Consent and refusal in dementia research: conceptual and practical considerations.

This article discusses types of consent refusals, rates of refusal, factors that affect consent, and methods to increase rates of consent in elderly research participants and in those with dementia in particular. Refusals can be categorized according to several types: complete refusal, refusal that is time-contingent, partial refusal, and contingent agreement. Rates of consent vary greatly across studies of persons with dementia. This variation can also be affected by different methodologies of calculating rates, in addition to differences in content of studies, populations, and procedures. To warrant consent, a study must first be scientifically sound, with a high likelihood of advancing knowledge, and must provide maximal protection to participants. Consent rates are affected by the following factors: levels of anticipated risks and benefits of the study, relationships among the different caregivers involved in the care of the potential subject, the ability of the researcher to properly identify and locate the person who needs to provide consent, characteristics and attitudes of the person providing consent, and the method of obtaining consent, including timing, location, method of presentation, and type of consent requested. An understanding of these issues can assist the researcher in tailoring research procedures so as to maximize rates of consent. It also raises ethical issues that warrant further discussion concerning the process of obtaining consent from and for persons with dementia.