The effects of Alzheimer disease on driving-related abilities.

Ten Alzheimer disease (AD) patients and 12 healthy elderly controls were evaluated on two tests of driving-related abilities: the Driver Performance Test (DPT) and the Driving Advisement System (DAS). Subjects were administered a battery of neuropsychological tests to determine if severity of dementia in AD correlates with driving performance. On the DPT, the AD patients scored in the average range in two of five skill areas (predicting the effects of a hazard, deciding how to avoid it); below average in two areas (searching for a hazard, executing evasive actions); and poorly in one area (identifying hazards). The elderly controls scored at an average level in all five skill areas. On the DAS, AD patients were significantly slower than the elderly controls on simple, two-choice, and conditional reaction time tests and were much slower than drivers in general. The AD patients' performances on two cognitive tests, the Mini-Mental State Examination (MMSE) and the Category Fluency Test, correlated significantly with aspects of performance on the DPT and the DAS. Although these are preliminary results from a pilot investigation, they suggest that AD patients' driving-related abilities are adversely affected by the disease and that driving-related performance tests and neuropsychological tests may be useful in assessing the impact of AD on driving.