What hypoxia does is lower brain oxygen. So why is this important in Parkinson's? Oxygen is a coezyme for an enzyme called MAOB, which gets rid of dopamine and produces H2O2 (Hydrogen Peroxiode). It is well know thatpeople with Parkinson's have polymorphisms in MAOB that put them at risk.

https://pmc.ncbi.nlm.nih.gov/articles/PMC6074924/

Their enzyme activity is high, and gets higher as they age. So getting rid of oxygen (hypoxia) slows down the MAOB enzyme, reducing H2O2 production, and slowing Parkinson's. Hypoxia also reduces DNA methylation (HYPOmethylation) which is even more important (more later).

https://pmc.ncbi.nlm.nih.gov/articles/PMC7016890/

Hydrogen Peroxide is the real enemy in Parkinson's since it is responsible for the destruction of the Dopamine neurons.

https://pubmed.ncbi.nlm.nih.gov/7675214/

How does Levodopa fit in with all of this? Levodopa makes Dopamine via an enzyme called DDC. DDC uses vitamin B6 as a cofactor. Giving people Levodopa lowers B6

https://pubmed.ncbi.nlm.nih.gov/35569990/

which increases homocysteine and DNA methylation (HYPERmethylation. HYPOmethylation of DNA is linked to Parkinson's.

https://pmc.ncbi.nlm.nih.gov/articles/PMC6557551/

And they know that Hypomethylation of the alpha-synuclein (SNCA) gene is the cause of Parkinson's.

Increase DNA Methylation and you decrease Parkinson's. One way to do that is to get more zinc becasue it increases DNMT gene activity (methylation) and low zinc is linked to Parkinson's.

https://www.nature.com/articles/s41598-017-04252-0

Just a note I could not fit in the title, this is in mice, but very relevant.