Driver route-following and safety errors in early Alzheimer disease.
OBJECTIVE
To assess navigation and safety errors during a route-following task in drivers with Alzheimer disease (AD).


METHODS
Thirty-two subjects with probable AD (by National Institute of Neurological and Communicative Disorders criteria) of mild severity and 136 neurologically normal older adults were tested on a battery of visual and cognitive tests of abilities that are critical to safe automobile driving. Each driver also performed a route-finding task administered on the road in an instrumented vehicle. Main outcome variables were number of 1) incorrect turns; 2) times lost; and 3) at-fault safety errors.


RESULTS
The drivers with mild AD made significantly more incorrect turns, got lost more often, and made more at-fault safety errors than control subjects, although their basic vehicular control abilities were normal. The navigational and safety errors were predicted using scores on standardized tests sensitive to visual and cognitive decline in early AD.


CONCLUSIONS
Drivers with Alzheimer disease made more errors than neurologically normal drivers on a route-following task that placed demands on driver memory, attention, and perception. The demands of following route directions probably increased the cognitive load during driving, which might explain the higher number of safety errors.
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Division of Neuroergonomics, Department of Neurology, College of Medicine, University of Iowa, Iowa City, IA, USA.
Rizzo
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Anderson
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Shi
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Dawson
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JD
D000368:Aged; D000544:Alzheimer Disease / Q000523:psychology*; D001334:Automobile Driving / Q000523:psychology* / Q000592:standards; D005260:Female; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000453:epidemiology* / Q000209:etiology; D011939:Mental Recall; D008875:Middle Aged; D009483:Neuropsychological Tests; D011596:Psychomotor Disorders / Q000453:epidemiology* / Q000209:etiology; D012449:Safety; D012720:Severity of Illness Index; D013037:Spatial Behavior; D014787:Vision Tests