Research Ethics Program Core (REP)

Research in the Cognitively Impaired

An outline for a process for informed consent in research that involves persons with cognitive impairment.

When is a process necessary for capacity assessment?

To some, this question may seem a trick question. The answer is "always" or at least whenever informed consent is required. Informed consent is the voluntary choice of the competent person. Only after a capacity assessment can one determine that a person is competent.

Perhaps the issue is the structure and rigor of the capacity assessment. A reasonable principle is that the degree of this structure and rigor should be proportional to the vulnerability of the subject population.

By "vulnerable" we mean the degree to which the subjects are relatively or even absolutely incapable of protecting their rights and interests. One kind of vulnerable subject population is persons with cognitive impairment.

When are adults with cognitive impairment vulnerable?

Persons with cognitive impairment are vulnerable if a reasonable clinician would agree that these impairments might impair their ability to perform their usual and everyday activities, such as managing their medications or money, using the telephone or negotiating transportation. Examples of such diseases include Alzheimers Disease, head trauma or critical illness.

Studies that investigate the capacity of persons with these kinds of diseases show that their cognitive impairments may be severe enough to impair their decision making capacity. Investigators who conduct studies that enroll these kinds of persons should consider whether potential subjects need a structured assessment of their capacity.

Adults with cognitive impairment may also be vulnerable because of where they live. In particular, persons who are in a situation that does not allow them the freedom to move as they see fit, such as a nursing home or a hospital, may not have sufficient freedom or voluntariness to make a decision.

Adults who do not have cognitive impairment may be vulnerable if they cannot read or at least read at the reading level of the information disclosed on the informed consent form. For example, a person who has an eight grade reading level very well will have impaired capacity if the form is written at a 12th grade level. Of course, the investigator can correct this lack of capacity by writing the form at an 8th grade level.

What is decision making capacity?

Decision making capacity describes a person's ability to make a decision. Like weight or blood glucose, it is a dimensional construct and its dimensions are described by the decision making abilities.

There are at least four abilities. The ability to choose among options. The ability to reason about that choice, for example, explaining how the choice could affect your daily activities. The ability to understand information disclosed to you. And, the ability to apply that information to your situation, also known as appreciation. Decision making capacity lies along a continuum from complete capacity to no capacity what so ever.

Can decision making capacity be measured?

Yes, it can. There are several techniques to measuring capacity. They can range from an informal interview to a structured assessment that uses an instrument to measure each of the decision making abilities.

How much structure should an investigator expect in a capacity assessment?

Informed consent is a subject protection. It is intended to assure that a person is getting involved in a project they want to get involved in and they are not involved in a project they don't want to get involved in.

It is reasonable then that the nature of the structure of a capacity assessment depends on the risks and hassles of the research. Specifically, as the risks and hassles increase, an investigator should consider increasing the structure of the assessment.

What are some ways to structure a capacity assessment?

In the case of minimal risk, low hassle studies, the assessment would likely be a few open ended questions that assess understanding of the key information: this is a study, its risks, key procedures. The persons administering informed consent asks these questions after reviewing the informed consent form.

In the case of more than minimal risk, or high hassle studies an investigator should consider preparing a key points sheet that summarizes the key facts disclosed in the informed consent form and having a quiz to assess a person's understanding of the key points. The investigator can then review that quiz with the person. The quiz is open book, that is they have the informed consent form and key points with them.

The quiz is not an end in itself. The review of the answers and errors informs the judgment whether the person has sufficient capacity to provide his or her own informed consent.

Do you always ned to assess all four decision making abilities?

No. You at least need to make sure the person can make a choice and he or she understands the information. But whether the person needs to appreciate the information or reason through it may not be necessary. That depends on the risks of the research and concerns about therapeutic misconception, a term that describes mistaking research procedures as personal care done to benefit the patient.

For example, a study may involve randomization. An investigator may want to make sure the subject not only understand what is randomization but also appreciates that in this study they will have their study drug assigned by a flip of a coin. A subject who thinks the investigator will select treatment appropriate for them shows a lack of appreciation for randomization.


What facts do you assess in a capacity assessment?

The assessment of capacity focuses on assessing a person's understanding of the facts. The facts to assess are the nine items that the Common Rule requires an investigator disclose in an informed consent form. Of course, not all studies require all nine items. For example, if the study is minimal risk and low hassle, you likely do not need to assess understanding of all those elements that must be disclosed. A useful rule is to focus on what a reasonable person needs to know.

What do you do if you find that the person lacks the ability to give his or her own informed consent?

You need to have a procedure in place to identify a person who will provide informed consent for that person. Typically, we call this person a proxy or a surrogate. Often, they are a family member such as a spouse, partner or adult child. Commonly, they are the same person who serves in the role of a proxy for medical care decisions.

You should consider the qualities that qualify a person as a good proxy:

  • Is familiar with the person's health and health care needs
  • Has some experience making health care decisions either with or for that person
  • Has helped that person with the activities of daily living

Of course, in research that involves persons who have acutely suffered cognitive impairment, such as head injury, there may not be a person who fits into these roles. In such a a case, it is sensible to seek out the person who would be legally authorized to make medical decisions for that person, such as a spouse/partner or close family member.

Some additional precautions to consider. A subject who has cognitive impairment who is able to provide his or her own informed consent may over time loose the ability to continue to make decisions with the investigator. If this is a reasonable over the course of your study, consider asking the subject to designate a person he or she would like to serve as a proxy.