Suggest Treatment For Parkensons

Thank you. My son in law is 56 yrs old and has been diagnosed with Parkensons for four years. His cognative abilities are slowing, tremmors and posture, shuffling excellerating. And his driving of a car is frightning. He gets lost in areas he driven for years, stops at a red light but doesn t wait for it to change. I;m afraid for my grandchildren to ride with him driving. My question is: how can we with the least trauma/drama get him to stop driving short of have his license revolked? Sorry, I was unaware of a charge. I m on a fixed income and cannot pay. But thanks for listening.