In this paper, I consider objections to advance directives based on the claim that there is a discontinuity of interests, and of personal identity, between the time a person executes an advance directive and the time when the patient has become severely demented. Focusing narrowly on refusals of life-sustaining treatment for severely demented patients, I argue that acceptance of the psychological view of personal identity does not entail that treatment refusals should be overriden. Although severely demented patients are morally considerable beings, and must be kept comfortable whilst alive, they no longer have an interest in receiving life-sustaining treatment.