Consent and Capacity in Dementia Research: Rethinking Proxy Decision-Making

Abstract

Dementia research depends on enrolling people whose decision-making capacity is often partial, fluctuating, or absent, which places substantial strain on the standard model of individual informed consent. This review examines how the field has tried to make research participation ethically defensible despite this strain, beginning with the difficulty of assessing decision-specific capacity that changes over time and by task. It then surveys proxy or surrogate consent combined with ongoing assent and dissent monitoring, and the unresolved question of what standard a surrogate should apply when the research offers the participant no
direct benefit. We examine advance research directives as an alternative that lets a person specify research wishes while still competent, and the long-running philosophical dispute over whether such directives should bind a person whose values may have changed with disease progression. We conclude that no single mechanism resolves the tension between honoring a person's present will and their prior wishes, and that defensible practice likely requires combining risk-sensitive capacity assessment, genuine attention to assent and dissent throughout a study, and legal recognition for advance research directives that stops short of treating them as automatically dispositive.