Dementia and Driving

As older drivers occupy a larger share of the road,1 the issue has been raised whether these drivers can safely operate a motor vehicle. A variety of age-related physiologic changes and diseases common in the elderly population may compromise driving performance.2 Of these changes and diseases, dementia has generated the most controversy because cardinal features of the disease, memory and judgment impairment, visual-spatial disorders, and inattentiveness, place afflicted persons at risk for unsafe driving. Some have advocated that persons with Alzheimer's disease should be prohibited from driving3 whereas others have argued that a demonstration of impaired driving competence rather than a diagnosis of Alzheimer's disease per se should be the deciding factor.4,5 While debate rages in medical journals, the practicing physician who cares for older patients is likely to be confronted with the situation where he or she discovers that a demented patient is still driving. In many of these cases, the physician is strained between the desire to preserve the patient's independence and the responsibility to preserve the safety of the patient and society. Given this quandary, the answers to a few questions may help focus the current evidence and clarify where the burden of responsibility lies for the decision of whether the demented person can still drive. 1. Do Demented Patients Drive? Although physicians, particularly geriatricians, commonly mention that they are confronted with the situation of an obviously demented patient who is continuing to drive, the prevalence of driving among dementia patients is unknown. Several published reports document a progressive cessation of driving among the demented over several years of follow-up, such that a minority of these patients continue to drive.3,6 However, population-based studies of persons with dementia who are not followed in dementia clinics have not been reported. In a medically frail community-based population of patients receiving Comprehensive Geriatric Assessment at the Southern California Kaiser-Permanente-UCLA Hospitalized Older Persons Evaluation(HOPE) Study, our preliminary data indicate that only 4% of patients with dementia or confusion continue to drive. Thus, the magnitude of the problem in terms of prevalence may have been overestimated. 2. Is the Diagnosis of Dementia Associated with Increased Risk of Motor Vehicle Crashes? The an swer is almost certainly yes, although every published study suffers from either imprecise definition of terms or methodologic limitations that preclude answering the question definitively. Moreover, the magnitude of the risk is unknown and cannot be estimated from the existing literature. Friedland et al3 have reported that 47% of their Alzheimer's disease patients were involved in crashes over a 5-year period compared to 10% of healthy older volunteers, but the number of subjects studied was small. In an uncontrolled study of patients attending a Dementia Research Clinic, caregivers completing a questionnaire reported that 30% of dementia patients had incurred crashes since the onset of dementia (an average of 3.2 years earlier).6 3. Among Demented Drivers, Can Any Clinical Information Discriminate Between Those Who Will and Will Not Have Crashes? In cases of profound dementia, there is usually little question that it is unsafe for the patient to drive. Odenheimer7 has suggested that a close evaluation of attention, visual-spatial function, neglect, and judgment may help identify demented patients who are unsafe for driving. However, in the Friedland et al study, severity of disease as measured by neuropsychological instruments including the Mini-mental State Score did not discriminate between demented drivers who did and did not have crashes.3 In this issue of the Journal, Carr and colleagues8 provide recommendations for Geriatric assessment Centers to use in evaluating and managing demented drivers. Although the report is titled a “consensus statement,” there is no description of a consensus process being used in generating the recommendations. Nevertheless, most of the information in the document is sound advice and good geriatrics practice. Unfortunately, as the authors note, the relationship of information gathered in the history, functional assessment, and mental status examinations to driving capacity is uncertain. The group's recommendations also make good sense empirically but remain untested. The predictive value and misclassification rates of these recommendations are still unknown. As a result, clinicians should be reluctant to adopt them rigidly both for medical and legal reasons. 4. Are Better Tests for Assessing Demented Persons' Driving Ability Being Developed? Realizing that the physician's office or assessment unit are probably not the best places to evaluate driving capacity, a number of new performance-based tests of driving skills have been developed, including Useful Field of View,9 divided attention tasks (J. Fitten, personal communication), and road tests, usually conducted by Occupational therapists.10,11 Some of these have shown promise for eventual implementation as screening methods for the general population of older drivers, and others may be valuable to assess specifically the performance of the demented driver. These tools must, however, be regarded as experimental at present. 5. What Is the Role of the State in Assessment of Driving Capacity? In all states, the privilege of driving is granted by the state. It would, therefore, seem most appropriate for the state to take responsibility for the decision to license demented patients or not. To date, only one state, California, has fully assumed this responsibility. In 1988, Alzheimer's disease and related disorders were added to the list of conditions that physicians are required to report to their local health departments. The guidelines for reporting, modified slightly in 1990, are quite specific, and failure to report may lead to liability for the physician if the patient becomes involved as a driver in a crash. In implementing these statutory regulations, the state has removed the physician from the role of deciding whether a demented patient can drive. This policy has raised concern among some California physicians that, by reporting they are doing a disservice to their demented patients who will invariably lose their licenses. In fact, reporting means only that they will be required to take a reexamination including vision, knowledge, and road tests and have an interview with a Hearing Officer. The physician may also be asked to complete a written driver medical evaluation form. The reexamination process can lead to an unqualified pass, probation, restricted driving, or failure. Failures can be appealed within the Department of Motor Vehicles system and, if necessary, in Superior Court. As a physician who cares for many demented patients, I feel that this process is fair, certainly more equitable than an assessment I could conduct in my office or assessment unit. It does not absolve me of my responsibility to provide advice about driving. Nor does it deter me from optimizing my demented patient's function by treating medical conditions and avoiding medications that might adversely affect driving. Finally, the process does not compromise my role as advocate for my patient's independence. In fact, it is often easier to serve in that advocate role knowing that I do not have to decide whether my patient can drive. The California experience with reporting demented drivers should be noted by other states. The two critical components—mandatory reporting and a fair process of evaluation—must both be present if we are to provide the best possible outcome for our demented patients and society. Given the probable link between dementia and motor vehicle crashes and the tenuous link between current clinical assessment of dementia and crashes, we may best serve both our patients and society by establishing a diagnosis of dementia in patients who meet accepted clinical criteria. In doing so, we have performed a screening function that identifies patients at higher risk for having crashes. Once this information is gathered, it is then the state's responsibility to determine whether the risk is high enough to warrant revoking the driving privilege.