Approximately 22 million older adults (78%) have valid drivers' licenses, and the number will grow until 2029 as the baby boomer generation ages.1 This dramatic change in demographics will be reflected in the driving population, so there will be a greater need for cost-effective and valid methods for identifying at-risk older drivers.2
A variety of age-related medical and cognitive conditions affect driving fitness. There is a great deal of heterogeneity in how people age as well as in the time course of age-related decline. Inevitably, changes in cognitive and perceptual abilities occur that are directly relevant to driving. Increased age is associated with diminished visual and auditory perception, with decreased visual fields, poor visual acuity, decreased glare resistance, and hearing loss.
Normal aging does not affect all cognitive processes required for driving, but in many older adults, vigilance and the ability to multitask are affected and reaction time and processing speed are slowed.3,4 Given the physical changes that occur with age, it is not surprising that there are considerably higher crash rates for older drivers. Drivers older than 85 have more motor vehicle accidents than new drivers younger than 19. The Insurance Institute for Highway Safety reports that fatal crash rates per mile driven are higher for drivers older than 80 than for any other age-group except teenagers.5
The relationship between increased age and driving is further complicated by the increased incidence of dementia in older adults. The prevalence of dementia in Americans older than 71 is nearly 14%, and the prevalence increases to 37% in persons 90 or older.6
Patients with Parkinson disease (PD) and Alzheimer disease (AD) are susceptible to impaired driving, and their driving skills are further compromised by problems with route-finding or navigation.4,7,8 Some patients with early, mild dementia retain safe driving skills but their risk of getting lost because of memory and visuospatial deficits may be increased.9,10 Patients with early AD have up to 7 times the crash risk of drivers without AD.11 Patients with PD often have fluctuations in attention, alertness, and motor functions because of the disease and also because of the adverse effects of medications.
Although the functional impairment in patients with dementia may wax and wane, in general, drivers are slower, make more errors at intersections, are less aware of other drivers, have less lane control, and engage in more frequent and unexpected braking.12 Despite memory loss and other cognitive problems, procedural memory (ie, skill-based knowledge) is often preserved with dementia. This means that many individuals with dementia retain the mechanical and procedural skills needed to drive. Paradoxically, the relative preservation of skill-based memory poses a problem for individuals with dementia who may lack awareness of their cognitive and perceptual limitations and who may insist on driving.
Office-based driving tests sample multiple domains—such as processing speed, visual attention, and executive function—using predictive tests, including the Trail Making Test, Useful Field of View test, and Mini-Mental Status Exam. However, office-based predictive tests are not an adequate substitute for a road test, which is the gold standard of driving assessment..
This article reviews the data on factors that affect driving ability and the utility of available predictive tests. Recommendations for encouraging at-risk drivers to stop driving and for easing the transition to driving cessation are included.
Recommendations for driving screening measures, factors to consider in driving cessation, and recommendations for approaching driving cessation with a patient and family have immediate relevancy in daily psychiatric practice.
Regulatory policies and medical recommendations
Physicians are often asked to make judgments regarding an older person's ability to drive, and psychiatrists may be called in for consultation. Many physicians look to professional organizations for guidelines on driving, but such guidelines are variable. The American Academy of Neurology (AAN) recommends that caregiver ratings of a patient's driving ability, history of crashes or citations, reduced driving mileage, and severity of dementia be used as predictors of driving competence. The AAN discourages the use of a patient's self-report of driving ability.13 The AAN also promulgates guidelines regarding the relationship between severity of dementia and driving fitness. It recommends that driving cessation be encouraged for patients with a Clinical Dementia Rating Scale of 1, which indicates mild symptoms of dementia but along with other factors translates to moderate risk.13
Ethical guidelines from the AMA prioritize driving safety over patient confidentiality; they encourage physicians to notify their state's Department of Motor Vehicles (DMV) when they suspect that a patient is unsafe to drive, and they defer to state medical societies. The AMA emphasizes the need for protections regarding physician liability for reporting unsafe drivers. Continuing education courses sponsored by the AMA have helped clinicians adopt in-office screening to assess and document driver safety.14
Drivers are expected to disclose relevant medical conditions (eg, dementia, epilepsy, PD) to their state's DMV. Six states (California, Delaware, Oregon, Nevada, New Jersey, and Pennsylvania) have issued laws that require physicians to report persons with neurological disabilities that might impair driving; California and Oregon require physicians to report patients with dementia.15 However, most states give physicians the discretion to choose whether to report a driver whose condition requires consideration by the DMV.
The legal determination of the inability to safely drive is made by the DMV. Medical qualifications for operators of motor vehicles vary across states, and there is no national legal standard for the identification of an at-risk driver. Across the US, regulations vary with respect to license renewal policies, the age at which one is considered old, and whether physicians are mandated reporters of individuals with dementia. Physicians who observe laws in good faith have full legal immunity in most states; however, in some states (eg, Arkansas, Georgia), physicians risk lawsuits for reporting a patient with questionable driving abilities because it breaches patient-physician privilege. In still other states (eg, Michigan, Montana), physicians can be held liable if a patient who is deemed to be “sound” based on medical standards later has an at-fault accident. The AAA Foundation for Traffic Safety Web site maintains a listing of each state's requirements for unsafe drivers.16
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