The criteria that can be applied to determine if driving is safe in patients with early Alzheimer's disease (AD) are unknown. Self-monitoring and correction of driving errors are required for normal driving. It is well established that patients with advanced AD are more likely to get lost because of deterioration in topographic, verbal, and spatial memory. Uc et al (2004) analyzed the occurrence of driving errors in patients with mild AD who were given verbal driving instructions.
The experimental paradigm assessed control of speed, lane position, unplanned lane deviations, times lost, and incorrect turns among patients and age-matched controls. The proportion of subjects who made incorrect turns, lost their way, or made safety errors was much higher in the AD group than in the control group. These differences persisted when adjusted for familiarity with the neighborhood, far visual acuity, and near visual acuity.
The tendency for AD patients to get lost or become disoriented in unfamiliar surroundings may have specific implications for driving. The authors hypothesize that compromised visuospatial ability or cognitive overload associated with performing a route-following task among patients with early AD might account for the increased number of safety errors observed. Assessing the safety of driving for patients with early AD might include tests of vision, perception, memory, and attention. The accompanying editorial (Drachman, 2004) recommends that a family member ride with such a patient at least once a month; if the observer feels in danger, the driver should no longer operate a vehicle. Better criteria clearly are needed to define acceptable driver safety among patients with cognitive impairment, including patients with early AD.
Drachman DA: Safe driving: Aging and Alzheimer disease. Neurology 63:765, 2004
Uc EY et al: Driver route-following and safety errors in early Alzheimer disease.