DRIVING PERFORMANCE IN PERSONS WITH MILD SENILE DEMENTIA OF THE ALZHEIMER-TYPE

Objective: To assess the effect of mild senile dementia of the Alzheimer type (SDAT) on driving ability. Design: Cross-sectional study with correlation analysis. Setting: A university-based Alzheimer's Disease Research Center, which evaluates community-living older adult volunteers, and the university's Program in Occupational Therapy. Participants: Healthy elderly controls (n = 13) and subjects with very mild (n = 12) and mild (n = 13) SDAT. Dementia severity was staged by the Washington University Clinical Dementia Rating. Measurements: The driving ability of participants on the in-car road test was scored independently by a driving instructor, blinded to the study design and to the dementia status of the subjects, and an unblinded occupational therapist. Interview-based perceptions of driving ability were obtained independently from the subjects and their collateral sources. Attentional and visuospatial performances of the subjects were assessed prior to the road test. Results: All control and very mild SDAT subjects were judged to be ''safe'' drivers (ie, passed the in-car road test), but five (40%) of the mild SDAT subjects had driving impairment sufficient to ''fail'' the road test. Neither subject self-assessment nor caregiver perceptions of driving ability consistently predicted driving performance. Attentional task performance correlated well with road test results. Conclusions: Some SDAT subjects retain ''safe'' driving skills. The greater the dementia severity, the greater the likelihood of poor driving ability. Performance-based (road test) evaluations are necessary to properly determine driving skills at present, but attention and other cognitive screening measures should be developed.