Chronic Marijuana Use in Male Teens Not Linked to Later Issues

A marijuana vendor prepares samples for enthusiasts gathered at the "Weed the People" event to celebrate the legalization of the recreational use of marijuana in Portland, Oregon. A new study has found that chronic marijuana use in teens does not lead to later symptoms like depression. Steve Dipaola/REUTERS

Researchers from the University of Pittsburgh and Rutgers University have found that frequent marijuana use by teenage boys does not correlate to later physical and mental health issues. The results of the new study, published by the American Psychological Association in the journal Psychology of Addictive Behaviors, contradicted prior data on marijuana use, and surprised lead researcher Jordan Bechtold of the University of Pittsburgh Medical Center.

"There were no differences in any of the mental or physical health outcomes that we measured regardless of the amount or frequency of marijuana used during adolescence," Bechtold said in a press release.

Bechtold was expecting to find a link between teen marijuana use and a variety of later symptoms. But the study found that both physical ailments (such as cancer, asthma and respiratory problems) and mental ailments (such as lifetime depression and anxiety), were equally likely for non-marijuana users and frequent smokers. The study, which was designed to see if ethnicity could be a factor in later health problems, also found no increased risk for young black men, who comprised 54 percent of the tracked population, as compared to the general population.

The study collected data on 408 males, following them from their teenage years to their mid 30s, the release said. It is one of several studies that has tracked marijuana use in subjects over decades of their lives. Participants were grouped into four categories based on their frequency of use. Forty-six percent of the subjects were "low or non" users, while the remaining 54 percent consisted of chronic users who began smoking at different times during their adolescence. The study also controlled for other factors linked to health problems, such as cigarette smoking and lack of health insurance. However, as the study's conclusion notes, the data were all self-reported. Men who did not visit the doctor frequently could have failed to identify their own symptoms.

"One study should not be taken in isolation," Bechtold said in the release. The study's conclusion suggests a number of different avenues for future research, such as examining the effects of different marijuana potencies and amounts. It also noted that the average THC levels in marijuana confiscated by the U.S. government has increased since the 1990s and early 2000s, when the study's data was collected.

Bechtold's hesitancy to draw a blanket conclusion comes from his knowledge of prior long-term marijuana research, but the study underscores that marijuana policy is not a black-and-white issue. "The health outcomes associated with marijuana use are just one piece of the legalization puzzle," the study says. Health risks have to be balanced against other effects—and the potential benefit—of smoking marijuana.