CU Study On Thousands Of Twins Dispels Cannabis Gateway Drug Theory
Much to the chagrin of the “Just Say No” crowd, that theory about cannabis being a gateway drug just doesn’t fly, according to research coming out of the University of Colorado Boulder.
In 2018, CU researchers partnered with the University of Minnesota’s Center for Twin Family Research to study sets of twins who live in Colorado, where recreational cannabis sales have been legal since 2014, and some who live in Minnesota, where recreational pot is still banned. Over the next few years, researchers asked around 2,500 sets of twins, both users and non-users, an extensive set of questions to assess the effects of marijuana legalization and whether cannabis was a gateway drug.
After four years of data collection and analysis, the researchers recently reported that residents in both the legal and non-legal states had around the same rate of substance abuse or cognitive, psychological, social, relationship or financial problems. And cannabis use may even reduce alcohol-related problems, according to their findings.
To learn more about the results, we interviewed lead researcher Stephanie Zellers.
Westword: Was the gateway-drug thing still up for debate?
Stephanie Zellers: I’m not a believer in gateway theory. I think in some areas of psychology, it’s sort of viewed as an old-school theory that we’ve moved past. I personally believe in a theory about general liability. It’s not like using cannabis made you do illegal drugs that you wouldn’t have done had you not been using cannabis. I believe more that you have a general risk for using drugs, and that there are no alcohol or cannabis “genes.” You’re at a general risk for a lot of these problems, and the way it develops depends on things like the drugs available around you and what your family, peers, community are like. So I wasn’t surprised to see our results.
Is this twins and cannabis project used for multiple studies? We’ve seen it pop up recently in your published study about the rates of marijuana use in legalized states.
It’s an internal data source. It’s most widely used by researchers associated with CU Boulder and Anschutz [Medical Campus], but external researchers can use it as well, pending applications. I actually started grad school at CU Boulder and then moved with my advisor to the University of Minnesota, so we’ve kept that active collaboration going between Minnesota and Colorado.
In this study, you score a lot of factors such as financial distress, employment, emotional detachment, addiction and cognitive problems between users and non-users, and found that there wasn’t a recognizable difference between the two groups. How did you go about scoring such intimate factors in peoples’ lives?
We have a set of measures that have been used previously in many studies, which sort of gives us support in measuring what we think they’re measuring, especially in some of those personality measurements, because those are sort of newer, widely accepted ways to score things. We typically have multiple items for something like emotional detachment, with questions asking people how they feel and behave. Then we add those totals together. For something like unemployment, we ask to make sure that a person is unemployed but not necessarily job-seeking, like a full-time student or homemaker. We also ask about work demotions, having hours cut and as many questions as possible per concept to make sure we’re addressing these from multiple angles.
What demographic cannabis trends did you notice from the study?
There are usually trends, especially in the drug-use questions. Men tend to use at higher rates than women, and we also see age-related trends. Younger individuals tend to use more substances than older individuals. There are definitely demographic trends, like how often people are using cannabis, which sort of goes with how old you are. But I guess the important thing here is that we don’t see differences based on legalization.
People always talk about the obstacles of cannabis studies because of federal prohibition. What, if any, did you face with this one?
The biggest obstacle was that we were hoping to investigate more products. In the legal market, there’s kind of a wider range of products and concentrations that are more easily available. We were hoping to compare using really high concentrate, like dabs, to someone who is smoking [flower] or using edibles or teas. We just don’t have enough people saying what products or milligrams in their edibles that they’re using, though, especially in states where it’s not legal. We still don’t really have people saying what exact products they use, so it’s more difficult to answer those detailed questions beyond “Are you using cannabis or not?”
Getting that standardization of what’s being used and how much is still difficult, but it’s definitely getting easier, especially in legal states, where they can just look at the package and tell us how many milligrams are in that edible. But people in other states, they don’t know that kind of stuff.
After completing the study, you told CU that you still wanted to figure out who’s most at risk from legal cannabis and who’s benefiting the most. Do you have any leads on answers to those questions yet?
We do a little bit, especially the question of who’s at the most risk. With this most recent study, we wanted to see who was at more risk between people in legal states or non-legal states, and we didn’t really see any differences, besides that residents in legal states use more cannabis, which is kind of obvious. But a lot of things seem obvious, and you still need evidence to back it up. We also looked at male and female genders and didn’t see any differences there.
The most interesting thing we looked at was whether people were at higher risk for drug use or behavioral problems that are related to drug use. We looked at childhood symptoms and disorders that tend to predict adult substance problems, and then we also looked at adult symptoms, like anti-social personality disorder. We asked if people higher with those symptoms would be affected more by legalization, and the answer was also: not much.
What long-term cannabis effects do you want to see play out?
That’s the last study in this area that I’m currently working on. It’s not published yet, but we’ve done most of the research and are waiting to get it peer-reviewed.