Alzheimer's and Driving Ability

Content provided by the Faculty of the Harvard Medical School

Knowing when it may be time for someone to surrender the car keys.

As people grow older, their vision, hearing, reflexes, strength, flexibility, and coordination tend to deteriorate. These physical changes can undermine driving skills, such as being able to see and hear other vehicles, stop suddenly, navigate an intersection safely, or maintain control of a car. Alzheimer's disease only compounds age-related challenges by impairing memory, insight, and reasoning.

As Alzheimer's progresses, for instance, a patient may have trouble remembering how to get somewhere, or may become confused (such as stopping at a green light or stepping on the gas pedal instead of the brake).

Although most experts agree that anyone with moderate to severe Alzheimer's or another dementia should stop driving, no consensus exists about patients at earlier stages of cognitive decline. The American Academy of Neurology and the American Association for Geriatric Psychiatry both recommend that patients with mild dementia stop driving. The Alzheimer's Association, however, believes that the determination should be based on driving ability rather than a medical diagnosis.

Rates of deterioration

To better determine the rate at which driving skills deteriorate in people with early Alzheimer's, researchers at Brown University conducted a longitudinal study of 128 drivers, consisting of 84 patients with early Alzheimer's and 44 healthy older drivers who served as controls. The average age was 75. Patients with a clinical dementia rating (CDR) of 0.5 were diagnosed with very mild Alzheimer's, while those with a CDR of 1 were diagnosed with mild Alzheimer's. The researchers excluded patients with moderate or severe dementia, as well as those with mild cognitive impairment (which raises the risk of Alzheimer's).

All healthy controls passed an initial on-road driving test, compared with 88% of patients with very mild Alzheimer's, and 78% of those with mild Alzheimer's. At a subsequent road test 18 months later, driving skills in all participants — even healthy controls — had deteriorated, and many patients had stopped driving for safety reasons. However, patients with mild Alzheimer's became unsafe drivers about twice as fast as those with very mild Alzheimer's, based on tests conducted every six months. Patients with mild Alzheimer's failed the driving test after a median of 324 days (roughly 11 months), while those with very mild Alzheimer's failed the test after a median of 605 days (roughly 20 months).

The findings confirm earlier results of a longitudinal study by researchers at Washington University in St. Louis. This suggests that patients with mild Alzheimer's may be able to continue driving safely for a time. But it's important for clinicians, family members, and drivers themselves to remain vigilant for signs of deterioration and to reassess skills regularly.

Resources

These organizations offer checklists for risky driving behavior and advice about how to have a conversation with a patient about driving.

AARP www.aarp.org

Alzheimer's Association www.alz.org

American Automobile Association www.aaa.com

American Medical Association Older Driver Safety www.ama-assn.org/ama/pub/category/8925.html

The Hartford/Massachusetts Institute of Technology AgeLab Partnership Family Conversations About Alzheimer's Disease, Dementia, and Driving www.thehartford.com/alzheimers

Having the conversation

Checklists of risky driving behaviors are readily available (see "Resources"). Patterns of behavior, rather than isolated incidents, are what signal a need for intervention.

Of course, the real challenge is to convince patients who lack insight — or who are stubbornly independent — that it's time to stop driving. Here are some tips on how to handle the situation:

Start the discussion early. As soon as a patient is diagnosed with Alzheimer's or another type of dementia, it's important for clinicians and family members to begin the conversation about driving. This can be broached while discussing other aspects of care.

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More than 5.3 million people in the United States are living with Alzheimer's disease, with a new person developing the disease every 70 seconds. Americans ages 65 and older with Alzheimer's and dementia pay three times as much in health care costs.