for greater fatigue.

questionnaire for use in clinical and economic appraisal and population health. scores range from 0-100 for each question with 0 being the worst and 100 being the best

self-reported outcome measure assessing the impact of health on an individual's everyday life. Scores range from 0 to 100, with higher scores indicating better physical and mental health functioning

self-rating scale developed to assess psychological distress. scores range between 0-21 with higher scores equaling more severe impairment

Inclusion Criteria: Participants must be diagnosed with idiopathic Parkinson's Disease as defined by the UK PDS Brain Bank Criteria. Participants must report limitations to Activities of Daily Life (ADL, UPDRS subscale 2) Capacity to consent to the study Motivated to comply with the protocol An understanding of English sufficient to comply with the protocol Spouse/ carer willing to support the participant throughout the study Exclusion Criteria: Diagnosis of induced Parkinson's or essential/dystonic tremor Premorbid psychiatric history (including affective disorder, psychosis or deliberate self- harm) Previous exposure to neurostimulation Inner ear pathology

De-identified individual participant data for all clinical outcome measures have been made available.