Event-level associations between objective and subjective alcohol intoxication and driving after drinking across the college years.

Heavy episodic drinking is strongly associated with driving after drinking, yet there has been mixed evidence regarding whether the disinhibiting effects of alcohol intoxication contribute to the decision to drive after drinking.

This investigation tested whether greater alcohol intoxication increased the probability of driving after drinking particularly during drinking episodes in which students experienced reduced subjective feelings of intoxication. A sample of 1,350 college students completed up to 30 days of web-based daily diary monitoring in each of 4 consecutive years. Participants reported daily on their alcohol consumption, subjective intoxication, and whether they drove after drinking on the previous day or night. 

In generalized estimating equation models, daily estimated blood alcohol concentration (eBAC) was more strongly associated with driving after drinking during episodes in which subjective intoxication was lower. That is, students were most likely to drive after drinking when they were objectively more intoxicated but perceived themselves as less intoxicated.

These event-level associations did not change over time nor did they differ as a function of gender. Further, the effects persisted when predicting driving at eBACs above the legal limit for operating a motor vehicle.

Greater subjective intoxication may serve to inhibit driving after drinking, particularly when students are objectively more intoxicated. In the absence of subjective intoxication, however, other salient pressures might impel driving after drinking. Prevention efforts should incorporate the importance of variability in subjective intoxication.


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