Many College Students Smoke Pot and Drive

Marijuana use was more often associated with driving than alcohol use among young adults

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Parents worry about their kids going off to college and drinking and driving. While this is a real concern, there may be another substance they should be worrying about.

In a recent study, many college-aged kids reported driving after smoking marijuana.

Many of these college-aged kids also admitted to riding in a car when the driver had been smoking marijuana.

"Talk to your kids about the dangers of marijuana and alcohol use when driving."

This research was led by Jennifer H. Whitehill, PhD, of the University of Massachusetts in Amherst.

The investigators interviewed 315 students, aged 18-20 years, by phone the summer before they went to college. The students were asked about their alcohol use, their drug use, and how many times they consumed drugs or alcohol in the 28 days before the interview.

A year later, the same students were asked those questions and others about driving after drinking alcohol or smoking marijuana, and about riding with a driver after the driver had consumed these substances. By that time, the students were enrolled in college. In addition, they were asked questions about how much alcohol they drank and whether or not they wore seat belts when in the car.

In college, the past-28-day prevalence of marijuana use was 29.7 percent for male and 13 percent for female students. When it came to alcohol, 66.7 percent of males and 63.8 percent of females reported using alcohol in the previous month. The prevalence of having used both marijuana and alcohol on the same day was 23.2 percent for male and 8.5 percent for female students.

Of those who used marijuana in the previous month (20.3 percent of the students), 43.9 percent of male and 8.7 percent of female students drove after using marijuana.

When students reported using marijuana, they also often rode with a driver who had used marijuana (51.2 percent of males and 34.8 percent of females).

The majority of students (65.1 percent) drank alcohol, and of these, 12 percent of males and 2.7 percent of females drove after drinking, and 20.7 percent of males and 11.5 percent of females rode with a driver who’d been drinking.

Those who drove after drinking or using marijuana were twice as likely to ride in a car with someone who had used alcohol or drugs.

Among students who used substances, marijuana users had a higher prevalence of driving and riding after marijuana use than alcohol users had for driving or riding after alcohol use.

The study authors noted that other studies have shown that driving after marijuana use is perceived as safer than driving after alcohol use and done more frequently. This study seems to suggest the same. The authors noted that the mistaken assumption that it is safer to drive under the influence of marijuana than alcohol is a concern, as through legislation, marijuana may become more available than it has been in the past.

The investigators noted numerous limitations to this study, including that they did not assess the time between substance abuse and driving, and that drinking and smoking marijuana were self-reported.

They pointed out how important this study is in stressing that young adults need to be made aware that driving after using marijuana is dangerous. In fact, these researchers stated that statistics show that nationally, cannabis use is involved in 12 percent of fatal crashes among 16- to 20-year-olds.

Cliff Hamrick, LPC, a counselor in Austin, Texas, told dailyRx News that he thinks it's easy for people to forget that marijuana is a powerful drug.

"While I agree with efforts to decriminalize marijuana usage, I believe it is important to remember that marijuana is a drug that can have an effect on one's cognitive, emotional, and behavioral functions," Hamrick said.

"Often, it feels like those who support the decriminalization of marijuana want to swing the pendulum in the opposite direction and pretend that marijuana is a completely harmless drug. As marijuana use becomes more mainstream in society, mental health professionals will need to educate our clients that marijuana is as potent and dangerous drug as alcohol or prescription pills," he said.

In an accompanying editorial, Mark Asbridge, PhD, of Dalhousie University in Halifax, Nova Scotia, Canada, mentioned that it is even possible that marijuana and alcohol, when taken together, may cause more impairment because of a synergistic effect (the effect may be greater than simply adding the two together).

But he ended on a positive note. “As we learned from our multipronged efforts to combat drinking and driving, it took many years before the desired effects of legislation were realized. By focusing energy on the problem of driving after marijuana use and drawing on our successes and failures in responding to drinking and driving, we may not have to wait as long this time to realize change," Dr. Asbridge wrote.

This study appeared online May 12 in JAMA Pediatrics.

The study authors disclosed no conflicts of interest.

Review Date: 
May 12, 2014
Last Updated:
May 13, 2014