Research involving persons with impaired decision-making capacity, such as persons with Alzheimer’s disease, remains ethically challenging, especially when the research involves significant risk. If subjects incapable of consenting to research studies were still able to appoint a research proxy, it would allow for an appointed surrogate, rather than a de facto surrogate, to represent the subject.
To assess the extent to which persons with Alzheimer’s disease retain their capacity to appoint a research proxy.
Design, Setting, and Participants
188 persons with Alzheimer’s disease were interviewed for their capacity to appoint a proxy (CAP) for research and to provide consent to two hypothetical research scenarios, a lower risk randomized clinical trial testing a new drug (drug RCT) and a higher risk randomized clinical trial testing neurosurgical cell implants using a sham control condition (neurosurgical RCT). Categorical capacity status for each subject was determined by independent videotape reviews of capacity interviews by five experienced psychiatrists.
Main Outcome Measures
Categorical capacity determinations for the capacity to appoint a research proxy, capacity to consent to a drug RCT, and capacity to consent to a neurosurgical RCT.
37.7% (40/106) of those deemed incapable of consenting to the drug RCT and 54.4% (86/157) of those deemed incapable of consenting to the neurosurgical RCT were still found capable of appointing a research proxy. Very few subjects (7/186, 3.8%) were deemed capable of consenting to the neurosurgical RCT by all five psychiatrists.
A substantial proportion of AD subjects thought incapable of consenting to lower or to higher risk studies have preserved capacity for appointing a research proxy. Since so few subjects are found to be unequivocally capable of providing independent consent to higher risk AD research, providing for an appointed surrogate even after the onset of AD, which might best be done in the very early stages of the illness, may help address key ethical challenges to AD research.