Neuropsychological driving fitness tests for brain-damaged subjects
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1TNO Human Factors Research Institute, Soesterberg, The Netherlands.
Objectives:
The study was carried out to evaluate and develop simple tools to assess the driving fitness of brain-damaged patients.
Design:
Four neuropsychological tests (predictors) were validated against an open-road driving test (criterion standard), which is used by the Department of Adaptations of the Dutch Driving Licensing Agency for assessing disabled drivers.
Settings:
The predictor tests were conducted in the involved scientific institute; the criterion standard involved participation in normal traffic.
Patients:
The subject group consisted of 33 men and 5 women who had recovered to a stabilized level from traumatic brain injuries. All had valid driving licenses when they were injured and they were considered to be potentially able to recommence driving. The subjects had a mean reported driving experience of 109.200km (SD = 86.300km). All subjects were recovered from a brain trauma with an average coma duration of 33 days (SD = 51 days). They were tested at least 1 year after the accident. All the subjects had normal or corrected-to-normal vision and none used medications that, according to existing medical criteria, interfere with normal psychomotor or cognitive functioning. Ages at the time of the injury were between 17 and 55 years (mean, 29.8; SD, 10.9).
Main Outcome Measures:
Pearson product moment correlations (and explained variances) were calculated between the four predictor tests (a Perceptual Speed test, the WAIS Symbol-Digit Substitution subtest, a Tracking-Reaction dual task, and a Time Estimation task) and the open-road criterion standard.
Results:
The results indicated that performance on both the Perceptual Speed task and the Time Estimation task were significantly correlated with driving performance (p < or = .05). When combined with coma duration and driving experience, the Perceptual Speed and Tracking-Reaction tests together explained 35.3% (r = .59) of the variance in on-road driving performance.
Conclusions:
The amount of variance in open-road driving performance that could be accounted for by these tests was insufficient to completely replace an open-road driving fitness assessment. Also, based on other experimental documentation, it is concluded that more integral, domain-specific test (eg, based on driving simulation) need to be developed.