The most important cannabis science stories of 2019

The biggest cannabis science story of 2019 didn’t take place in the laboratory. It happened in the emergency room, when all at once, consumers of counterfeit cannabis vape pens in the United States started to get seriously ill. The first cases of EVALI (e-cigarette, or vaping, product use associated lung injury) hit the media in August, and to date, at least 52 people have died from the condition, with thousands of cases reported across all 50 states.

At the outset, public health officials struggled to understand the cause of the outbreak and agree on a coherent response, and the mainstream media published all manner of confusing and conflicting reports. Until Leafly’s own team of investigative journalists broke a series of stories that accurately identified the source of the illnesses—additives like Vitamin E—then traced the supply line of tainted vape carts from Chinese counterfeiters to bootleg concentrate makers to illicit national distribution syndicates and finally to the local suppliers selling them on the underground market

Aside from the vaping story, numerous scientists and labs around the world published great new research on cannabis. Here are some of the most important studies on cannabis in 2019.

CBD for childhood autism

One vastly underreported study this year looked at cannabis as a potential treatment for Autism Spectrum Disorder (ASD) and for the first time produced clinical data showing clear benefits in pediatric cases.

The study, published in the journal Frontiers in Pharmacology, included 53 patients with a median age of 11 years old, and attempted to gauge improvement across a varied set of symptoms related to ASD after administering a daily does of THC and CBD. 

Patients showed significant improvement in hyperactivity symptoms (68.4%), self-injury and rage attacks (67.6%), sleep problems (71.4%), and anxiety (47.1%)—with 74.5% reporting overall improvement and less than 4% reporting worsening of symptoms.

Cannabis does not shrink your brain

Well, we’ve all heard reports that cannabis “shrinks your brain,” a claim that was breathlessly reported across the media after a few small studies seemed to suggest that heavy adolescent use could lead to a decrease in brain size. The headlines and bad puns write themselves, after all.

But the press paid almost no attention this February when the journal Nature published a study with a large sample size that used MRIs to examine the brains of 781 youth aged 14–22—including both occasional and heavy cannabis consumers—and determined that neither group showed significant structural differences in their brains when compared to non-consumers.

According to the study’s summary:

There were no significant differences by cannabis group in global or regional brain volumes, cortical thickness, or gray matter density, and no significant group by age interactions were found. Follow-up analyses indicated that values of structural neuroimaging measures by cannabis group were similar across regions, and any differences among groups were likely of a small magnitude. In sum, structural brain metrics were largely similar among adolescent and young adult cannabis users and non-users.

To be clear, cannabis use is certainly not completely harmless—particularly for the developing brains of adolescents—but that’s no excuse for skewed and misleading news coverage.

When it comes to dependence it really depends 

The latest version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) defines cannabis use disorder as “continued use of cannabis despite clinically significant impairment.” There’s a lot more detail on what that means exactly, including symptomatic behaviors and risk factors, but at the end of the day it’s really a judgement call based on your interpretation of what “clinically significant impairment” really means.

Especially once you accept that compared to the chronic abuse of cocaine, alcohol, and heroin, the problems associated with cannabis use disorder typically appear relatively mild. Largely because cannabis is far less physically harmful than any of those other drugs.

Which does not diminish the fact that cannabis dependency is a very real issue.

But it’s also a diagnosis that’s largely in the eyes of the beholder, as an intriguing study published this year in the International Journal of Drug Policy showed by comparing states with thriving medical cannabis programs to states with less or no legal access to medical cannabis. Not surprisingly, they discovered that greater access to cannabis led to greater reported use. But they also found that those same states had lower instances of cannabis use disorder.

So how can you have more people consuming cannabis and less problematic use? One hypothesis is that as people come to accept cannabis socially and as a legal product, their idea of what constitutes “clinically significant impairment” adjusts accordingly. Which means less people forced into rehab because they got arrested or failed a drug test and more help available for people who legitimately need it.

One last thing before you go under

If you find yourself facing a surgical procedure requiring sedation, you may want to discreetly let your anesthesiologist know that you consume copious amounts of cannabis. Because according to a new study from researchers in Colorado, you may need twice as much anesthetic to achieve the same effect as a non-user.

And that disparity could be a big enough to lead to serious problems in the operating room if not disclosed. As Corinna Yu, Assistant Professor of Clinical Anesthesia at the Indiana University School of Medicine, explained while encouraging patients to be forthcoming before undergoing a procedure.

“We have to destigmatize this so we can just be honest,” said Yu, who warns that withholding information about your cannabis use “could lead to intensive care unit stays and being on a ventilator. It’s a big deal.”