our poor levodopa deprived brains need it.
I started back on it to help my frozen shoulder syndrome and after a couple of days I can report improvement.
I would ask his MDS about a trial of sinemet. I would also take him hiking as he no longer has the incentive to do it on his own. He could be avoiding it because he is nervous about going alone.
Be aware that it takes about 3 weeks before anti-depressants to make a noticeable difference/ Also not all work on PD'ers, so you may need to try sevral different ones to find one that works. it takes a while to find a efficacious med protocol for him, but don't give up!!!
hope this helps

Charlie