The aging process presents some unique challenges to respect for autonomy among older adults, particularly in relation to obtaining informed consent; and in the research environment those challenges are even more exquisitely complex. We will consider three possibilities that correspond roughly to the variations in decision-making capacities of older adults. The first two possibilities address recognizing and supporting the capacity of older adults to consent to research. The third addresses the possible and actual loss of that capacity.
Many older adults are as capable of informed consent for research as are other members of the population whose capacity to consent is not in question. The ethics of their participation as research subjects should not be presumed to be different from that of other adults. Some groups have been classified as vulnerable. Children, the devel-opmentally disabled, the mentally ill, and prisoners and other institutionalized groups have all been at various times considered vulnerable groups, due to their inability to exercise fully independent and informed judgment, their lack of information or comprehension, their inability to decide, or some coercive influence. Identifying a group as vulnerable has important ethical implications for research: membership in the group confers protections that may limit or even prevent one from consenting to participate. Being identified with that group, rather than one's individual capacities, becomes the criterion for whether one is allowed to choose to participate or not to participate. Robert Butler, the first director of the National Institute on Aging, coined the term ''ageism'' to describe the process of systematic stereotyping and discrimination against people because they are old (Butler, 1969). In practice, it is most ethical to assume that older adults are as competent as others to make their own choices. If there is doubt in an individual case or the subject population for a specific study, the protocol should include ways of confirming the capacity to make a decision.
Some older adults, due to conditions commonly associated with aging, are capable of informed consent, but require additional accommodation to exercise it. Older adults typically undergo changes that may affect the informed consent process. Changes in vision and hearing are among them. More than 37% of noninstitutionalized persons 65 and over report trouble hearing and 17.5% report trouble seeing (National Center for Health Statistics, 2002). Visual acuity, color discrimination, and sensitivity all tend to decrease with age (Fozard et al., 2001).
Cognitive changes include increased difficulty with selective and sustained attention (Rogers et al., 2001) and slowing of information processing and retrieval (Madden, 2001). In making decisions, older adults typically use less information and have more difficulty accurately using comparative information (Park, 1999; Hibbard et al., 2001).
These changes are sufficiently prevalent among the aging that they should be routinely considered in informed consent by older adults. The changes are typically moderate and their onset gradual, so that persons adapt (through eyeglasses and hearing aids, avoiding noisy restaurants, taking additional time for decision-making, etc.) and continue to lead autonomous lives. Accommodating these needs in the informed consent process is ethically important to ensure that older adults receive and comprehend the information they would use to make a considered and free judgment about participation. Such needs are not an indication that they should be protected by bypassing their own free choice.
Informed consent documents and recruiting materials should be high in visual contrast, with a simple large font. Discussions concerning participation should be held in an environment with a high light level, and minimal ambient noise and without visual and auditory distractions
(Metlife, 1999). Completing the consent process in several stages on separate occasions can help some older adults to have sufficient time to comprehend the study and perhaps to consult with a trusted friend (Tymchuk et al., 1990). These may be merely amenities or courtesies for younger subjects. With older adults they become ethically important as routine means of enabling them to exercise freely their autonomy.
Some older adults may not be able to provide informed consent. Various neurological, vascular, or psychiatric disorders, depression, or stroke can all affect an older person's capacity to consent. In the course of research a subject's lack of capacity may become evident. Concerns may develop during an initial interview or consent process, or in a run-in sometimes used prior to randomization (Ouslander et al., 1993). Or they could arise in the course of neuropsychological testing integral to the protocol. In any case, study procedures for addressing such findings or concerns should be addressed explicitly, from the time of initial submission to an IRB for approval (Kapp, 1998). General guidelines are available for assessing the capacity of impaired individuals (National Bioethics Advisory Commission, 1998). Although tests are available to measure specific capacities, there is no consensus on which of these tests should be used for determining capacity to consent to research (Curry, 2002).
Testing for cognitive impairment in the research context may create additional ethical issues. The investigator may receive evidence of a previously undiagnosed condition in a potential research subject. Keeping that information confidential might prevent the subject from accessing needed therapeutic assistance. Disclosing it might violate an expectation of confidentiality. To manage such issues, some studies retain an appropriate health professional or ask subjects to consent to disclosure of relevant study information to an identified primary care physician.
Should those who have lost the capacity to consent be barred from being research subjects? While this might be consistent with an ethical principle that all research participation should be voluntary, it could work against the best interests of those same persons. Individually, it could prevent access to promising new therapies available only in clinical trials. On a broader level, it could stifle progress in the very diseases or conditions that render persons cognitively incapable of consenting. Nevertheless, it should always be determined whether a study must include subjects who have lost the capacity to consent. If the study could proceed as well without them, then it is best to use only subjects able to consent.
Federal regulations effectively defer to state law by insisting that consent in such cases involve the subject's legally authorized representative. States have laws to address decision-making for incapacitated persons, but those laws are for the most part designed to address the need for health care decision-making in urgent situations.
The fit of those rules to research consent is at best inexact, and at times irrelevant to the research environment (Hoffman et al., 1998). As a result, there is active ethics discussion about how to act in the absence of laws and about what laws should be enacted. We will look specifically at two common features in state laws, proxy consent and advance directives, and discuss their application to the research environment.
In health care a proxy or surrogate makes decisions for the person who is incapable of consenting to treatment. While the specific method varies from state to state, there are generally two different ways. The person can, in advance of becoming incapable, name a proxy by granting power-of-attorney. In the absence of such a designation, the next of kin in an ordered list defined by state law becomes the decision-maker. The ethical expectation behind proxy consent is that the surrogate will have known the patient well enough and be sufficiently empathetic to the patient to make the decision the patient would have made. If what the patient would have decided is unknowable, the proxy must then make the decision that is in the best interests of the subject. Proxies in decision-making for nontherapeutic research are more problematic, because there is no expected benefit to the person beyond the altruistic satisfaction of contributing to the welfare of other humans in the future (Hoffman et al., 1998; Kapp, 1994). In such situations proxy consent for research could result in abusively using demented persons to the benefit of others. For that reason, the American Geriatrics Society holds that proxy consent should not be used where the subject is incapacitated, is unlikely to directly benefit, and will undergo more than minimal risk (American Geriatrics Society, 1998). The Alzheimer's Association has taken a similar position (Alzheimer's Association, 1997).
Both of those organizations consider an advance directive for research as a tool that is useful in ways that a proxy consent is not. The health care advance directive, frequently embodied in a living will, is intended to direct end-of-life care. Just as in health care, an advance directive for research does not involve substituting one person's judgment for another's; it is a documented decision by a competent person which is to be honored if and when that person becomes incapacitated (Dresser, 2001). Advance directives differ from proxy consent in that they rely directly on a person's own previously expressed and documented choice. A common criticism of advance directives in health care is that persons are seldom able to envision the specific end-of-life circumstances in which others will be expected to apply the directive (Fagerlin et al., 2004). It is at least as difficult to envision the kinds of research one might be a candidate for at some indefinite future date and how one's own needs and preferences might have changed by that time. For that reason, it is best not to assume an advance directive for research to be informed consent already given. It can serve as supportive documentation to guide a surrogate decision-maker (Sachs, 1994). Advance directives may also be helpful when a person is in the early stages of a progressive dementing illness, but still able to consent to participate in longitudinal research. Such an advance directive may guide the proxy when the subject is in later stages of the disease and no longer able to consent to continuing in or withdrawing from the study.
How great a risk may a surrogate consent to on behalf of an incapacitated research subject? What I shall call the ''conservative approach'' holds that non-therapeutic research that creates any risk of harm greater than minimal (i.e., greater than the risk of harm experienced in everyday living) should never be conducted on an incapacitated subject, even with proxy consent or an advance directive (Keyserlingk et al., 1995). Positions more favorable to proxy consent for research have begun to emerge. The Alzheimer's Association has taken the position that, in research involving more than minimal risk, subjects who stand to benefit individually and have a proxy's consent should be allowed to participate. Scientific progress in understanding and fighting diseases that rob older adults of their ability to remain autonomous may require research on persons who are unable to consent to or benefit from that research.
Although respect for autonomy is ethically good, human beneficence (contributing to the common good) is also good; and respect for individual autonomy should not always take priority over beneficence. The American Geriatrics Society proposes developing a mechanism for future consideration of subjects who cannot consent and who have neither an advance directive nor reasonable expectation of benefit, but only in studies especially promising in the benefit they eventually provide to society. Similarly, Stephen Post has advocated recently that, recognizing that defeating Alzheimer disease (the most prevalent older adult dementia) is a high priority for our common good, we should think differently about risk in this category of research (Post, 2003). The issue should not be whether a study poses only ''minimal risk,'' but where to set the upper threshold of allowable risk (''maximal potential risk''); and it should be set in a consensus conference of experts with due consideration of the social good.
The ethical waters do quickly become murky when we accept proxy consent or advance directives in research, or when we consider increasing the amount of risk an incapacitated subject may be asked to incur in support of some socially desirable outcome. When we do that, it becomes increasingly important to maintain other forms of respect for autonomy. A free consent can be withdrawn at any time. To maintain the freedom to withdraw, either the proxy or a ''monitor'' or ''research intermediary'' must be continuously involved on behalf of the incapacitated subject (Kapp, 1998). Monitors or proxies, along with the investigator, in such situations must watch for not only the best interests of the subject but also for the subject's continued assent to participate. Even a subject who is not cognitively able to consent to participate may at any point resist continued participation or express a strong preference for withdrawing, and such preferences should be noticed and honored.
In summary, there is ethical agreement that older adults should be able to consent or refuse to consent to participate in research, even if that requires some additional assistance. There is also agreement that incapacitated persons deserve special protection. The question is still open on whether the goal of controlling or eliminating diseases that affect older adults can be a societal good so important that it justifies increasing the maximum permissible risk to subjects who cannot consent.
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