The federal regulations pertaining to the protection of human subjects in research require that researchers obtain informed consent from subjects or their legally authorized representative. Participants must be adults (persons 18 years or older) to consent. However, there are times when adults may not have the capacity to consent, either due to incapacitation, cognitive disability, contextual constraint, or economic/social disadvantage. 

In some cases, an individual's ability to provide informed consent may diminish or improve depending on their current mental or physical state. Conditions affecting one’s capacity to consent may include dementia or cognitive impairment, psychosis or psychotic symptoms, and abnormal behavior, presenting with degrees of confusion, forgetfulness, or difficulties in communication. 

There are times when adults may not have the capacity to consent, either due to incapacitation, cognitive disability, contextual constraint, or economic/social disadvantage.

Using professional training and ethical engagement, researchers should assess potential participants’ cognitive awareness and decision-making capacity in the current context prior to engaging in the consenting process. When adults are not competent to consent, a legally authorized representative may consent on behalf of the individual, so long as they keep the individual’s best interest and personal wishes in mind.

Assessment of Capacity to Consent

Even if individuals have demonstrated diminished capacity in the past, researchers should still presume capacity to consent, unless proven otherwise. Researchers should carefully assess an individual’s capacity to consent using evidence-based standards that are relevant to their population of interest and are based on a list of justifiable and reasonable standards. 

Justifiable and Reasonable Standards for Assessing Capacity

1. Did the individual make a choice? 

  • This question assesses whether the individual can make consistent, clear choices about participating in a study. If the individual is ambiguous, confused, or their choice to be in a study oscillates between understanding and bewilderment during the course of the assessment process, they are not capable to provide informed consent. 
  • One way to assess decision-making abilities is to ask at various parts of the recruitment and consenting process whether the individual would like to participate in the research study. The researcher should also ask if the individual understands what is being asked of them, or if they need any clarification. The potential research subject should answer clearly and affirmatively at every step.
  • Researchers should clarify that the study is voluntary and the individual is not required to participate. The individual always has a choice. Researchers may ask the following questions to assess whether the individual knows that participation is voluntary:
    • Question: “Do you have to participate in this study?”
      • Answer: “No, this study is voluntary. I do not have to participate."
    • Question: “If you do not participate in this study, will anything happen to you? Will you lose access to resources or services due to you?”
      • Answer: “No, this study is voluntary. Nothing bad will happen if I choose not to participate.”
    • Question: “If you choose to participate now but change your mind later, what will happen?”
      • Answer: “I can change my mind or stop participating at any time.”
    • Question: “Do you have a choice to stop participating in the study?”
      • Answer: “Yes, I always have a choice. I can choose to participate, and then change my mind at any time.”

2. Did the individual show understanding?

  • When the researcher explains the study, the potential participant should demonstrate an awareness and comprehensive understanding of the study expectations. The researcher should clearly convey (1) that study participation is voluntary, (2) study activity expectations, including time requirements, (3) anticipated risks of participating in the study, and (4) any benefits.
  • Researchers may ask the following questions to assess understanding:
    • “What will you be asked to do as part of this study?”
    • “Are all parts of this study required?”
    • “Can you leave the study at any time?”
    • “Do you have to participate in this study?”
    • “If you choose not to participate will anything bad happen to you?”

3. Did the individual show reasoning abilities? 

    • The individual should have the ability to compare the study’s risks and benefits and logically conclude whether they want to participate. Researchers can ask the individual if they have questions or need further clarification. The researcher should give ample time for the individual to consider whether or not they wish to participate. 
    • The participant should be able to describe the risks and benefits and weigh them against each other. They should acknowledge how the risks will affect them, or how the benefits may outweigh the risks in their decision to participate. Researchers may ask the following series of questions to ensure reasoning capabilities:
      • “Tell me about the risks involved with being part of the study.”
      • “Tell me about the benefits involved with being in this study.”
      • “Considering the risks and benefits, would you like to take part in this study?” 
      • If the individual states affirmatively, ask, “Knowing the risks, why do you still want to take part in this study?” 
      • “Do you have any questions about the risks or benefits of this study?” 

    4. Did the individual show comprehension of the risks and benefits of the study?

    • When learning about the risks and benefits, the individual should demonstrate a realistic, analytical comprehension of how those risks and benefits apply to their particular situation. Researchers should provide examples or comparisons (e.g., “this study activity is similar to taking a math test in school” or “wearing this device is similar to wearing a watch on your wrist”) to help convey risks and benefits.
    • Researchers may want to ask individuals, “How might this study (activities, benefits, and/or risks) impact you?”

    If an individual is not determined to be capable of consent with regard to even one of the standards, a legally authorized representative should be consulted and the individual should be asked to provide assent, rather than consent. Note that these standards were developed by the UC Davis Alzheimer’s Disease Center and may not apply to a researcher’s specific population of interest. TC IRB will evaluate assessment standards on a case-by-case basis, taking into account the potential participant’s context and resources, demographic characteristics, study activities, etc.

    Proposing to Use the Capacity to Consent Assessment in Research

    Researchers who wish to incorporate this “capacity to consent” assessment into their recruitment process should adapt it to meet the setting, context, and situation of their population of interest. After the assessment has been approved by the IRB, the researcher should record the individual’s responses to the assessment questions, and their determination at the time of assessment (e.g., “participant capable to provide consent” or “participant not capable to provide consent; legal guardian permission sought”). 

    When submitting an IRB protocol for review that includes such an assessment, the researcher should outline the questions for potential participants and the criteria for determining their capacity, keeping respect for the participants’ well-being at the forefront of the study design. Researchers will also need to develop:

    1. A consent form (e.g., Informed Consent Form Template) for participants who are determined capable of consenting,
    2. An assent form (e.g., Assent Form Template) for participants who are deemed ineligible to consent, and
    3. A legally authorized representative form (e.g., Parental Permission Form Template) for the guardians of participants who are deemed ineligible to consent. 

    All documentation (as needed) should be uploaded with an IRB protocol submission to Mentor IRB. For more information on the submission process, please review our New Protocol page.

    Resources

    — Kailee Kodama Muscente, M.A., M.Ed.

    Tags: Consent Recruitment Tips for Success Ethics

    Published Tuesday, Aug 2, 2022