Teen marijuana use not linked to later depression, lung cancer, other health problems, study finds

Chronic marijuana use by teenage boys does not appear to be linked to later physical or mental health issues such as depression, psychotic symptoms or asthma, according to a study published by the American Psychological Association.

Researchers from the University of Pittsburgh Medical Center and Rutgers University tracked 408 males from adolescence into their mid-30s for the study, which was published in Psychology of Addictive Behaviors.

"What we found was a little surprising," said lead researcher Jordan Bechtold, PhD, a psychology research fellow at 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."

Marijuana use has undergone intense scrutiny as several states and the District of Columbia have legalized the drug, prompting the researchers to examine whether teen marijuana use has long-term health consequences. Based on some prior studies, they expected to find a link between teen marijuana use and the later development of psychotic symptoms (delusions, hallucinations, etc.), cancer, asthma or respiratory problems, but they found none. The study also found no link between teen marijuana use and lifetime depression, anxiety, allergies, headaches or high blood pressure. This study is one of just a few studies on the long-term health effects of teen marijuana use that have tracked hundreds of participants for more than two decades of their lives, Bechtold said.

As laws prohibiting marijuana become less punitive, the question, “What about the kids?” becomes more pressing to parents and other adults.

We at the Drug Policy Alliance urge young people to abstain from alcohol, tobacco, and other drugs. We avoid the exaggerations, misinformation and scare tactics of the past. We believe that honesty is the best way to engage youth and the most empowering way to help them make responsible, informed decisions.

Some critics of drug policy reform exploit parents’ worries that legal access to marijuana for adults will make young people more likely to use it. They proclaim that these reforms send the wrong message to kids. They also threaten that adjusting our response to youthful experimentation will inevitably lead teenagers down a path of problematic use and toward more dangerous drugs.

The research was an offshoot of the Pittsburgh Youth Study, which began tracking 14-year-old male Pittsburgh public school students in the late 1980s to analyze various health and social issues. For 12 years, participants were surveyed annually or semiannually, and a follow-up survey was conducted with 408 participants in 2009-10 when they were 36 years old. The study sample was 54 percent black, 42 percent white and 4 percent other races or ethnicities. There were no differences in the findings based on race or ethnicity.