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Adults with Diminished Capacity

Published on Apr 05, 2022 · Last Updated 2 months ago


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When an adult does not have the capacity to consent to the procedures involved in the research, then they cannot participate without the consent of their legally authorized representative (LAR). In Pennsylvania, a competent adult may designate an individual of their choice to serve as their LAR, such that if that individual loses the ability to consent due to a temporary situation (surgery, trauma), their LAR may act on their behalf. Someone with a progressive condition such as Alzheimer's can also designate an LAR before they lose the competence to consent. Other adults may have conditions that are associated with ongoing impaired decision-making capacity related to their illness or disorder or developmental or cognitive impairment.

Since most individuals seen and cared for at CHOP are children, adults with diminished capacity are, for the most part, patients with neurological impairment (associated with congenital, genetic, traumatic, progressive or other disorders) or developmental disorders (e.g., intellectual disability, autism spectrum disorder, or other), whose care has extended from childhood into adulthood. The investigator must develop a plan to determine whether or not the prospective adult subject has the capacity to consent and if they do not, there must be a method to determine whether there is a designated LAR who can consent on the adult's behalf.

How can one determine if the subject (or the parent of the subject) has the capacity to consent?

Incompetence to consent to medical treatment

Under Act 169 incompetent means condition in which an individual - despite being provided appropriate medical information, communication supports, and technical assistance - is unable to:

  • Understand the potential material benefits, risks, and alternatives involved in a specific proposed health care decision;
  • Make that health care decision on his own behalf; or
  • Communicate that health care decision to any other person.

These findings must be documented by the healthcare worker. The term is intended to permit individuals to be found incompetent to make some health care decisions, but competent to make others.

If an individual meets the legal requirement for competence, then they must consent to their own participation in the research. Children lack the legal status to consent and therefore, parents must consent (give their permission) on the child's behalf.

The November 30, 2006 Act 169 on Advanced Directives defines which adults are competent to consent to treatment and which are incompetent. Individuals who are competent to make their own treatment decisions have the capacity to consent to research.

Clinical Care vs Research:
Many individuals who lack the competence to consent to treatment still retain the capacity to consent to research. For example, an adult with diminished capacity may lack the ability to manage their daily affairs and the complexity of their required healthcare treatment. They might however, have the ability to understand the purpose, procedures and other elements of consent for a minimal risk research study, such as one involving a blood draw or a questionnaire.

An individual who has the capacity to consent to participate in a minimal risk study might not have the capacity to comprehend all of the components of a randomized trial. They might however, understand enough to assent to their own participation after their LAR granted permission for them to take part.

Ultimately the investigator is responsible for ensuring that all prospective subjects (LARs of subjects) understands the required information in the consent form sufficiently to provide informed of consent. Those that do not, should not take part.

Formal Assessment of Capacity

Basic elements of consent

  • Purpose of the study
  • Procedures required
  • Duration of participation
  • Risks
  • Benefits - direct and indirect
  • Voluntariness of participation including freedom to withdraw
  • Alternative treatments or procedures (if applicable)
  • Who to contact with questions
  • Confidentiality of data
  • See Basic Elements of Consent for a more detailed explanation of the elements of consent.

Talk Back:
After reviewing the consent form, the investigators can use Talk Back to assess comprehension. Questions should be open-ended and should not involve yes or no questions. Examples are included below. When there are areas of misunderstanding, the investigator is obligated to review and re-explain that aspect of consent.

  • "What did you understand to be the purpose of research?",
  • "What procedures will you need to undergo?",
  • "What is the chance that you'll get the study drug/placebo?"

A post-consent questionnaire can be used to assess subject comprehension. There are a variety of standard tools that have been developed that can be adapted to the complexity of the study.

Generic Plan for Adults who Potentially have Diminished Capacity to Consent:

The IRB has developed a generic plan that can be adapted to the requirements of the study protocol for adults who might have diminished capacity. This plan should be included in the Informed Consent section of the protocol.

Additional Tools


  1. Appelbaum PS, Roth LH. Competency to consent to research: a psychiatric overview. Arch Gen Psychiatry. 1982;39:951-958.
  2. Chen DT, Miller FG, Rosenstein DL. Enrolling decisionally impaired adults in clinical research. Med Care. 2002;40:V20-V29.
  3. Simpson C. Decision-making capacity and informed consent to participate in research by cognitively impaired individuals. Appl Nurs Res. 2010;23:221-226.
  4. Miller CK, O'Donnell DC, Searight HR, Barbarash RA. The Deaconess Informed Consent Comprehension Test: an assessment tool for clinical research subjects. Pharmacotherapy. 1996;16:872-878.
  5. Tait AR, Voepel-Lewis T, Malviya S. Do they understand?(part I): parental consent for children participating in clinical anesthesia and surgery research. Anesthesiology. 2003;98:603.

Who can serve as the adult's legally authorized representative (LAR)?

Definition of a Legally Authorized Representative (LAR)

45 CFR 46.102(c) Legally authorized representative means an individual or judicial or other body authorized under applicable law to consent on behalf of a prospective subject to the subject's participation in the procedure(s) involved in the research.

The issue as to who can be an LAR is determined by the laws of the jurisdiction in which the research is conducted (e.g., local or state law). Some states have statutes, regulations, or common law that specifically address consent by someone other than the subject for participation in research. Most states, including Pennsylvania, don't have laws to specifically addressing the issue of consent in the research context. In Pennsylvania therefore, the laws that address who is authorized to give consent on behalf of another person to specific medical procedures or generally to medical treatment may be relevant if the research involves those medical procedures or medical treatment.

What is the priority order when an LAR has not been designated?

PA Act 169: Priority Order to Serve as an LAR

Unless an individual has designated otherwise, their health care representative will be determined by a statutory list that generally gives priority in the following order:

  • spouse and adult child who is not the child of the spouse
  • adult child
  • parent
  • adult sibling
  • adult grandchild
  • close friend

OHRP Guidance states that "When the laws of the jurisdiction in which the research is being conducted provide a reasonable basis for authorizing an individual to consent on behalf of a prospective subject to their participation in the research procedure(s), OHRP would consider such an individual to be an LAR as defined by HHS regulations at 45 CFR 46.102(c). IRBs may wish to consult with legal counsel when deciding who can serve as an LAR for subjects of proposed research."

In Pennsylvania, PA Act 169 (Advance Directives) establishes the priority order of individuals who may serve as the LAR in situations where the incompetent individual has not designated an LAR. For most CHOP subjects, the LAR will be the participant's parent(s).