Can inhaling hydrogen gas or drinking hydrogen rich water improve symptoms of Parkinson's?

The purpose of this thesis was to investigate the effects of Hydrogen (H2) on motor and non-motor symptoms in people with Parkinson's (PwP), and to investigate the potential mechanisms of H2 through measurements of markers of inflammation, neuroinflammation and antioxidant capacity.

H2 has some demonstrated neuroprotective effects in animal models of Parkinson's disease (PD), suggesting benefits for PwP but research has reported opposing findings. There is an imperative need to slow progression of PD as there is no known cure and there are exponential increases in diagnoses in part due to ageing and increased awareness of PD. Therapeutic interventions which may help reduce motor and non-motor symptoms of PD should be explored, and H2 has demonstrated that it is safe to consume, has no side effects and is well tolerated. However, optimal route of administration, dose, and timing of H2 has yet to be established, and as PD is an incredibly complex and heterogeneous disease, this may contribute to difficulty in establishing if H2 can improve health outcomes for PwP.

A pilot study (Study 1) in healthy participants first aimed to assess if the timings of measures and acceptability of an intervention were feasible for a future proposed study (Study 2) in people with Parkinson's (PwP) and helped refine clinical practices. Measures were the Flanker Compatibility Task to assess cognition, Purdue Pegboard Test to measure manual dexterity and the Profile of Mood State - Short Form to assess mood. This study demonstrated the intervention was well-tolerated with no adverse effects reported.

The protocol in Study 2 followed the same design as Study 1 and was the first known study to assess the effects of an acute H2 inhalation period in PwP. Measures were the same as Study 1, with the addition of the MDS-Unified Parkinson's Disease Rating Scale 3.15 to measure postural tremor and blood samples to measure total antioxidant capacity (TAC). This preliminary study showed H2 increased TAC.

Subsequently, a study with one participant which assessed a chronic inhalation period was then carried out. Measures were the same as Study 2 with the addition of the Movement Disorder Society - Non-Motor Rating Scale, Timed Up and Go Test and the six-minute walk test with tremor not being assessed. It was found that H2 had no reported side effects, reduced systolic blood pressure, increased walking distance, and increased TAC.

Study 4 measured H2 concentration of hydrogen rich water (HRW) and dissipation rate. This study demonstrated that if participants did not drink HRW immediately after production, then H2 concentration would still be maintained by 90 % after one hour, and approx. 80 % after four hours, which then led to the final study of the thesis.

The final study in this thesis explored drinking HRW in PwP and if this affected motor and non-symptoms and biomarkers of inflammation, neuroinflammation and oxidative stress (as well as TAC). This preliminary study demonstrated that H2 increased IL-6 and TAC but did not affect functional movement, or motor or non-motor symptoms of PD.

In summary, this thesis provides preliminary evidence that H2 increases total antioxidant capacity (TAC) in PwP, however, it does not affect motor and non-motor symptoms, which may prove beneficial over time for PwP in helping to mediate their symptoms.