Mrs. Smith, your 85-year-old patient, was recently discharged from an inpatient psychiatric unit for depression. She shares that her psychiatrist recommended she stop driving because she didn’t do well on “some cognitive test” (she scored 22/30 on the Montreal Cognitive Assessment (MoCA)). Although her son expresses concern about a few fender benders recently, Mrs. Smith insists she’s perfectly safe to drive. 

It’s often hard to draw the line between safe and unsafe driving. Although drivers between the ages of 60–79 years have the lowest crash rate of any demographic, this drastically changes later in life. Drivers older than 80 years have the second highest crash rate and the highest crash fatality rate (www.tinyurl.com/49h2jsv9). Waiting for a “close call” to convince your patients that their driving is no longer safe is a dangerous option. A helpful alternative is to think through a patient’s risk factors for accidents, including their underlying health issues, medication use, and cognitive performance. 

Contributors to driving performance

Patients with the following diseases may require more frequent evaluation of their driving ability:

Dementias

In preclinical Alzheimer’s disease (AD), patients may already experience deficiencies with eye tracking (Carr DB and Grover P, Geriatrics 2020;5(2):36). As the disease progresses, patients can experience difficulties with visual searching (ie, scanning the environment for a particular object, such as a traffic sign, among other similar objects), thereby increasing their risk of a car accident (Carr and Grover, 2020). They may also lose their sense of direction, preferring to stick with familiar, local routes.

Patients with frontotemporal dementia may experience impaired judgment and increased impulsivity, which can lead to road rage, limited insight, and car accidents (Falkenstein M et al, Geriatrics (Basel) 2020;5(4):80). Early executive impairment impair, especially in complex driving situations.

Patients with Lewy body dementia and Parkinson’s disease dementia may experience difficulty physically operating a vehicle. For example, stiffness can lead to difficulty with turning their head, and hand tremors may cause them to drop objects. They may also experience visuospatial impairment.

Patients with vascular dementia may experience executive dysfunction, trouble paying attention, and episodes of confusion.

Other diseases and risk factors

• Sleep apnea and other sleep-related disorders can impair a patient’s ability to focus. 
• Pain can also impair focus and limit movement. 
• Depression and anxiety are associated with an increased crash risk (Hill LL et al, Inj Epidemiol 2017;4(1):10). Common medications used to treat these disorders may also cause dizziness and sedation, impairing a patient’s driving ability. 
• Numerous medications can affect driving by causing sedation, blurred vision, slowed reaction times, or attentional problems. Look out for opioids, muscle relaxants, sedatives, antiepileptic medications, and ­antihistamines.
• Sensory impairment, including vision and hearing problems, can make it difficult for patients to notice warning signs and to interpret traffic and road conditions.

Assessment

Asking your patients about their driving often provides little valuable insight. In one study, over 85% of patients rated themselves as “good” or “excellent” drivers regardless of their driving record (Ross LA et al, Accid Anal Prev 2012;48:523–527). Interestingly, physicians are likely to overestimateof patients with a high number of traffic violations, which is an important limitation in their fitness-to-drive recommendations (Ranchet M et al, Gerontologist 2017;57(5):833–837). For these reasons, we advocate for a more standardized approach.

We generally recommend assessing a patient’s attention, visuospatial, and executive functioning, such as by screening with the MoCA or Mini-Mental State Exam. The trail-making test of the MoCA is an excellent predictor of motor vehicle collision risk (Falkenstein et al, 2020). Failure in your patient’s ability to draw a clock can also identify deficits in executive functioning. Keep in mind that screening tests alone cannot determine safe driving. Patients with mild cognitive impairment can still drive safely as their procedural memory may be relatively well preserved. 

In addition to screening cognition, we ask patients and their caregivers about: 

• Recent accidents or “near misses” 
• Whether there are new unexplained dents and scratches on the patient’s car
• Whether the patient experiences increased anxiety around driving
• Whether the patient has gotten lost while driving

We then evaluate the patient’s medications and consider whether their medical comorbidities could impact their ability to drive safely. 

A behind-the-wheel driving test is the gold standard for assessing driving safety. If a patient fails a screening test, it’s best to refer them for a driving test. Clinicians can recommend testing through driver rehabilitation programs or through the Department of Motor Vehicles (DMV). A third-party opinion also helps back up a clinician’s recommendation to stop driving, minimizing the harm to the patient-doctor relationship. In a meta-analysis comparing patients with AD against healthy controls, 33% of patients with mild dementia failed an on-road driving test compared to only 1.6% in the control group (Falkenstein et al, 2020). Unfortunately, the loss of driving rights can result in worsening physical and cognitive abilities and a doubling of the risk of depression (Chihuri S et al, J Am Geriatr Soc 2016;64(2):332–341). Knowing this risk, clinicians can proactively work with patients to brainstorm behavioral changes—whether it’s adding a hobby to their schedule, joining a support group, or increasing their physical activity. 

Interventions

Almost two-thirds of US states include laws that impart special rules on drivers based on their age. Many states—but not all—encourage or allow clinicians to report patients with driving impairments to the Registered Motor Vehicle Division. Currently, only six states (California, Delaware, Nevada, New Jersey, Oregon, and Pennsylvania) mandate reporting of patients who are cognitively or medically impaired. 

Clinicians are often hesitant to suggest their patients refrain from driving due to fears that their alliance is at risk. If you are concerned, first consider whether their medications and treatment of their medical comorbidities are optimized. You can suggest that the patient avoid higher-risk routes, like complex intersections with difficult left turns (Mayhew DR et al, Traffic Inj Prev 2006;7(2):117–124). You can also encourage your patient to register for a driver retraining program, such as through the National Safety Council, although this may be cost-prohibitive. Ultimately, however, it is our duty to protect public safety. If the patient does not have potential to rehabilitate, you may need to report them to the DMV.

You recommend Mrs. Smith refrain from driving until she completes a behind-the-wheel driving test. She eventually loses her license after failing this test. At her follow-up appointment, she reports that she now relies heavily on family members for transportation. She also expresses feeling deeply unhappy due to her loss of autonomy. You provide a list of driving services in the area and ask if she wishes to consult with a social worker to discuss additional transportation options.

CARLAT VERDICT

When evaluating driving safety, cognitive screening can be helpful. However, the gold standard remains a behind- the-wheel driving test. Look out for social isolation and depressive symptoms when patients stop driving.