Dementia, Advance Directives, and Discontinuity of Personality.

We argue that an advance directive (AD) is not invalidated by personality changes in dementia, as is claimed by Rebecca Dresser. The claim is that a new person results under such personality changes, and that the former person cannot write an AD for the new person. After stating the argument against ADs in cases of dementia, we provide a detailed examination of empirical studies of personality changes in dementia. This evidence, though not strong due mainly to low sample sizes and different notions of personal identity, does not support Dresser's position. Given the weakness in the empirical evidence, we turn to a philosophical defense of ADs based on a social contract view supporting the current interests of those writing ADs. Additionally, we argue that personality change is not equivalent to change in personal identity, as would be required by the argument against ADs in cases of dementia.