Alzheimer's disease and driving: prediction and assessment of driving performance.

OBJECTIVES To examine driving competence in a group of drivers diagnosed with probable Alzheimer's Disease (AD) in terms of a standardized open road evaluation and expert judgments. To examine the validity of a standardized medical examination, including administration of the Mini-Mental Status Exam (MMSE), and a standardized neuropsychological assessment as predictors of open road driving performance. DESIGN A prospective investigation with consecutively referred subjects. SETTING Coorabel Driver Assessment Centre, Royal Rehabilitation Centre Sydney, Australia. PARTICIPANTS Nineteen subjects with a diagnosis of probable AD. MEASUREMENTS A standardized clinical medical examination, a standardized neuropsychological assessment, and a standardized open road driving evaluation. The driving evaluation provided a correct driving actions score. The outcome measure was the expert judges' rating of overall driving competence, which was termed the final on-road result. RESULTS Seven subjects passed the on-road driving evaluation, and 12 failed. MMSE was found to be a significant predictor of final on-road result. The physician's prediction, the neuropsychology test scores, and the neuropsychologist's prediction were not found to be significantly associated with the final on-road result. The on-road driving evaluation was a reliable test. CONCLUSION Inasmuch as all subjects except one were still driving and all wished to continue to drive, it is important to note that 63.2% of subjects failed the on-road evaluation. Conversely, 36.8% were judged safe to drive, suggesting that AD diagnosis alone may be insufficient criteria for cessation of driving. A standardized road test may be the only appropriate means of determining driving competence in people diagnosed with AD.