PWP stands for people with Parkinson's. No more, no less. I wonder, however, how long it will stay in use. Its easier just to use the collective noun "Parkies," though suppose "PWP" is a bit more elegant. The trouble (for purists?) is that one has to put an "s" on the end for it to sound right: it wont do to say "all the PWP I know are...." even though saying "all the PWPs I know are..." is equivalent to saying "Peoples with Parkinson's...." The upper case P is OK , I guess, for both PWPs and Parkies so long as one is consistent in such usage.