The decision to revoke an older person’s driver’s license has large implications for his or her ability to live independently, yet continued unsafe driving can have adverse consequences for the individual, the family, and others on the road. In addition, in many states there is a legal obligation to assess and identify individuals who may be unsafe behind the wheel.
Patients with mild dementia are at higher risk of accidents while driving than are patients without dementia. However, 76% are still able to pass an on-road driving test (ORDT).
Evaluation
The American Academy of Neurology recently updated its guidelines on the evaluation of driving risk in dementia. Those guidelines recommend assessing the degree of risk for driving according to the following parameters:
Dr. Neil Skolnik and Dr. May S. Lin
• Clinical Dementia Rating (CDR) scale. The CDR is a survey with a scoring system ranging from 0 (normal) to 3 (severe dementia). To assess dementia, the tool measures memory, orientation, judgment, problem solving, community affairs, home and hobbies, and personal care. This rating system has been determined to be a useful predictor. However, it is important to note that 41%-85% of patients with CDR scores indicating mild dementia were found to be safe drivers by an ORDT.
• Mini Mental Status Exam (MMSE). There is conflicting evidence in determining the utility of the MMSE in assessing driver safety. Generally, a MMSE score of 24 or less is useful in predicting an increased risk of unsafe driving in elderly demented patients. However, most studies did not show a correlation between the MMSE score and a driver who is unsafe.
• Patient’s or caregiver’s report. Patients who continue to drive with self-determined restrictions to their driving have a fivefold increase in the risk of crashes. Patients who have mild Alzheimer’s dementia and who rate themselves as safe at driving have a pass rate of only 41% on the ORDT. In fact, in one study, all of the patients with mild dementia who failed the ORDT considered themselves to be safe drivers.
Caregivers can provide useful information, because a marginal or unsafe rating is a useful predictor of risk. Caregivers have a 47% sensitivity and 82% specificity in predicting driver safety, compared with a professional neurologist’s assessment, which has a 61% sensitivity and 91% specificity. What this means is that either a patient’s or a caregiver’s assessment that a patient is not safe to drive is likely to be correct – but an assessment that the patient is safe to drive is often inaccurate.
• History of crashes and/or traffic violations. A history of crashes and/or traffic violations has a strong correlation with unsafe driving in all age groups. A history of crashes within the past 5 years puts a driver at an approximate twofold risk for future accidents, compared with drivers without a history of a crash, which is a higher risk than that for mild dementia alone. A history of traffic violations in the past 2-3 years is also useful in identifying patients with decreased driving ability.
• Reduced driving mileage or self-reported situation avoidance. When patients begin to impose self restrictions or exhibit behaviors of avoidance, it is useful to use this as a sign that they may be unsafe on the road. In one study, patients older than 65 years who reported changing their driving habits because of safety concerns had a fivefold increase in the risk of crashes. This does not mean that patients who do not report being concerned about their driving are cleared from a safety standpoint.
• Aggressive or impulsive personality characteristics. One study reported that agitation and aggression were predictors for demented patients who would refuse to discontinue driving. When patients with dementia deliberately violated driving laws, there was a higher rate of accidents.
• Neuropsychological testing. Currently, there is insufficient evidence regarding the value of neuropsychological testing in helping to assess a patient’s ability to drive.
• Interventions. The next question to ask is whether there are available interventions (such as driver training) that might reduce the risk of accidents in older patients with dementia. Unfortunately, no intervention – including in-person license renewal, licensing restrictions, or driver training – has been shown to reliably decrease the risk of accidents for this group of patients.