What’s hot this summer in cannabinoid research
Four academic articles highly distributed on social media from June — August
Articles involving cannabinoid research sometimes can get a lot of media attention. Anyone that knows me knows that one of my biggest pet peeves is bad science reporting — either totally missing the point of the article, generalizing it way too far, or even incorrectly reporting findings.
So let’s take a look at what new research was hot this summer, and see how it was analyzed.
Note: I’ve found these articles by looking at Altmetric Attention Scores — a tool which reports a weighted count of online attention, by looking at social media shares, news outlet reports, blogs, Wikipedia, citations in public policy, etc.
1. Sex-dependent effects of cannabis-induced analgesia
Cooper and Haney. Available online August 5 (published October 1).
Altmetric Attention Score: 793
http://dx.doi.org/10.1016/j.drugalcdep.2016.08.001
The question: Are there male/female differences in therapeutic effects of cannabis?
The study: Sex differences related to cannabis use and abuse have yet to be fully investigated, and may be especially important given reports that women have reportedly greater potential for abuse liability. While previous studies have looked at sex differences in relation to pain perception in rats, this has yet to be examined in humans.
This retrospective study analyzed male and female differences to perception of pain with a cold water pressor test. These researchers “suggest” that men seemed to have more analgesia compared to women, which may imply that women intending to use THC-containing cannabis for pain, may not have the same success as men. However, there are several limitations¹ to this study, which the authors do address.
In summary: This is a first in human trial investigating a new concept. Generalizations from this study are difficult; however, results do suggest that further research is needed.
Reach: This is one of those studies which spread like wildfire through the news (99 news outlet reports — though to be fair, it was a lot of the same article redistributed), with catchy headlines like “Smoking cannabis gives men more pain relief than women.” Most of the articles that I’ve read were careful about not making too bold of statements (other than the headlines). It’s surprising then, for all the news attention, that there have only been two tweets (though, remember that the original paper must be cited to contribute to this score, not the corresponding articles). The Altmetric Attention Score received actually puts this paper in the top 5% of all papers of all time. Does it deserve to receive more attention than other papers out there? I’m not so sure.
2. Acute Poisonings from Synthetic Cannabinoids — 50 U.S. Toxicology Investigators Consortium Registry Sites, 2010–2015
Riederer et al. Published July 15.
Altmetric Attention Score: 414
http://dx.doi.org/10.15585/mmwr.mm6527a2
The question: What illicit synthetic cannabinoids are currently being abused in the US?
The study: Now if the last article didn’t deserve attention, I’m pretty sure that this one does. This is an extensive report from Rierderer et al. which looks at data collected from toxicological reporting centres across the US. This type of data provides important information about currently abused street drugs and can inform a lot of important policy decisions (like where money should be invested for antidotes, fighting spread of current drugs, etc.).
In summary: There has been a significant increase in reported toxicity due to consumption of illegal synthetic cannabinoids in the last few years, and there’s a major gap in the ability to clinically identify these drugs (there are no drug standards for comparison), ability to treat for toxicity specifically for these drugs, and targeted prevention measures (eg, education).
Reach: Since this article has actual stats about current affairs, several news outlets have used this study to back up their local reports about increased synthetic cannabinoid use. In particular, several outlets have used this article in reference to increases in “spice” (or K2) usage (such as the 33 “zombies” that were sent to hospital in Brooklyn two days before the article was released). This is a very important paper, so I wouldn’t be surprised if the Altmetric Attention Score keeps growing, particularly if it’s later used to inform policy (as it should be).
3. One Minute of Marijuana Secondhand Smoke Exposure Substantially Impairs Vascular Endothelial Function
Wang et al. Published July 27.
Altmetric Attention Score: 369
http://dx.doi.org/10.1161/JAHA.116.003858
The question: What does secondhand marijuana smoke do to people?
The study: Secondhand tobacco smoke impairs vascular endothelial function, which contributes to cardiovascular disease and death. The effects of secondhand marijuana smoke, prior to this study, had yet to be explored. The authors found that secondhand marijuana smoke exposure altered vascular endothelial function, which was independent of THC content or rolling paper. This impairment persisted for 90 minutes, even after only one minute of exposure. Overall, data suggest that secondhand marijuana smoke should therefore be avoided. These findings have potentially important implications for public health policy, particularly if legalization of marijuana were to occur, and public exposure increased. Although there have been several public health campaigns educating about the dangers of secondhand tobacco smoke, the same has not been done for marijuana, and therefore it is possible that those using marijuana may not realize the implications.
In summary: Compared with secondhand tobacco smoke, secondhand marijuana smoke has similar negative effects on endothelial function which is independent of THC and rolling paper.
Reach: Even though this study is quite a preliminary, it does have very important implications, so one would expect that the reach of this article would be quite wide. As expected, several news reports picked up this study, with headlines which ranged from “is weed smoke bad for you” to the unjustifiably definitive “marijuana smoke deadlier than tobacco smoke.” Altmetric reports only 51 tweets (of the article directly), which I feel is actually quite surprisingly low, given the potential public implications (even now, while attending concerts, for example).
4. Endocannabinoid Modulation of Orbitostriatal Circuits Gates Habit Formation
Gremel et al. Published online June 15.
Altmetric Attention Score: 286
http://dx.doi.org/10.1016/j.neuron.2016.04.043
The question: What molecules are involved in habit formation?
The study: This is another study that popped up that I was actually very interested to read for personal curiosity (I’ve just finished reading The Power of Habit), even though I’m definitely not an expert by any means in this area. The gist of this paper is exploring systems involved with action control and/or decision making — specifically, turning goal-directed behaviours into habits. Through imaging studies, certain regions of the brain have been previously identified as important contributors, but the molecular pathways involved were previously unknown. Theses findings are a really good example of how little we actually know about the endocannabinoid system in normal function in the body, and has the potential to make significant impacts in the field of behavioural psychology, as well as our general understanding of how the brain works. Further understanding of this pathway and its controls may lead to better understanding of disorders such as OCD and addiction.
In summary: CB1 activation in the orbitostriatal loop contributes to switching of goal-directed actions to habitual actions (and with deletion of CB1, this switch does not occur)
Reach: Not surprisingly, most of the news articles are based solely off of the provided press release from the authors’ institution. This is quite a complex article, so I’m not that surprised to find few taking this article on. One exception I did find might have found it better to stick to the script — erroneously oversimplifying the endocannabinoid system in a few cases. However, the findings in this article could have very easily been over generalized, and I’m really very surprised to see that they weren’t. Maybe the lesson here is that if you want to ensure you have the correct type of discussion surrounding your work, that you make your own press release (although, I guess we already knew that from the chocolate “study”).
Have any paper you thought should have made it on this list? Let’s talk about it! Leave me a comment below.
1. Limitations include, but are not limited to: small sample size, only 21 men and 21 women were used; a retrospective design, with some prospective “add ins”; a healthy population (eg, not experiencing pain); no mention of how long the participants had used cannabis prior to the study (but reported that all “smoked >3 cannabis cigarettes at least four times a week for the previous four weeks before screening”, though variability between daily use of participants high); and most importantly, suggested sex differences were found by looking at the statistical interactions in the data, however, the authors made it seem like if a direct comparison were made there was no statistical significance (there are many reasons why this may or may not be true, and could be resolved with a much larger sample size). (Jump back)
