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Medical Decision-Making Capacity of Patients With Dementia

Medical Decision-Making Capacity of Patients With Dementia

The United States Census Bureau projects that by 2010 nearly 13% of the US population will be over the age of 65. The elderly are one of the most rapidly growing segments of the US population and are expected to account for more than 20% of the total population by 2050.1 In 2001, the prevalence of dementia in North America was 6.4%. A 49% increase in the number of people with dementia is expected by 2020, and a 172% increase by 2040.2 Patients with dementia may lack the capacity to consent to treatment. The need to evaluate capacity to consent to treatment will therefore increase as the aging population grows.


Mrs E, who is 80 years old, lives in the community with the help of a 24-hour-a-day home health aide. She is forgetful and requires assistance with many activities of daily living.

Mrs E is brought for evaluation because she has been crying more frequently. She remains in bed for most of the day, does not engage in activities she used to enjoy, and is sleeping and eating less than usual. The doctor recommends a trial of an antidepressant, which Mrs E refuses. She states, “I’m 80 years old and I’m not about to start taking medications now. That would kill me!”

How can her doctor determine whether she has the capacity to refuse treatment for depression?

In 1990, Congress passed the Patient Self-Determination Act (PSDA). The PSDA requires many Medicare and Medicaid providers—including hospitals, nursing homes, hospices, and HMOs—to give patients information about their rights, including their right to accept or refuse medical or surgical treatment. The law clearly intends that residents of nursing homes retain their right to accept or refuse treatment. Our society places a high value on an individual’s autonomy by generally allowing people to make decisions for themselves, even if the decisions confer the risk of substantial harm (for example, bungee jumping).

Many of the rights that we take for granted derive from the legal concept of a “liberty interest” that protects individuals from unwanted intrusions on their person. Some people question whether a person with dementia should retain this sense of self and autonomy or whether family members should make medical decisions for him or her. During the past 10 years, there has been an increased recognition that persons with dementia retain a sense of self, complete with preferences, despite cognitive loss.3

There are many safeguards in place to protect a person’s independence. In particular, the doctrine of informed consent for medical treatment has been designed to preserve a patient’s autonomy by limiting the doctor from touching, operat-ing on, medicating, or exerting control without the patient’s expressed agreement. This doctrine applies to all persons, including patients with dementia.

How much information is too much information?

Informed consent in a medical context consists of 3 elements (Table 1): disclosure of information, voluntary acceptance of treatment, and mental capacity. In this article, we discuss whether patients with dementia can offer informed consent for treatment and how physicians can negotiate such consent.

Let us first examine the primary element of informed consent: information. How much and what kind of information should the physician share? Does it help the patient to know that 1 in 1000 patients experience a particularly serious adverse effect? What if 1 in 100 patients has a minor reaction: would that change whether the patient should be told about the potential adverse outcome?

Two landmark court cases have clarified how much information should be provided. First, the court in Natanson v Kline established that the clinician should provide information that the “reasonable medical practitioner” would customarily disclose to a patient.4 Later, in Canterbury v Spence, a court shifted its position and ruled that the doctor should provide information that a “reasonable person” would want to know in order to decide whether to accept or refuse the proposed treatment.5 This shift from what the reasonable practitioner would discuss to what the reasonable person would want to know directed the clinician to consider knowledge of the patient’s specific circumstances and mental state.

It is acceptable for physicians to exercise therapeutic privilege and withhold certain information at their discretion if they deem that the information would pose a serious psychological threat by cognitively overwhelming the patient or causing panic.


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