  According to the threshold views, the earlier self has authority to determine the overall interests of the patient because the current self has lost crucial abilities that would allow it to ground these overall interests anew. This picture assumes that the earlier and current self are stages in the life of one entity, so that, despite the talk of local interests associated with each life-stage, there is an underlying continuity of interests between the two. But this is a very substantial assumption, and it has been contested by appeal to an influencial account of the metaphysics of  personal identity  over time, the psychological continuity account. Roughly, the idea is that, in the wake of a drastic transformation of one's psychology such as Alzheimer's disease, one does not survive as numerically the same individual, so whatever interests one's predecessor in one's body may have had are not a suitable basis for decisions on behalf of the new individual who has emerged after the transformation (Dresser 1986). The lack of identity between the earlier and current self undercuts the authority of the former over the latter.