i wouldn't get that upset. economically, drug companies will have to attract every pd patient they can get if the treatment gets fda approval. a researcher obviously doesn't realize that early stage pd'ers will be very reluctant to risk brain surgery when they can do ok on drugs. neurologix took over a year to find 44 candidates for their gene therapy trial and it was certainly less dangerous operation than a dbs. my point is it's very difficult to find candidates for any pd trial.
the bigger issue is how do you show a statistical significant improvement in early stage pd'ers? how do they define "early stage"? honestly, i imagine they would take any healthy individual, they certainly want people that are going to live at least 5 more years, don't have other serious medical conditions and are healthy enough to undergo surgery.
that said, make sure you have an extra birth certificate.