Thx for the interesting article. Another semi-separate but complementary "axis" is the Endocannabinoid system which is comprised of CBD (cannabinpod ) receptors in the brain and nervous system. In a nutshell, by way of example, the symptoms of Parkinson's can be lessened by smoking MJ or taking the non-psyocative ingredient CBD (legal and available without a Rx).
https://scienceofparkinsons.com/tag/cannabidiol/ https://scienceofparkinsons.com/tag/cannabidiol/