[aljungberg]

That's awesome. It's not easy to get seniors to spend that much time in the gym, so well done if you contributed to motivate her! Physical exercise is indeed one of the few Parkinson's treatments that there's little doubt about.

In terms of reversing the damage, look into photobiomodulation (PBM) aka red light therapy. In "Improvements in clinical signs of Parkinson's disease", Liebert et al in 2021, she shows improvement in all symptoms including cognition, which is one of preciously few such results I've found in my extensive search of the literature[1]. Caveats are that this was a proof-of-concept study with n=6 only and that the red light helmet is somewhat expensive if you want to try it. There's a Canadian company that makes one for above $2000 (modern, very sci-fi thing), and a more hackerish version from an Australian company for ~$700 (pairs of diodes on aluminum bands you have to finish assembling yourself).

[1]: At least which are actionable for the public. There are tons of trials but good luck getting in early unless you can donate a new library to the university! Gene therapy, stem cell therapy, GDNF, drugs that target alpha-synuclein are all promising but not yet accessible. PBM is something you can do today and since mitochondrial dysfunction is a leading hypothesis in the pathogenesis of PD, the treatment fits.