Barb; One doctor told me that when someone has a stroke, the cells are dead and new ones have to be trained to take on the same tasks but that in a disease like PD, it is the neurotransmitters that are affected and if we can increase the right ones, we can hope to restore movement or mental activities. This makes sense for Ken because sinemet increases dopamine and makes him able to move. He also takes zoloft which affects seratonin and makes him less depressed(he at one time had a deep clinical depression), and he takes Aricept which affects acetylcholine and makes his mind work better. This doctor was not a neurologist, but it does seem that if we can get the right neurotransmitter balance for Ken he does much better. Barbara Smith,CG/Ken/70/17