To explore the safety, feasibility and net symptomatic effects of multiple (3x/week, for 4 weeks) intermittent hypoxia treatment sessions in individuals with PD. Secondary outcomes include exploring induction of relevant neuroprotective pathways as measured in serum.

Intermittent hypoxia therapy is a non-pharmacological intervention used by athletes and individuals with cardiovascular disease, amongst others. The safety and feasibility of (intermittent) hypoxia therapy and its short-term effects on Parkinson's disease (PD) symptoms were assessed in a previous exploratory phase I trial. However, the net effects of multiple hypoxia treatment sessions on PD symptoms are unknown. The results of the previous phase I trial informed the study design of the newly proposed phase 1b-2a safety and efficacy trial.

45 minutes of normobaric intermittent hypoxia (FiO2 0.16 for 5 minutes interspersed with 5 minutes normoxia) will be delivered via a hypoxicator (a device that titrates decreased fractional oxygen from room air) through an oxygen mask in the hospital and subsequently at participants' homes. Interventions will be conducted 3 times a week, for 4 weeks in total.

Inclusion criteria

• Informed consent
• Clinical diagnosis of Parkinson's disease by a movement disorder specialized neurologist.
• Hoehn and Yahr staging 1 to and including 3 (indicating mild to moderate PD).

Exclusion criteria

A potential subject who meets any of the following criteria will be excluded from participation in this study:

• Individuals with diseases leading to restrictive and obstructive pulmonary diseases, sleep apnea and cardiac output deficits, such as pulmonary fibrosis, COPD, sleep apnea or excessive alcoholic intake, and congestive heart failure respectively
• Individuals with coronary artery disease NYHA classes III and IV
• Arterial blood gas abnormalities at screening procedure
• Individuals with shortness of breath or other airway or breathing-related inconvenience related to lack of dopaminergic medication
• Inability for in-clinic measurements in OFF phase
• Individuals with active deep brain stimulation

Anonymized data will be shared with The Michael J. Fox Foundation for Parkinson's Research (the study funder). This data may be kept for storage at a central repository either hosted by The Michael J. Fox Foundation, its collaborators, or consultants and will be kept indefinitely. Anonymized data will be made publicly available for the intended use of research in Parkinson's disease as well as other biomedical research studies that may not be related to Parkinson's disease.

1.5 years

Identical mode of administration and identical machinery used to deliver the intervention, only inside of machine is different (same ventilator, no active element in the placebo machine)