ALZHEIMER AND VASCULAR DEMENTIAS AND DRIVING - A PROSPECTIVE ROAD ANDLABORATORY STUDY

Objective.-To characterize on-the-road, behind-the-wheel driving abili ties and related laboratory performances of subjects with mild Alzheim er's disease (AD) and vascular dementia. Design.-Prospective, experime ntal study involving two mild dementia and three age and health contro l groups. Road test reliability and validity were assessed. Setting.-G reater western Los Angeles. Subjects were enrolled from the community by referral and from the Veterans Affairs dementia and diabetes clinic s. Participants.-Eighty-seven driving subjects were enrolled; 83 compl eted the study. A sample of eligible dementia clinic subjects consisti ng of 15 mild AD patients met National Institute of Neurological and C ommunicative Disorders and Stroke-Alzheimer's Disease and Related Diso rders Association probable AD criteria, while 12 met Diagnostic and St atistical Manual of Mental Disorders, Revised Third Edition and Hachin ski diagnostic criteria for multi-infarct dementia (vascular dementia) . Clinic control subjects consisted of 15 age-matched patients with di abetes and without a history of stroke or dementia. Community controls consisted of 26 healthy, age-matched, older subjects (>60 years) and 16 young subjects (20 to 35 years). Main Outcome Measures.-Drive score from the Sepulveda (Calif) road test and laboratory measures of atten tion, perception, and memory. Results.-The drive scores in the mild AD group (mean, 22.1; SD, 3.8) and in the vascular dementia group (mean, 24.0; SD, 7.8) differed significantly (P<.001 studentized range test) from the drive scores in the diabetic control group (mean, 31.5; SD, 3.9), the older control group (mean, 32.6; SD, 2.8), and the young con trol group (mean, 33.6; SD, 3.2). Drive score among the three control groups did not vary significantly. Short-term memory (Sternberg), visu al tracking, and Folstein Mini-Mental State Examination scores correla ted best with drive score, with a cumulative R(2) of 0.68. Drive score and number of collisions and moving violations per 1000 miles driven were negatively correlated (r=-0.38; P<.02). Conclusions.-Based on thi s study, type and degree of cognitive impairment are better predictors of driving skills than age or medical diagnosis per se. Specific test ing protocols for drivers with potential cognitive impairment may dete ct unsafe drivers more effectively than using age or medical diagnosis alone as criteria for license restriction or revocation.