The capacity to appoint a proxy and the possibility of concurrent proxy directives.

With the projected increase in the number of persons with dementia (who eventually lose their capacity to give informed consent to treatment and research), third-party decision-making will become even more common than it is today. We argue that, because there are situations in which an appointed proxy is preferred over a de facto surrogate, it is ethically important to understand the capacity of persons with dementia to delegate their decision-making authority regarding treatment and research decisions. In this paper, focusing mainly on the research consent context, we examine the idea that persons suffering from neurodegenerative disorders may retain significant abilities-including sufficient capacity for delegating one's authority for giving consent to research-even if they are not capable of giving independent consent themselves. We first propose a rationale for assessing the capacity to appoint a proxy and then describe a novel interview instrument for assessing the capacity to appoint a proxy for research consent. Copyright (c) 2006 John Wiley & Sons, Ltd.