When an adult suffers from a disorder that impairs his or her capacity to consent, may another person enroll that individual in research? The answer, it appears, is not a simple "yes" or "no," but rather "it depends."

The lack of clear legal answers to this question has significant ramifications for the conduct of important research on disorders that affect many individuals. A growing population in our country suffers from illnesses that may affect decision-making, such as dementia, mental retardation, or, in certain instances, severe neuropsychiatric disorders. To illustrate this point, consider Alzheimer's disease ("AD"). As the most common cause of dementia, the current and projected impact of AD is immense. An estimated four to fifteen million people are expected to suffer from Alzheimer's disease by the year 2047. Beyond the quantitative impact of AD, the personal and relational costs of the disease are staggering. Patients in later stages may not recognize family members and often lose many of their core human traits and abilities. Many patients face institutionalization because of the common, yet extremely challenging, behavioral and psychiatric expressions of the disease. The financial costs are also significant. Current annual costs, both direct and indirect, approach $100 billion in the United States alone. It is urgent that research on this disease be strongly encouraged and facilitated.