As a person ages, driving skills change due to both muscle and vision degeneration, slowing reaction time, and the effects of illnesses and medications. Although older drivers are among the safest drivers in the United States, car crashes are the leading cause of injury-related fatalities in 65-74 year olds and the second leading cause of fatalities for those 75 years of age or older, after falls. In 1995, one out of every 11 drivers was over age 70. By the year 2020, one out of every 5 drivers will be over age 65.
Studies suggest that older drivers with dementia are at greater risk for accidents compared to other drivers. On-road tests of driving skills have shown that drivers with mild dementia were more prone to errors than a control group. Other surveys note that drivers with dementia had twice as many "close calls" as other drivers, perhaps because they have significant problems, for example, in processing visual information.
Although studies have analyzed this problem in different ways - for example, dementia has been classified using different measurement scales - almost all studies point to the same general conclusion: drivers with dementia should undergo regular, on-road testing of skills to ensure safety of the driver, passengers, and others. When should a person with dementia due to Alzheimer's disease stop driving? Is a diagnosis of AD an automatic signal that a driver's license should be surrendered?
While there are no "right" answers to these questions, recent studies suggest that a diagnosis of mild or early-stage AD is not necessarily the moment that a driver's license should be forfeited. People with mild dementia sometimes can continue driving safely, but their caregivers should monitor driving closely, because the progressive nature of dementia will eventually affect driving ability. In addition to the normal process of aging and its effects on driving, dementia slowly erodes cognitive functions critical to driving, including attention, judgment, reaction time, spatial skills, and problem-solving abilities.
Once a diagnosis of dementia has been made, regular assessments of driving capability should be conducted by trained staff at the State motor vehicle department. Even if the person with dementia demonstrates safe driving, driving should gradually be limited to avoid more challenging situations, such as heavy traffic, unfamiliar roads, night driving, or long distance highway driving.
Many of the general symptoms of Alzheimer's disease affect driving ability, including:
Symptoms of dementia can lead to the following dangerous driving situations, which could cause a serious accident, fender bender, or near miss:
Doctors are perceived as authority figures whose opinions may be taken more seriously than those of a caregiver or family member by the person with dementia. According to the American Academy of Neurology, patients and their families should be informed that patients with AD with a Clinical Dementia Rating (CDR) of 1 or more have a higher crash rate, and therefore should not drive. A CDR of 0.5 can cause driving safety problems when compared to other older drivers, thus a referral to a trained examiner for evaluation of driver skills should be considered. Reevaluation every 6 months is recommended. A CDR stage 1 is roughly equivalent to a Mini-Mental State Examination (MMSE) score of less than 25 but greater than 19; a CDR of 0.5 is roughly equivalent to an MMSE score of 25 or greater.
During the appointment, a physician should evaluate the patient's physical condition, cognitive skills, and medication use, and should take a thorough driving history, including:
If patients are clearly a risk to themselves or others, the physician should take action to "prescribe" that driving cease, using the prescription pad. The discussion should be open and sensitive to the issues involved, particularly the perceived threat to independence. The discussion should be noted in the patient's medical record. The physician should be prepared to offer advice on available alternative forms of transportation and counsel the patient on ways to cope without a car, according to the American Academy of Family Physicians. It's also a good idea for the doctor to follow-up with the caregiver to see if his or her advice is being followed.
Although physicians may find themselves in an ethical dilemma about whether to maintain patient confidentiality, or report driver impairment to legal authorities, their overall goal should be to prevent injury. In some States, physicians are even required to report patients who are no longer capable of driving. If a patient refuses to stop driving despite advice from the physician, the physician can consider a referral for further testing or additional opinions. An on-road test administered by trained personnel is considered the best overall method to evaluate driving abilities.
The National Institute on Aging and the National Highway Traffic Safety Administration (NHTSA) are teaming up to fund studies of how Alzheimer's disease affects the ability to drive. One such effort at the Washington University at St. Louis Alzheimer's Disease Center (ADC) will gather opinions on driving with dementia from people with early, mild-stage AD, caregivers, members of advocacy organizations, health care professionals, and insurance experts. This information will help guide the NHTSA in an education campaign. Strategies on how and when to stop driving will also be developed. The Rush-Presbyterian-St. Lukes Medical Center ADC in Chicago is also funded by this NHSTA and NIA grant.
Washington University ADRC Co-Director Dr. John Morris, recently stated, "Some persons with dementia, especially those in the very mild stages, often continue to drive safely, at least for the time being. Some prevailing attitudes are at odds with this viewpoint, however, and support that driving cessation occur at the time dementia is diagnosed, regardless of the driving ability of the individual. The challenge is knowing when and how to initiate a driving cessation process when driving is no longer safe. Our study will begin to address some of these issues by talking to the people most involved."
Carr, David B. (2000). The Older Adult Driver. American Family Physician, 61(1), 141-150. Internet: www.aafp.org/afp/20000101/141.html .
Dubinsky, Richard M.; Stein, Anthony C.; Lyons, Kelly. (2000). Practice Parameter: Risk of Driving and Alzheimer's Disease: An Evidence-Based Review. Neurology, 54, 2205-2211.
Foley, Daniel J.; Helmovitz, Harley K.; Guralnik, Jack M.; Brock, Dwight B. (2002). Driving Life Expectancy of Persons Aged 70 Years and Older in the United States. American Journal of Public Health, 92(8). 1284-1289.
Kakaiya, Ram; Tisovex, Richard; Fulkerson, Phillip. (2000). Evaluation of Fitness to Drive. The Physician's Role in Assessing Elderly or Demented Patients. Postgraduate Medicine, 107(3), 229-236.