Marijuana Use in Youth from Bench to Bedside to Longitudinal Outlook

The issue of marijuana use and its potential legalization is salient for Canadians (and Americans), as evident in the political rhetoric around its legalization in recent years. Many Canadians have strong opinions about this matter. In September 2010, I gave a public talk at the downtown library in London, Ontario. The talk was titled, “Marijuana Use in Youth: Is It as Harmless as We’d Like to Think?” There were several notable occurrences regarding this talk.

The talk was announced in the local newspaper and the comments section of the online version accumulated hateful, rude, and accusatory comments to me, the upcoming speaker.

I started to receive threatening emails from individuals and/or organizations, apparently in other provinces, related to this talk. I had to contact the systems administrators of my hospital’s email account to filter them because even the titles of these emails were highly threatening and psychologically toxic.

During the talk, there were several middle-aged men in the audience who heckled at various points. They suggested that the published research results I was describing were from studies funded by the pharmaceutical industry (they were not) and therefore biased. Interestingly, I gave this talk to a mental health care audience 4 months earlier, and it was received with extremely positive feedback and support.

A parent in the audience pointed out a fact that I had discovered while preparing for this talk. The scientific research articles reporting study results of marijuana use were not available through public online search engines (Google, for example), but extensive lay opinions promoting marijuana use were. This has since changed somewhat in that scholarly article abstracts are now available via public search engines, but the full scientific articles mostly still are not.

Another astute parent queried, “You say that young people are less likely to be able to resist taking risks, resist peer pressure, and stop using addictive substances [because of the slower development of prefrontal cortex relative to other brain regions], but they’re also more likely to have negative effects of use.” So what are parents to do once their kid is using this substance regularly?

A writer from Mclean’s online magazine was in the audience and wrote an article about this talk. ¹ The event was picked up by other online news agencies as well. ²

Thus, there are strong opinions about this matter, and they are highly polarized. There may be a dearth of reliable information to ground this conversation, but that depends on your perspective. Some, including myself, would say that there is ample evidence that marijuana use by youth is problematic and believe that use of this substance among youth should not just be prevented from increasing but should actually be decreased.

There is a widespread perception, meanwhile, that marijuana use is harmless. This is particularly notable in the types of media used by youth, such as Twitter. ³ In addition, I have heard from youth and young adults in London and elsewhere that instructors at high schools and postsecondary schools have told them to use marijuana, “if they’re going to use anything this weekend because it’s the safest.”

Combining the actual risks associated with marijuana use in youth ⁴ and the belief that there is little to fear in its use, along with the lack of evidence for good and accessible treatments for youth with marijuana use disorders, ⁵ paints a dismal picture. Vulnerability to harmful effects of marijuana appears to be even more pronounced for youth poised to interact with psychiatric and other mental health care treatment providers because of the existence of neuropsychiatric risk factors. ^6,7 This combination of facts suggests that there is a momentous “storm” coming towards us of upcoming need for psychiatric and addictions services that we have no clear way to adequately meet or prevent. As providers of care, this should be of concern.

Yet the perception of risk is important. Perceived risk is inversely correlated with rates of use of any substance, including marijuana. ⁸ Interestingly, the perception of the relative risks of marijuana use has changed in recent decades. While tobacco use has dropped substantially among youth due to the growing perception that tobacco products cause health problems, marijuana use has remained relatively stable and is now higher than the rate of tobacco use. ⁹ Public education about tobacco use, decades after scientific data demonstrated negative health consequences of tobacco, has finally made a dent in the initiation of this substance in adolescents. Meanwhile, it appears that marijuana legalization will continue, leaving public education as the only medium through which to protect our youth.

The following 2 articles are additions to the armamentarium of evidence that, indeed, marijuana use in youth is not as harmless as we would like to think. The article by Coffey and Patton ⁴ describes research showing harmful effects of early marijuana use, particularly the long-term negative effects on functioning and evidence of the “gateway” nature of this substance. This team of researchers has done a brilliant job investigating the long-term effects of marijuana use in youth over the years, garnered from a data set that has proven to be of immense value to the world in addressing these questions.

The article by Renard et al., ¹⁰ describing basic science research findings, is potentially challenging to the clinician reader. However, basic science research in this field is critical. We will never be able to conduct longitudinal studies using an experimental design wherein youth are randomly assigned to frequent, early marijuana use versus no use. Nor will we likely ever be able to investigate the human brain, in the detail that we can the rodent brain, in close proximity to an experimental intervention. Thus, the article provided reviews our best and most accurate current knowledge of what occurs in mammalian brains when adolescents are exposed to cannabinoids.

It is hoped that these articles will be of use for educating ourselves as psychiatrists and, therefore, our colleagues and our patients, about the problems of early marijuana use. Perhaps we can thereby reduce the intensity and strength of the upcoming storm of psychiatric need that threatens mental health care services in our future.