Competency and consent in dementia.

Health care for demented older persons presents a range of ethical dilemmas. The disease process affects cognitive abilities, making competency a central issue. The syndrome of dementia carries a complex social overlay that colors perceptions of these patients and of their capacity for making decisions. An argument is made for a coherent, ethically based decision-making process that can be applied across the whole spectrum of dementia severity. The major ethical principles implicated in assessing a patient's ability to consent to treatment are reviewed. A sliding scale model of capacity is presented, in which the patient's ability to decide is weighed against the risk associated with the treatment decision in question. This model preserves the autonomy of the demented patient while minimizing the potential for harm. In situations where the patient is deemed incapable, two approaches that can be applied to making treatment decisions are contrasted. The 'prior competent choice' standard stresses the values that the patient held while competent. The 'best interests' standard moves the focus to the patient's subjective experience at the time the treatment is considered. The relative merits of these two concepts are evaluated in the context of dementia. Surveys of actual decision-making practice are contrasted with ethical and legal principles. The challenges inherent to applying the best interests standard are discussed. Despite the pitfalls, this standard offers an opportunity to restore the demented patient's sense of self.