Ethical research with the developmentally disabled.

The developmentally disabled constitute a vulnerable population in the context of nontherapeutic experimentation. Their vulnerability is characterized by diminished decision-making capacity and by susceptibility to coercive situations that may bring voluntariness into question. The international consensus is that research involving this population should be permitted, but only if the consent of a legal guardian is obtained and appropriate safeguards are introduced. Therefore, legislation regulating the ethical conduct of research should be enacted, including provision for substituted consent in the research context. Although researchers seeking the participation of a developmentally disabled individual in a protocol must presume the person to be capable of participating in the decision, they must conduct competency assessments if the person's ability to make such a decision is in doubt. Information must be presented in such a way as to maximize the individual's contribution, and capacity must be reevaluated on an ongoing basis. In addition, research on the developmentally disabled presents specific challenges to establish competency, the selection of subjects, the characteristics of the decision maker, and the model to be used in making substituted decisions.