Crashes and violations among drivers with Alzheimer disease

Background: Several small studies have found a high automobile crash rate for drivers with Alzheimer disease (AD) compared with unaffected elderly drivers, prompting the suggestion that the diagnosis of AD mandate cessation of driving. Objectives: To compare automobile crash and violation rates of a large number of patients with AD with appropriately matched elderly subjects. To determine if neuropsychological test scores predict these adverse driving events. To determine if intervention by physicians or family members influences driving cessation. Design: Review of crashes and violations from 1986 to 1993 in police-filed Michigan State driving records of 143 licensed patients with AD and 715 licensed comparison subjects matched 5 to 1 in age (+/-6 years), sex, and county of residence. We correlated crashes and violations with neuropsychological test scores. A questionnaire-based inquiry on the influence of physician, family, and state interventions on driving cessation was administered. Results: The crash and violation rates of patients with AD were not significantly different from those of comparison subjects. However, patients with AD probably drove fewer kilometers than did comparison subjects. Neuropsychological test scores did not predict future crashes or violations. Conclusions: This study, the largest to our knowledge involving state driving records of patients with AD, does not confirm the previously reported excessive crash rate among drivers with AD relative to an appropriate comparison population. Reduced driving exposure of patients with AD probably kept their crash adverse equal to that of comparison subjects. Intervention by physicians and family members was a major factor in reducing driving exposure. These findings affirm that the mere diagnosis of AD does not justify license revocation.