The ethics of informed consent in Alzheimer disease research.

Clinical research on Alzheimer disease (AD) is much needed but requires the participation of patients with substantial cognitive impairment who have difficulty providing informed consent. Despite decades of debate, policies regulating such research are not well-defined. Although numerous studies have underscored the difficulties of obtaining informed consent for clinical research from patients compromised by AD, there is also increasing evidence that such individuals and their surrogates can make decisions about research participation that are consistent with the patients' values. Policy discussions and future research should consider how the ethical reservations about enrolling incapacitated patients in research could be mitigated by developing ways to promote the congruence between surrogates' decisions and patients' values.