What most people call Cat's claw is a South American vine, Uncaria tomentosa, commonly available in health food stores. The TOA-free variety is used successfully in Lyme Disease which, some say, is implicated in PD.
Gou Teng, Uncaria rhynchophylla, is a different plant, rarely used in the west. It is used in Traditional Chinese Medicine (TCM) but is hardly ever used alone. My girlfriend is a TCM doctor who makes a formula that contains Gou Teng among many other things, e.g. Wu Gong
http://www.youtube.com/watch?v=kQPeQ...eature=related (centipede.)
I take this formula to halt the progression of the disease though it does lessen tremors quite a bit for me. She emphasizes consulting a TCM doctor before experimenting with exotic TCM ingredients. If you want to white rat yourself you can get Gou Teng at
http://www.emersonecologics.com