People and lawyers are trying to figure out if a person can choose to die if they get dementia or Alzheimer's and it is getting a little controversial.
Generally, you cannot direct your proxy or medical staff to end your life with drugs or by other methods if you develop Alzheimer's. However, people are now saying in their advance directives that they do not want to be fed or hydrated by third parties if they have dementia or Alzheimer's.
Essentially, this is choosing to die by voluntarily stopping eating and drinking.
The controversy is whether you can in fact do that. After all, can your proxy can order the facilities and medical team not to feed or hydrate you.
The question is being debated and litigated now. In New York and some other states, you can't because the law prevents the withdrawal of oral nutrition or hydration at all, no matter what a proxy or directive says. The New York Times has a great article on this topic.