To some, cannabis is an amazing plant. Many claim it even has health benefits. But, then again, others still say it causes people to get "reefer madness" and jump out of windows, too.

Though whatever the leanings may be, no one has ever been able to answer definitively the age-old question of whether marijuana is a panacea or a problem. To do so, researchers at the University of Colorado are embarking on an exhaustive study, one that includes thousands of twins, on the ill effects (or not) of the controversial plant. 

The implications on legalization, however, might not be exactly fair. The players in it have a track record that hasn't exactly looked too kindly on weed in the past.

As more and more states are legalizing cannabis, things are now becoming scientifically testable. Researchers can now compare states where cannabis is legal versus those where it is not, to see what help or harm happens when cannabis is legalized. And now that years have passed since the first states went legal, there is growing data to figure out what's going on.

The study at CU is a first of its kind, and Dr. John Hewitt and Christian Hopfer MD, who are working it, hope to finally find out answers on what cannabis can do, or to be precise, what it doesn’t do. 

Hewitt says their mission is simple: “We’d like to know about how the change in the legalization is changing people’s behavior," he told 5280. The study employs the help of twins from Colorado and Minnesota —  exercises lauded by psychologists as the gold standard when studying humans because it’s easier to test a person with an exact carbon copy of themselves nearby to compare. Thousands of twins, whose usage of marijuana has been monitored for years, will now be followed for several more in order to assess the results of legalization.

Whether imbibed by bong, pipe, joint or aluminum can, the nation will finally know the truth about cannabis. However, the same researchers of the CU study think that the future for green is dark, with ties to substance abuse and increasing car crashes (even though the latter has been debunked, or at the very least contested because of a small data set). The same professors in this study, Hewitt and Hopfer, have also reported in the past that smoking weed makes you twice as likely to take other illicit drugs (again, also hotly contested by other experts in the field).

Previous studies by these two researchers (and their teams) suggest that genetically predisposed women are more likely to start smoking marijuana, too, regardless of whether anyone around them is toking up or not. Even for guys, problematic use appears to be down to genetic factors more, according to the doctors’ studies. Their previous research also suggests that a particular cannabinoid receptor haplotype may be the culprit for having “problems” with weed. Problem is, at this point, no one really knows.

Yet while all these studies appear to be worthwhile contributions to the study of cannabis, they are actually quite biased, and still set in a prohibition mindset. Ken Gershman, the manager of CDPHE Marijuana Research Grants Program points out, “Although there is much existing research on the negative cognitive and mental health effects of MJ use, much of it pre-dates (recreational) MJ legalization.”

The same professors in this study also reported that smoking weed makes you twice as likely to take other illicit drugs.

Unsurprisingly, the "narcs" of the drug war, The National Institute on Drug Abuse (NIDA), are the ones footing the bill for the CU Boulder study. Allen Shackelford, a board member of CDPHE MMJ Research Grants Program, has accused the NIDA of having “a history of funding studies that are intended to support their preconceptions about whether something is dangerous or not.”

In fact, the two star researchers on this University of Colorado project have had several studies funded by the NIDA, which also proposed negative results from cannabis use. To put it in perspective, News21 found the NIDA’s parent company, the National Institutes of Health, spent $1.4 billion on researching cannabis between 2008 and 2014. However only $300 million of that grant money went towards researching potential medical benefits, and all the $1.1 billion left was spent on studying addiction and abuse.  

Despite this study’s oblique origins, those thousands of twins are the first intrepid explorers of the drug dark age. In theory, they might hold the key to understanding the potential benefits, and potential harm, of a criminally under-studied substance. 

While it’s true the researchers accept funds from desperately anti-drug organizations, they say their interests still originate in using this long-term study, conducted over many years, as a soundboard for new ideas about cannabis. Even Hewitt admits the study will have serious limitations and will only be able to disprove ideas.

“We are probably in a better position to shoot down a causal relationship than we are to establish one," he says. "What we often find in the kinds of studies we do is that actually both the twin who uses the substance and the one who doesn’t are equally likely to show the apparent consequence”

By which he presumably means negative changes in mood or behavior, but also maybe positives as well?

Even its critics, like Gershman, still admit “ … this study will contribute to and inform policy discussions.”

So, whatever the results, at least the nation will have more of an idea about the true effects of widespread cannabis use. Several years from now, when the study is completed, it will be one of the first pieces of exhaustive, longitudinal research that explored the effects of cannabis legalization.