I don't have a lot of experience with Alzheimer's, but in the couple of cases I've observed, though not from very close, the patient didn't seem to be suffering

I don't have a lot of experience with Alzheimer's, but in the couple of cases I've observed, though not from very close, the patient didn't seem to be suffering or unhappy at the end. There was a brief intermediate period of paranoia, in which they obviously were unhappy, but then they settled down into a state of complete doolallitude in which they were an expensive burden for professional carers but seemed quite cheerful. That makes the euthanasia question a bit harder.