ABSTRACT
The Problem. Learning how to drive, and drive safely, is a very complex process and one on which the lives of new drivers and others can depend. For young, new, and novice drivers, the process of learning how to drive can also occur at the same time that they are learning about the use of alcohol or other drugs like cannabis. The combination of novice driving and experimentation with alcohol and others drugs may be particularly hazardous. For example, the impact of a given amount of alcohol, including low doses, on the collision risk of young drivers is substantially greater than its impact on older drivers. Epidemiology of Driving after Drinking and Driving after Using Cannabis. For many years, researchers have examined the occurrence of driving under the influence of alcohol (DUIA), and research suggests that rates of DUIA have declined recently. Rates of driving under the influence of cannabis (DUIC) have received attention only more recently, and existing research suggests that among young drivers, rates of DUIC may equal or exceed rates of DUIA. Effects of DUIA and DUIC on Driving Skills. Many studies have assessed how alcohol affects driving skills. Results of studies examining the effects of alcohol on the performance of laboratory tasks involving psychomotor and cognitive skills, simulated and natural driving, and risk of collision among drivers converge to clearly demonstrate that DUIA impairs driving skills and increases collision risk. This effect appears to be exponential as the amount of alcohol consumed increases. Evidence on the effects of cannabis, on the other hand, is much less and has been more controversial. While some early studies suggested that DUIC did not increase collision risk, more recent evidence now indicates that it does. Prevention Efforts. Much effort has been directed to preventing DUIA among the general driving population and among young drivers, including educational, legal, and enforcement initiatives. Much is known about the effectiveness of DUIA prevention efforts, including their ability to reduce collision-related casualties, although more work to understand these effects among young and new drivers specifically is needed. On the other hand, efforts to prevent DUIC are in their infancy, and little evidence on their impact is available.
