It seems like your client needs medications to control his cholesterol, restless leg syndrome, Parkinson’s, and depression problems. I guess you must have already got a medical clearance and hopefully talked to his doctor for any suggestions/recommendations. He seems like a difficult case, but maybe you could try to add some more cardio in his training before doing anything more strenuous with strength and/or higher intensity. I don’t know what else I can add to this since I don’t know anything about this person. Maybe someone else here with more experience with cases like yours could be more helpful.