Welcome to tke Internet and the Parkinson group. I am a little older than your dad but unfortunately I was diagnosed with PD about eight years ago when I was a lad of only about 65. In fact I have my symptoms are very similar to those of your dad in that have never had any tremor. My major symtom at first was the loss of foot speed in playing tennis. But I cotinued to play for a couple of years until I began falling when going back for overhead shots. I continued playing golf until this last season when I had to admit that It was no longer any fun. As regards your question re: Sinemet, from everthing I have learned , is the drug of choice of most of the Neurologists that I have run into over the years. The key factor is the dossage being prescribed and what agonist is prescribed to assist in the the functioning of the Sinemet. My doctor Fink who is at the Massachusetts General PD Center for movement control disorders in 1993 was prescribing a drug called Eldepreyl and an Agonist called Parlodel at that time I believe I was taking 25/100 Sinemet consisting of 2 tablets three times a day at approximately at 8am ,noon and 4 pm. With each of the Sinemet doses I was taking 1 Parlodel tablet of 5mg. My recollection was that the these worked quite well for my case. In 1996 my doctor began to prescribe a new Agonist Permax which he introduced by gradually increasing the amount of the Permax while decreasing the amount of Parlodel.