An estimated 36 million people worldwide are currently living with dementia.1 A 2015 evaluation by Vaughan and colleagues2 of participants in the Women’s Health Initiative Memory Study-Epidemiology of Cognitive Health Outcomes (WHIMS-ECHO) reported that 60% of women assessed with mild cognitive impairment (MCI) and 40% diagnosed with dementia were still driving.
The clinical problem is 2-fold: first, determining the point at which driving ability is compromised enough by dementia to increase the risk of accidents, and second, taking action to stop someone from driving when they have driven their whole adult lives. No formal mechanisms exist in the United States or other countries to require retesting of driving skills or mandatory cessation of driving for reasons associated with dementia, and so the treating neurologist is often relied upon to initiate discussions of driving, with little or no preparation.
“Many of the providers have never had the opportunity to be trained in how to talk to patients about driving,” explained Joshua Chodosh, MD, the Michael L. Freedman Professor of Geriatric Research in the Department of Medicine, Division of Geriatric Medicine and Palliative Care, and professor in the Department of Population Health at NYU Langone Health Systems. “That’s a pretty loaded subject. Driving may be the one thing patients have where they still have control and authority. It’s a huge ego thing for many people. It’s something that they’ve done well for a long time in their lives and that they’re proud of, and now you’re telling them that they can’t do it anymore.”
Cognitive Testing for Driving Impairment in Dementia
The tests used to measure cognition in Alzheimer disease and other forms of dementia are not useful in determining driving capability, which, as Jitkritsadakul and Bhidayasiri explained in a 2016 review, “is a highly complicated task that is performed in a constantly changing environment and that involves integration of perception, information processing, attention, decision-making, motor programming, executive function, and concurrent task management.”3,4
“If I had 1 or 2 cognitive tests to choose from to try to relate that to driving, it would be the TRAILS B [Trail Making Test Part B] and the Mini-CogTM as short and quick tests,” Dr Chodosh said. “But it’s much more nuanced than that,” he added. “Patients with early Alzheimer disease or related dementias may drive just fine and are no more likely to get into an accident than some others without dementia.”
A practice parameter update by the American Academy of Neurology (AAN)4 found that multiple factors contributed to an ability to assess driving capabilities in a patient with dementia. Only the Clinical Dementia Rating (CDR) scale (Class A) and caregiver’s ratings (Class B) provided better quality of evidence, while a number of other factors were rated Class C.
Tools for evaluation included4:
CDR scale (Level A)
- Caregiver’s rating of a patient’s driving ability as marginal or unsafe (Level B)
- History of traffic citations (Level C)
- History of crashes (Level C)
- Reduced driving mileage (Level C)
- Self-reported situational avoidance (Level C)
- Mini-Mental State Examination (MMSE) scores of ≤24 (Level C)
- Aggressive or impulsive personality characteristics (Level C).
Two factors that were specifically not useful for identifying patients at increased risk for unsafe driving were:
- A patient’s self-rating of safe driving ability (Level A)
- Lack of situational avoidance (Level C)
“The challenge here is that you’ve got an activity that requires a set of complex skills and challenges that may or may not occur at any given moment and a set of possible tasks, none of which are comprehensive enough to really replicate the capabilities required for driving,” which, Dr Chodosh said, points to the need for a proxy of real driving conditions.
Is Road Testing a Better Measure of Driving Ability?
A 2012 study by Ott et al5 assessed real-life driving behavior in 80 older drivers (38 healthy elders and 42 with cognitive impairment) who had passed a standardized road test in Rhode Island. The drivers were video recorded in their own vehicles for 2 weeks, and 4 hours of video were then assessed and rated by a certified driving instructor. The results showed that awareness of signage and traffic behavior—which are likely dependent on higher order executive skills, such as planning and selecting behaviors based on environmental cues—were major factors contributing to driving errors and are not adequately measured in Department of Motor Vehicles (DMV) road tests.
Keeping in lane and lane-changing errors were the most frequent driving mistakes reported in several studies of patients with dementia, according to the Ott study, which concluded that “inaccurate lane positioning and failure to check blind spots while changing lanes are important factors in older drivers that may potentially lead to motor vehicle accidents.” The authors cited that DMV road tests are not conducted in the same driving environments the drivers actually encounter, but in more controlled conditions, which are likely to result in higher quantities of impaired drivers passing the road test. They further concluded that “maintenance of proper lane is an important dimension of driving safety that appears to be relatively underemphasized during the highly supervised procedures of the standardized road test.”
Initiating the Discussion
Neurologists are often relied upon to arbitrate when a patient with dementia should be counseled to stop driving. “I ask people whether they’ve had any accidents, or any recent tickets, or any close calls. And then I will ask permission to ask a family member, ‘would it be okay if ask your wife?” Dr Chodosh explained. He will often recommend that the family member take one or more road trips with the person with dementia in order to ascertain potential areas of impairment.
When a problem does become evident, he tries to put the discussion into a context the patient will appreciate and normalize it, “because as we get older, we all become less able to do some of the things we have always done well. It’s important to paint a picture for someone of the consequences of what could happen if they continue to drive, and would you wish you had made a decision to stop driving if you had known that. No one wants to be responsible for injuring a family member or someone else.”
- Chee JN, Rapoport MJ, Molnar F, et al. Update on the risk of motor vehicle collision or driving impairment with dementia: a collaborative international systematic review and meta-analysis. Am J Geriatr Psychiatry 2017;25(12):1376-1390.
- Vaughan L, Hogan PE, Rapp SR, et al. Driving with mild cognitive impairment or dementia: cognitive test performance and proxy report of daily life function in older women. J Am Geriatr Soc 2015;63(9):1774-1782.
- Jitkritsadakul O, Bhidayasiri R. Physicians’ role in the determination of fitness to drive in patients with Parkinson’s disease: systematic review of the assessment tools and a call for national guidelines. J Clin Mov Disord. 2016;3:14.
- Iverson DJ, Gronseth GS, Reger MA, et al. Practice parameter update: evaluation and management of driving risk in dementia: report of the Quality Standards Subcommittee of the American Academy of Neurology. Neurology. 2010;74(16):1316-1324.
- Ott BR, Papandonatos GD, Davis JD, Barco PP. Naturalistic validation of an on-road driving test of older drivers. Hum Factors. 2012;54(4):663-674.