[Informed consent and mental competence of the elderly in medical-scientific studies].

The decision whether a potential subject is competent or incompetent is a necessary and crucial part of conducting medical research in the elderly. The assessment of competency is required by the legal and ethical frameworks in which this research has to take place. The state of play in the national and international discussions of bills for legislation of this topic will be summarized. Especially the practical consequences of this forthcoming legislation for researchers will be explained. The ethical framework for medical research with elderly subjects will be described from a historical point of view. By means of a review of relevant literature the legal definition of competency will be operationalized and tests for its assessment will be discussed. Competency of consent is assessed by asking several questions about the essential elements of the study. The introduction of a try out of the study for a subject before asking consent ('experienced consent') is propagated as a method to optimize this consent of elderly subjects. Special conditions for giving the required information to elderly subjects, for the informed consent by proxy and for the inclusion of nursing-home residents, are discussed.