Hey there, time traveller!
This article was published 24/1/2018 – that’s before recreational cannabis was legal in Canada, so language and information in the article may be dated.
Dear Herb: My partner has been smoking pot multiple times a day for over 15 years. I am wondering about the health implications of using marijuana this often.
There is a lot of mixed messaging out there and I would like to know whether there are defined impacts to a person's physical and emotional well-being. Thanks!
— Juana Know
Dear Juana Know: To answer your question, I started searching through academic research for the most reliable information available about the potential effects of long-term, regular cannabis use by adults. As it turns out, lots of scientists and researchers also juana know the answer to this question, but there are relatively few unambiguous answers available.
This 2013 literature review by Australian researchers Wayne Hall and Louisa Degenhardt, for example, combed through dozens of studies on the adverse long-term effects of cannabis use — but even with all that research behind them, the authors warn that when it comes to cannabis and health outcomes, it can be particularly difficult to separate causation from correlation "because regular cannabis users are more likely to use alcohol, tobacco, and other illicit drugs, all of which adversely affect health."
The authors found conflicting evidence on many possible health outcomes related to long-term cannabis use. They determined that the "most probable adverse health effects of chronic cannabis smoking" for adults are:
* Cannabis dependence: The best-known research in this area suggests the risks of developing such a dependence appear to be lower than for other drugs. (I wrote about the limitations of that research in a previous edition of Dear Herb.)
* "Chronic bronchitis and impaired respiratory function in regular smokers," although different studies have reached conflicting conclusions on this.
* "Psychotic symptoms and disorders in heavy users." Researchers still aren't entirely clear on whether these symptoms and disorders are actually caused by cannabis use or vice versa, but those with a family history of psychotic disorders appear more likely to have problems in this area.
* "Cognitive impairment in those who initiate early and use daily for a decade or more." Again, it's still not clear whether cannabis actually causes cognitive impairment or whether those with "poorer cognitive functioning" are simply more likely to use cannabis.
Iffy, unresolved answers like those can be unsatisfying, I know. I called up Zach Walsh, a well-known associate professor of psychology at UBC who studies cannabis use, to ask him about why it's so hard to draw clear scientific conclusions about the direct health effects of cannabis.
Walsh brought up a phenomenon he calls "prohibition bias." Cannabis has been illegal and stigmatized for a long time now, he pointed out.
"If you have young people who are using cannabis every day, or very frequently, that's a young person that's breaking the law every day," he said.
Criminality is associated with negative outcomes, said Walsh.
"So it's very hard to tease apart the direct effects of cannabis," he said. "You have to look at people who are equivalent on all those other factors with and without cannabis, and nature doesn't really offer those kinds of options."
Cannabis legalization could offer the chance to learn more, he said.
Now, back to your question, Juana Know: I realize that all this information doesn't do much to help you determine whether your pot-smoking partner is putting his or her health at risk, and I'm sorry I can't offer a more definitive account of the health impacts of regular cannabis use.
But you know your partner on an individual level, so maybe it's not worth trying to figure out what scientists say about the average effects of cannabis on large populations.
'It's very hard to tease apart the direct effects of cannabis' - Zach Walsh, associate professor of psychology at UBC
Have you noticed a negative change in your partner's health over time? Has his or her behaviour changed in ways that make you anxious, or are they displaying symptoms that could conceivably be linked to their regular cannabis habit? If so, I'd say that's all the information you need to have an honest conversation about your concerns.
One final note: you did mention that your partner smokes multiple times a day. If it's the smoking that has you concerned, you might want to encourage your partner to switch to a vaporizer, which heats up the active ingredients in cannabis without actually burning the plant matter and creating smoke.
For a heavy user, switching from smoking to vaping could be a good way to reduce the potential respiratory harms of cannabis use. A quality vaporizer definitely costs more than rolling papers, but it could be a worthwhile investment for the person you love.
Got a question about cannabis? Herb answers your questions about legal consumption and growing, the law, etiquette — you name it, he'll look into it. Email firstname.lastname@example.org or to submit anonymously, fill out this form: