Alzheimer's, Advance Directives, and Interpretive Authority.

Philosophers have debated whether the advance directives of Alzheimer's patients should be enforced, even if patients seem content in their demented state. The debate raises deep questions about the nature of human autonomy and personal identity. But it tends to proceed on the assumption that the advance directive's terms are clear, whereas in practice they are often vague or ambiguous, requiring the patient's healthcare proxy to make difficult judgment calls.