is there no scope of improvement in the patient suffering from patkinson disease

My grandfather is 78yrs old. He has been diagnosed with parkinson disease around 20yrs ago. We have seen many changes in him in past few months such as he is not able to walk properly, often fall down or walk with the help of walker. He sleeps very late at night and wakes up next day afternoon. He at times beat my grand mother. He has lost his weight a lot and his body shakes considerably. Recently he had problem in identifying people around him. From long time, he had been bed wetting more than 5times at night. He is a paediatrician and so no matter how he is he always wants to go to clinic. Due to medicines effect his speech is not clear. He doesnt want to eat anything and stay long hours in washroom. My family is worried. Is there no end to such problems? What is the stage of the disease? Is it so worse or too late for us to do anything? Can't we do anything?