Medical Decision-Making Capacity of Patients With Dementia

Consent must be voluntary

The second element of medical informed consent is that the patient’s consent be given voluntarily. This implies that the patient’s decision is free from coercion. Coercion can be obvious—as in the case of an institutionalized patient who is told that she will have to continue wearing hospital gowns until she takes her medication—or it can be subtler—as in the case of a physician whose policy is to complete disability paperwork only for patients who agree to the proffered treatment. In both cases, coercion interferes with the patient’s ability to freely give informed consent.⁶ When examining patients with cognitive deficits, it is important to recognize that the more emotionally dependent and cognitively impaired they are, the more susceptible they are to even subtle coercion.⁷

Capacity to consent to treatment

The third essential element in the informed consent process—the capacity to consent to treatment—is the most crucial aspect for the clinician to consider (Table 2). To be considered capable of consenting or refusing treatment, the patient must be able to:

• Communicate a clear choice without vacillating significantly.

• Demonstrate a factual understanding of the medical issues at hand, including the risks and benefits of the treatment and any reasonable alternatives.

• Show comprehension of the situation as it applies to him and the consequences of his decisions. This implies that the patient has psychological insight into his illness and need for treatment.

• Display a rational manipulation of the information presented with a coherent and logical thought process in analyzing the various courses of action. This element examines the process and not the content of the person’s thoughts.⁸

People are allowed to make decisions that are contrary to their physician’s best advice, as long as all 4 of these criteria are met. For example, if a person with depression and mild dementia takes an acetaminophen overdose in a suicide attempt, he can be retained in the hospital on an emergency basis because he poses a threat to himself. However, he may or may not have the capacity to refuse medical treatment regardless of his involuntary status. Establishing a patient’s capacity to consent to treatment protects the patient’s presumed autonomy while protecting those whose cognitive impairment precludes the ability for meaningful and lawful consent.

Dementia, delirium, depression, psychosis, and drug intoxication, along with other psychiatric syndromes, can affect a person’s capacity to provide consent for treatment. Conversely, having any one of these conditions does not, per se, indicate a lack of capacity to consent to treatment.

Each person must be evaluated to determine whether he has the capacity to consent to the specific treatment at a particular time in the course of his illness. Patients with severe and chronic dementia, those who have a Mini-Mental State Examination (MMSE)⁹ score of less than 16, have a high likelihood of being unable to consent to treatment. One study of 98 patients with Alzheimer-type dementia found that only 11% of the patients with MMSE scores of less than 16 retained decision-making capacity.¹⁰

Other studies have found that patients who have mild cognitive impairment (ie, those with episodic memory impairment who do not meet criteria for dementia) are more likely than those without cognitive impairment to have impaired decision-making capacity. Mild cognitive impairment can erode the ability to remem-ber, understand, and apply medical information that has been presented, thereby impairing decision-making capacity while leaving the person relatively intact during activities of daily living.¹¹

Other investigators have noted that patients with mild cognitive impairment frequently display deficits in executive functioning, specifically in areas of abstract thinking and cognitive flexibility. These deficits also degrade decision-making capacity, especially understanding the conse-quences of a treatment choice.^12,13

The Clock-Drawing Test, which consists of asking the patient to “please draw a clock, fill in the numbers and set the time to 10 past 11,” is a useful screening tool because it tests a number of cognitive skills: comprehension, planning, abstract thinking, and executive function.¹⁴ Cognitive screening tests may help identify patients who need a more extensive evaluation of their capacity to consent to treatment, but they cannot be relied on to determine the ability to consent.