To compare detriments to driving ability related to Alzheimer's disease (AD) and normal ageing, 19 patients with AD and 48 apparently normal elderly subjects were assessed on measures of cognitive ability to drive (Stroke Drivers Screening Assessment SDSA). The presence of AD could have a large detrimental effect on driving ability, as measured by a battery of cognitive tests known to be related to on-road driving performance. All of the AD group failed, whereas 48% of the control group failed (mean = 5.09, 95% confidence interval 3.75-6.43; t = 7.59. df = 65, p > 0.001). Normal ageing may also have a detrimental effect on driving ability, as a significant negative correlation was found between apparantly normal ageing and performance on the battery (r = -0.72, 95% confidence interval -0.6 to -0.8; df = 56, p > 0.001). These data suggest that cognitive decline related to AD and normal ageing may render some unsafe to drive, provided that the correlation between the SDSA and on-road driving skills holds for normal and demented elderly. Further validation of the SDSA is needed but cognitive screening may well be an important tool in deciding about an individual's safety on the road.
Abstract