Terry Pratchett: Choosing to Die (2011)

In 2008, celebrated author Sir Terry Pratchett was diagnosed with Alzheimer's disease. Nearly three years on, Pratchett considers ways to end his life before the disease consumes him. His search takes him to Switzerland, where he meets some of the staff and clients of a non-profit organisation that provides assisted suicide to people suffering from severe ailments and terminal illnesses. In a quiet cottage outside Zurich, we—along with Sir Terry—witness a man's final moments with his wife.

Source: TMDb