My dad has had Parkinson's for many years. In the last 1-2 years, it's left him unable to walk. Now in the last 3-6 months, his voice is nearly gone. Very difficult to understand anything he says. He is 86 but still incredibly sharp. Are there any treatments in clinical phases or anything to do besides the typical day to day doctor treatment and meds? If this is how it ends, are there any better ways to communicate?