Decisionally Impaired Participants


Research that involves adults with limited decision-making capacity due to physical or mental impairment covers a broad spectrum. Limited decision-making capacity may include conditions such as head injuries, moderate to severe Alzheimer’s disease, mental retardation, mental illness associated with psychosis, or other conditions associated with impaired judgment.

Researchers should be sensitive to the differing levels of capacity and use assessment methods tailored to the specific situation. They should also carefully consider the timing of assessment to avoid periods of heightened vulnerability when individuals may not be able to provide valid informed consent.

People with limited decision-making capacity can participation in research, but additional scrutiny by the Institutional Review Board (IRB) and researchers is warranted for research involving this population. Special protections are essential to guide research involving such vulnerable persons, but it is also critical to acknowledge that ethical harm may result by excluding persons who lack capacity to consent from the opportunity to participate in research.

A subject demonstrates a lack of decision-making capacity when a physician or researcher demonstrates that the patient is unable to understand:

  • A proposed research procedure, treatment, intervention, or interaction.
  • The risks and benefits of such procedure, treatment, intervention, or interaction.
  • The risks and benefits of any available alternative to the proposed procedure, treatment, intervention, or interaction.

In all human research, varied degrees of research risk and decisional impairment call for varied levels of scrutiny and safeguards. Treating all individuals who have cognitive deficits as incapable of understanding research is inaccurate, and disrespectful of their autonomy. Many individuals, adequately informed, may be willing to undertake certain risks so that they or others may benefit in the future.


While no specific set of criteria can encompass all conceivable situations in which the use of surrogate consent complies with the intent of the Common Rule (45 CFR 46), the following standards should be followed when obtaining surrogate consent for adults to participate in a research study:

Surrogate consent is a protocol-specific request of the investigator and must be reviewed and approved accordingly by the IRB. Depending on the nature and risks of the research, the IRB may require consent from the subject’s legally authorized representative.

Surrogate consent is requested through the application process for new research studies or through the modification process for an existing protocol.

The investigator shall include in the IRB application/modification form a protocol-specific plan for the assessment of the decision-making capacity of the subject.

If an adult is cognitively incapacitated or impaired due to mental or physical conditions, including Alzheimer’s disease, consent to participate in research may be authorized by an adult who has decision-making capacity. In order of priority, such a person may be:

  • The court-appointed legal guardian of the subject; the individual who has the durable medical power of attorney that specifies ability to consent for research on behalf of the subject; or the individual who has the durable medical power of attorney for a subject participating in a clinical trial or a study that holds the potential for medical benefit to the subject.
  • The subject’s spouse.
  • An adult child of the subject who has the waiver and consent of all other qualified adult children of the subject to act as the sole decision-maker.
  • A majority of the subject’s reasonably available adult children.
  • The subject’s parents.
  • The individual clearly identified to act for the subject by the subject before the subject became incapacitated; the subject’s nearest living relative, or a member of the clergy.

The surrogate decision-maker may not consent to:

  • Voluntary inpatient mental health services.
  • Electro-convulsive treatment.
  • The appointment of another surrogate decision-maker.

Even when use of surrogate consent is approved by the IRB, investigators must attempt to obtain informed consent directly from the potential subjects whenever possible. Should a potential subject be sufficiently incapacitated as to be unable to give informed consent, consent may be obtained from a qualified surrogate (see list above). The investigator shall make a notation in the medical record and on the informed consent document indicating the reasons why surrogate consent was employed and the relationship of the surrogate to the subject.

Surrogates should be informed of the risks, benefits, and alternatives to the research when they are providing permission for an individual to participate. Whenever possible, surrogates should make research decisions based on substituted judgment, reflecting the views of the individual expressed while decisionally capable, or in the best interest of the subject.

It is essential that the consent process and documents clearly indicate differences both between individualized treatment and research, and between clinician and clinical investigator.

Surrogates should be available throughout the conduct of the study to monitor the subject’s recruitment, participation, and withdrawal from the study.

The autonomy of individuals with impaired decision-making capacity should be respected. Their assent to participation in research should be obtained whenever possible and their decision to withdraw from a study at any time should be honored.

If the subject expresses resistance or dissent to participation or to the use of surrogate consent by word or gesture, the subject shall be excluded from the research study.