Does marijuana lead to violence? Authorities say there’s no clear hyperlink


Fox News speak show host Tucker Carlson poses for images in a Fox News Channel studio in New York on March two, 2017. (AP/Drew)

In the weeks due to the fact the attacks in Texas and Ohio, politicians and pundits have pointed the blame for mass shootings in various various directions.

Some known as out present gun laws. Some faulted white supremacy or President Donald Trump’s rhetoric on immigrants. Other individuals blamed video games or prescription drugs. 

Fox News speak show host Tucker Carlson has a new hypothesis to clarify why men and women to commit acts of intense violence: marijuana

Throughout an Aug. 27 interview with former New York Occasions reporter Alex Berenson, Carlson noted that the Dayton, Ohio, shooter had cocaine, Xanax and alcohol in his program when he attacked. 

“He was also recognized to be a extended-time user of marijuana,” Carlson stated. “It turns out, in truth, that lots of violent folks have been avid marijuana customers. Is there a connection?”

Berenson replied that that marijuana and violence are certainly linked, simply because cannabis can result in the onset of psychosis, which can in turn lead to violence. That is the obtaining at the heart of his new book, “Inform Your Kids: The Truth About Marijuana, Mental Illness, and Violence.”

“So, I do not consider it really is going way out on a limb to draw the connection then in between cannabis use, specifically I assume chronic use, and acts of violence,” Carlson responded. “Why is this not a thing that we’re pursuing extra aggressively?”

In the previous, we’ve debunked claims that mass shootings could be fueled by psychiatric drugs or Ritalin, a prescription for interest deficit hyperactivity disorder. We also rated a 2014 claim that men and women on pot “shoot every other … stab every other … strangle every other, drive below the influence, kill households” as Mainly False.

From speaking to specialists, we discovered that Berenson’s book goes far beyond what the readily available science really shows. Carlson presented no pushback as he praised Berenson for becoming “a voice in the wilderness,” providing viewers the incorrect impression about a cannabis hyperlink to violence.

The reality is that there’s no scientific consensus.

Berenson’s findings are disputed

In a statement to PolitiFact, a Fox News spokesperson stated Carlson’s segment was inspired by a New York Post op-ed that stated an anti-pot lobby group had compiled a list of mass shooters it claimed have been avid marijuana customers, which includes Dayton shooter Connor Betts, Aurora, Colo., shooter James Holmes, Tucson, Ariz., shooter Jared Loughner and Chattanooga, Tenn., shooter Mohammad Abdulazeez.

The spokesperson also pointed to a July study from British and Dutch researchers that discovered day-to-day use of marijuana — compared with nondaily use or no use — enhanced the likelihood of violence for men and women with psychotic problems such as schizophrenia.

But that does not imply casual pot smokers will necessarily turn violent. 

“This is absolute nonsense,” stated Katherine Newman, interim chancellor at the University of Massachusetts, Boston and the author of a book on college shootings. “There is no hyperlink whatsoever in between marijuana and intense violence.”

Other specialists told us there basically is not sufficient of a scientific consensus to draw Berenson’s conclusions.

The central premise of Berenson’s book — which argues against cannabis legalization — is summed up in these 3 lines: “Marijuana causes psychosis. Psychosis causes violence. The apparent implication is that marijuana causes violence.”

But the book has been a supply of controversy due to the fact it was published in January. A public letter signed by 100 scholars and clinicians refuted some of its central findings and accused Berenson of cherry-choosing information and presenting correlation as causation. 

Correlation vs. causation

Berenson relied mostly on two research to connect pot and psychosis, which includes a single from 1987 that stated “cannabis is accountable for in between 10% and 15% of schizophrenia situations.” 

The other is a 2017 study from the National Academies of Sciences, Engineering and Medicine that discovered “cannabis use is probably to raise the threat of building schizophrenia and other psychoses.” But it was not as definitive as Berenson created it out to be.

UCLA’s Ziva Cooper, a single of the study’s board members, disputed Berenson’s characterization of its findings, writing on Twitter that it “did not conclude that cannabis causes schizophrenia” but rather discovered an association in between the two.

On the connection in between marijuana and violence, Berenson pointed to anecdotes and information displaying that the initial 4 states to legalize pot — Alaska, Colorado, Oregon and Washington — saw increases in murders and aggravated assaults just after 2014.

But critics stated he cherry-picked that information, due to the fact Washington and Colorado legalized marijuana in 2012, not 2014, and there was a national uptick in homicides in 2015. 

Benjamin Hansen, professor of economics at Oregon University, constructed a model to estimate what the murder prices in Colorado and Washington would have looked like had pot not turn out to be legal.

“The homicide prices in Colorado and Washington have been really under what the information predicted they would have been provided the trends in homicides from 2000-2012,” he wrote in a weblog post.

In truth, other information could inform a a great deal various story. 

Cannabis consumption, and in particular heavy cannabis consumption, has been on the rise due to the fact 1992,” Mark Kleiman, a professor of public policy at New York University Wagner, told New York Magazine. “More than that period, national homicide prices have fallen extra than 50%.”

Plus, for every single study that is declared a hyperlink in between pot and violence, there are other folks that say the opposite. A 2013 Rand Corporation study commissioned by the federal government found that “marijuana use does not induce violent crime, and the hyperlinks in between marijuana use and house crime are thin.” 

As we noted in 2014, there is bound to be some overlap in between men and women who commit violent acts and men and women who smoke marijuana simply because of how preferred marijuana is. According to the United Nations, 192 million men and women worldwide applied marijuana at least after in 2016.

Even though marijuana does have some well being consequences, a turn toward violence is not extensively accepted as a single of them.

A lack of consensus

Behavioral sciences and drug policy specialists told us it is extensively accepted that marijuana and psychosis are linked. 

But there’s disagreement more than which comes initial — the marijuana use or the psychosis — and irrespective of whether a single causes the other.

Persons with psychotic illnesses are extra probably to use pot, but that could be simply because they have a tendency to turn to it in an work to self-medicate, stated Hansen, the Oregon University economist.

Even if causality could be assigned, it is also not clear from the readily available research irrespective of whether the drug unmasks psychotic symptoms in predisposed men and women or irrespective of whether it triggers the onset of psychosis completely, stated James Knoll, director of forensic psychiatry at Syracuse University.

The bottom line is that, devoid of becoming in a position to legally administer marijuana in a controlled laboratory setting, researchers can not inform irrespective of whether its use causes psychosis.

“In terms of irrespective of whether working with cannabis causes the improvement of psychotic problems, there is no consensus,” stated Matthew Johnson, associate professor of psychiatry and behavioral sciences at Johns Hopkins University. “The definitive research have but to be run.”

For the exact same motives, specialists are skeptical about the supposed connection in between marijuana and violence. 

Marijuana use is greater in young guys, men and women with critical adverse childhood experiences, antisocial character, low revenue, low education, use of other illicit substances,” Knoll stated. “All of these are properly recognized threat components for violence in their personal appropriate.”

So yes, lots of mass shooters have confirmed to be marijuana customers, specialists stated. But that does not imply pot created them pull the trigger.

Cannabis use is widespread all round, but it is most concentrated in groups with higher prices of violence,” stated Jonathan Caulkins, professor of operations analysis and public policy at Carnegie Mellon University. “So totally lots of men and women who commit violent acts have been heavy cannabis customers. The only argument is irrespective of whether the association is causal.”

If something, marijuana’s recognition really should make a supposed connection to violence much easier to spot, Knoll stated. “If there was a clear or powerful hyperlink, a single would anticipate it to be extra pronounced than we are obtaining.”


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