"The association between adolescent cannabis use and anxiety," a study in the March 2018 Addictive Behaviors journal, highlights the difficulties with cannabis-harm studies while offering a credible solution for reducing anxiety and teen cannabis use. The study involved 250 adolescents, mostly of Hispanic descent, between the ages of 14 and 17. The researchers assessed the subjects' mental health and cannabis, alcohol and cigarettes use and then followed up at the six-month and one-year marks. What did they find?
"Our results suggest that, during adolescence, early cannabis use has a greater influence on prospective reports of anxiety, than vice versa," the researchers concluded. "Specifically, adolescents exhibiting higher initial levels of cannabis use displayed more persisting self-reported anxiety across time, as compared to those with less frequent use."
The data might well be correct, but it highlights the longstanding problem with studies that attempt to differentiate between correlation and causation using self-reported information. As the researchers would likely agree, a self-reported increase in anxiety over a year doesn't prove cannabis biologically caused it.
Consider the many caveats. First, the participants all had previous exposure to cannabis, alcohol and/or cigarettes, and it's not unreasonable to assume a joint-toking, beer-drinking 14-year-old might have co-occurring issues like trauma or mental health predispositions. Likewise, individuals with anxiety disorders often self-medicate their moods with cannabis. While the study said early levels of anxiety did not influence "rates of change in cannabis use," previous exposure to cannabis limits one's ability to assess reasons for initial use, which possibly involved self-medicating emerging symptoms.
Other factors could also contribute to increased anxiety. For example, smoking cannabis in the age of prohibition can involve anxiety-increasing stress, including the fear of criminal arrest, family conflict, school eviction and partaking in black market sales. These fears can also keep adolescents from seeking informed advice on proper use, and overconsumption can contribute to acute (i.e., short-term) bouts of anxiety (as opposed to chronic, long-term anxiety). Moreover, the participants were mostly of Hispanic descent, and a growing grasp of modern racial issues (e.g., sanctuary cities, deportation, "build the wall") can negatively affect self-image and mood regardless of legal status. These environmental factors have the potential to skew the data, which is why correlation is not a strong argument for biological causation.
The study did, however, note a reasonable way to decrease both anxiety and adolescent cannabis use: anxiety management strategies. Many studies suggest cannabis can help with adult anxiety, but studies also argue that cannabis, alcohol and tobacco use can adversely affect young, developing minds. Instead of blaming cannabis for anxiety disorders, communities should teach lifestyle tools that help kids reduce, manage and prevent stress, anxiety and panic attacks. Instilling these skillsets at an early age can help reduce the risk of all unhealthy substance use.
The difficulties with cannabis-harm studies doesn't mean the findings are without merit, but maybe the correlation is actually self-medicating cannabis use as opposed to biological causation. Self-medication is definitely a problem because it typically masks the symptoms temporarily as the disorder itself grows worse. Moreover, if you focus first on stopping the cannabis use, the young person will struggle to do so as long as the anxiety disorder persists. For this reason, a comprehensive approach that includes anxiety management strategies and mental health treatment is a superior approach than simply (and often times ignorantly) blaming cannabis.