Researchers from the University of Bristol in Britain have found that both regular and occasional marijuana use as a teenager is associated with a greater risk of other illicit drug taking in early adulthood.
The study by Bristol's Population Health Science Institute also found cannabis use was associated with harmful drinking and smoking. The researchers looked at marijuana use among more than 5,000 British teenagers aged 13–18. One in five used cannabis.
Unlike in the US, cannabis is often smoked with tobacco in the United Kingdom. The study found that UK teens who regularly used cannabis were 37 times more likely to be nicotine dependent and three times more likely to have a harmful drinking pattern than non-users by the time they were 21. Even more troubling, they were 26 times more likely to use other illicit drugs.
Cannabis is illegal to possess, grow, distribute or sell in the United Kingdom. In the US, it remains an illegal substance under federal law but 64 percent of Americans now live in states that permit the medical use of marijuana for a variety of conditions, including epilepsy, Parkinson's disease, multiple sclerosis and posttraumatic stress disorder. Eight states and the District of Columbia have fully legalized marijuana for recreational use for adults who are 21 years of age and older. One of those states is Oregon where voters approved legalization in 2014 and the law took effect in 2015.
Binge drinking with easy access to marijuana is a recipe for disaster. Students at the Oregon university who reported binge drinking were 73 percent more likely to also report marijuana use compared to peers at schools in states where marijuana remains illegal. "Those who binge drink may be more open to marijuana use if it is easy to access, whereas those who avoid alcohol for cultural or lifestyle reasons might avoid marijuana regardless of its legal status," said the study's lead author David Kerr, an associate professor in the School of Psychological Science in OSU's College of Liberal Arts.
The researchers also found that Oregon students under age 21—the minimum legal age for purchasing and using marijuana—showed higher rates of marijuana use than those over 21.
"This was a big surprise to us, because legalization of use is actually having an impact on illegal use," said Harold Bae, the study's primary statistician.
"Americans are conducting a big experiment with marijuana," Kerr said. The outcome of that experiment might be even more addiction in the United States.