Effects of alcohol on performance on a distraction task during simulated driving

Abstract

Background: Prior studies report that accidents involving intoxicated drivers are more likely to occur during performance of secondary tasks. We studied this phenomenon, using a dual-task paradigm, involving performance of a visual oddball (VO) task while driving in an alcohol challenge paradigm. Previous functional MRI (fMRI) studies of the VO task have shown activation in the anterior cingulate, hippocampus, and prefrontal cortex. Thus, we predicted dose-dependent decreases in activation of these areas during VO performance.

Methods: Forty healthy social drinkers were administered 3 different doses of alcohol, individually tailored to their gender and weight. Participants performed a VO task while operating a virtual reality driving simulator in a 3T fMRI scanner.

Results: Analysis showed a dose-dependent linear decrease in Blood Oxygen Level Dependent activation during task performance, primarily in hippocampus, anterior cingulate, and dorsolateral prefrontal areas, with the least activation occurring during the high dose. Behavioral analysis showed a dose-dependent linear increase in reaction time, with no effects associated with either correct hits or false alarms. In all dose conditions, driving speed decreased significantly after a VO stimulus. However, at the high dose this decrease was significantly less. Passenger-side line crossings significantly increased at the high dose.

Conclusions: These results suggest that driving impairment during secondary task performance may be associated with alcohol-related effects on the above brain regions, which are involved with attentional processing/decision-making. Drivers with high blood alcohol concentrations may be less able to orient or detect novel or sudden stimuli during driving.

Fig. 1

Photo of “head only” scanner with driving simulator equipment.

Fig. 2

Screen shots of the driving software, with arrow pointing to: 1. standard presentation; 2. no stimulus presentation; 3. oddball presentation.

Fig. 3

Graph of mean response times after oddball stimulus presentation with standard error bars. There is a dose-dependent linear increase (p = 0.018), with the longest response time occurring in the high dose.

Fig. 4

Graph of mean speed before and after oddball occurrence with standard error bars. Speed did not decrease as much in the high dose as it did in the sober and moderate doses. The main effect of alcohol on speed pre and post oddball was significant (p = 0.031).

Fig. 5

Image showing results of repeated measures ANOVA (p < 0.001) for oddball versus standard stimuli for only sober versus high contrast in rendered view (right) and section view (left), showing sub-cortical activation (p < 0.001 uncorrected) in anterior cingulate and hippocampus.

Fig. 6

Contrast plots showing the dose-dependent linear trend of the noted brain activations (BA 19, BA 24) in the targets versus standard comparison.