Simulated driving performance in young drivers with concussion

Statement of Purpose

Concussion is common among young drivers. In 2015, an estimated 470,000 people between 16–25 years of age sustained a concussion requiring medical treatment. Concussion impairs cognitive processing speed, attention, concentration and integration – skills which are also important for safe driving. We examined whether concussion negatively impacts simulated driving performance among young drivers, relative to control drivers without concussion.

Methods/Approach

This was a case control study. Participants were male and female licensed drivers between 16–25 years of age. Participants with recent concussion were recruited from clinical sites within two weeks of concussion diagnosis. Control participants were recruited from community sites. Measures: Baseline simulated driving performance was measured in a simulator at the University of Washington. Researchers defined controlled variables, including road configuration, traffic, and environment. Data output includes speed, acceleration, braking, lane position, and steering wheel movement. Following a familiarization task, simulator tasks involved an urban driving scenario with response to unexpected driving events, and a rural scenario with cognitive tasks. A validated method in testing cognitive load during simulated driving is the tactile detection response task (TDRT). Each participant was asked to press a button in response to a tactile vibration stimulus. Performance was measured by response times and miss rates. Driving performance was re-evaluated one month after the baseline measurements.

Results

We used fixed effects Poisson regression models to examine concussion status in relation to TDRT miss counts. We used fixed effects linear regression models to examine concussion status in relation to TDRT reaction time. Multivariable models controlled for age, sex and driving experience.

Results

We studied simulated driving performance among 17 concussed young drivers and 29 controls. In simulated driving performance, young drivers with concussion had 26% slower reaction times in responding to a tactile cue while driving at baseline (963ms vs. 767ms), with modest improvement after 1 month – 16% slower reaction time (800ms vs 687ms). Concussed drivers were twice as likely to completely miss a response to a tactile cue at baseline compared with control drivers (8 vs. 4.5 misses), with improvement by 1 month (3.7 vs. 3.5 misses).

Conclusion

At baseline, drivers with concussion scored significantly worse on measures of reaction time and cognitive function during simulated driving, measure relative to healthy controls. Performance among concussed patients improved at follow-up, though remained below performance for control drivers.

Significance

Concussion is likely to impair cognitive function important to safe driving; our study suggests several tests which could guide clinician evaluation and evidence-based counseling following mild traumatic brain injury.