All the Things the New Anti-Weed Crusade Gets Horribly Wrong

High Wire is Maia Szalavitz's reported opinion column on drugs and drug policy.

Stories about cannabis are like catnip, so it was only matter of time before someone with an aura of credibility decided to capitalize on the growing consensus in favor of legalization with an extreme contrarian perspective. And what could better troll the legalizers than arguing, in essence, that Reefer Madness is real—and pot really does cause insanity, murder, and mayhem?

Enter former New York Times reporter Alex Berenson, whose new book Tell Your Children: The Truth about Marijuana, Mental Illness and Violence, attempts to do just that. Its main title is literally taken from the original name for that much-mocked 1936 film.

Sadly, judging from the publicity he’s received so far—with op-eds in the New York Times and Wall Street Journal, a supportive Malcolm Gladwell take in the New Yorker and even glowing coverage in Mother Jones—today’s media is still happy to toss critical thinking aside and revive the idea of marijuana as a menace that must be suppressed. But that notion remains as noxious as ever, even if pot is not the innocuous wonder-drug its most ardent defenders might like to think it is.

The book’s central claim—that marijuana causes violence by inducing schizophrenia and other psychotic disorders—relies on a chain of spurious reasoning that falls apart when examined closely. The rest of it is just as specious, propping up a set of laws that were clearly racist in intent and have continually produced racist outcomes, even as the author insists he favors a modest form of decriminalization and is aware of the racial element to prohibition.

Let’s start with the connection between marijuana use and psychotic disorders. While marijuana can indeed cause transient psychosis in some people, a causal connection to chronic psychotic disorders like schizophrenia is much less clear. Studies do find that heavy marijuana use is associated with at least a doubling of risk for schizophrenia—and in cases where people have a family history, an increased risk for earlier onset to the disorder.

But we still don’t really know whether a third factor—such as a genetic predisposition that creates both an affinity for weed and an increased risk of psychosis—accounts for this link. According to Matthew Hill, an associate professor of neuroscience at the University of Calgary in Canada, candidate genes that do both have already been identified.

Moreover, there’s always been a massive problem for people who try to use the weed and psychosis connection to argue for prohibition. That is, when countries experienced their first exponential jump in modern marijuana use—generally between the 1960s and the 1980s—psychosis rates either remained the same or even, in some, declined. For example, a 2003 Australian study compared people born in the 1940s through the 1970s and found no correlation between rates of diagnosis, even though many more people born in the 50s and later smoked weed. A 2012 British study found schizophrenia rates to be stable between 1950 and 2009— a time during which cannabis use exploded in that country.

“Given that the epidemiology of schizophrenia has not changed over time as cannabis use has become more prevalent, nor does it really vary around the world in a manner relating to rates of cannabis use… [I] would argue that this statistical relationship is probably not causal,” Hill said.

Essentially, while correlation doesn’t necessarily mean causation, if two factors aren’t even reliably linked to each other, it’s pretty hard to argue that one causes the other.

To deal with this, Berenson claims—as many have before him, in many different decades—that today’s marijuana is basically a new and more dangerous drug. The percentage of the active ingredient in the drug, THC, has risen from “less than 5 percent” he writes, to the availability at some dispensaries of potencies of 25 percent or higher. He cites studies showing recent increases in rates of psychotic disorders in Scandinavian countries, which have also seen growing marijuana use.

It’s actually unclear how much potency has increased over time. But even if it has, why would marijuana suddenly start causing new chronic psychotic disorders now? Hashish, which can have a THC content of more than 40 percent, has existed for centuries, and high THC marijuana has been available to those willing to pay for it since the 1970s, if not earlier.

By the way, THC remains only a partial activator of key cannabinoid receptors, which means its effects can only go so far. Drugs that fully activate the receptor—like “synthetic weed” product Spice or K2—appear to be much more dangerous. (Ironically, these drugs are chiefly known for popularity among groups with reduced access to real marijuana: homeless people who can’t afford it and people who face drug-testing that will pick up marijuana but not synthetics.)

Further, the link between psychosis and violence is itself complex. The majority of people who suffer from psychotic disorders do not commit violent crimes and less than one fifth of all homicides in the US are associated with schizophrenia. Substance use by people with psychosis is one of the strongest predictors of violence by them, but this risk is not specific to pot. Alcohol, meth, cocaine, and other drugs all increase risk. In fact, one of the strongest predictors of violence in general, violence during psychosis, and addictive disorders overall is victimization including domestic violence and abuse during childhood.

Both criminologists and economists have been affronted by the way Berenson and his media enablers have selectively employed data to make claims about violence and psychosis. For instance, in his Times op-ed, Berenson claimed the first four states to legalize recreational marijuana use and sales saw a sharp increase in homicide rates since 2014.

However, the choice of that year as a cutoff point is questionable and telling, as Jesse Singal pointed out in New York—2014 was the recent national low-point for homicide rates. Basically, many states saw a rise beginning around that time, and, you can’t just compare state homicide rates in legal and non-legal marijuana states without taking into account other variables that may affect them. This is why people run studies of these issues instead of simply presenting raw and often misleading numbers.

“That ignores other trends and confounders also occurring in the background [like] the age of the population [and] gun ownership,” said Benjamin Hansen, professor of economics at the University of Oregon. Using appropriate controls, Hansen compared the homicide rates in Colorado and Washington to projections made with data from comparable states from 2000 to 2016. He found that the rates in legal-weed states were lower than predicted: in other words, if marijuana legalization had any effect, it may have been a small but positive one.

“The claim that cannabis increases criminal violence seems to be based on a misunderstanding of the medical literature on the one hand and some over-hasty statistical work on reported crime rates on the other,” said Mark Kleiman, director of the Crime and Justice Program at NYU's Marron Institute of Urban Management and a longtime skeptic of commercialized legalization. “No expert I know has cannabis-induced violence anywhere near the top of the list of things to worry about as prices fall and heavy use expands.”

Added Hill, “What frustrates me the most about what Berenson is doing is that there are tangible harms associated with cannabis use, especially when it relates to earlier onset of use and the use of higher potency products, but a lot of these harms are more directly associated with the development of dependency and the impact this can have on someone’s life.”

But instead of focusing on targeted campaigns that would help protect the most vulnerable people, “We are now going to spend the next five years dealing with pearl-clutching screams from the alarmists about how cannabis causes schizophrenia and homicide,” he said.

Berenson also claims—in line with the widely-debunked "gateway theory"—that marijuana use is strongly linked to increased use of other drugs like opioids and cocaine. Once again, he ignores data to the contrary—such as the Dutch experience of quasi-legalization, which has not found increased rates of other drug use. And he dismisses the now repeatedly-replicated finding of reduced rates of opioid prescriptions, addiction and overdose associated with the availability of legal medical marijuana.

Sadly, Malcolm Gladwell seemed to fall for this too, writing in the New Yorker:

Actually, there are far more than two possibilities, and one he doesn’t mention is the most likely explanation. That is, people who like altering their consciousness—or hate their experience of the world—are likely to try many ways of getting out of their heads, and if you get marijuana from a dealer, that person likely can introduce you to the more dangerous drugs. Indeed, the Dutch research suggests this: separate the market for marijuana from that for other drugs and you close the gate. (Gladwell also repeatedly emphasizes how much we "don't know" about pot, which is odd given we probably know more about marijuana than we do about the overwhelming majority of FDA approved drugs. None of these have had the added safety valve of the National Institute on Drug Abuse, a government agency, spending decades and millions of dollars searching for—and identifying not so much—harm.)

To give him credit, Berenson does recognize that continued criminalization of marijuana possession is a lost cause. But he doesn’t realize or just can’t reckon with the fact that that this will do nothing to protect the most vulnerable people in society.

Prohibition has clearly not been a deterrent: more than half of young adults in the country have tried marijuana, and simply removing penalties for possession will not touch the risks associated with a continued black market. In an illegal market, higher potency will be more attractive because smaller products are easier to hide, and many dealers will not refuse to sell to teens.

In a legal market, however, potency can be regulated. Which brings us to another irony: marijuana itself contains a chemical that has potential to treat schizophrenia, which mitigates the effects of THC. Popularly known as CBD, it has been shown in two clinical trials to reduce schizophrenia symptoms without producing a high—one found that it was as effective as current drugs, with none of their terrible and sometimes irreversible side effects. In a legal market, levels of CBD and THC can be regulated to reduce risk, and CBD could finally be studied properly as an alternative to some of the most harmful drugs in psychiatry.

Worst of all, by providing ammo for continued prohibition, Berenson callously dismisses the profound damage done by the war on marijuana to people of color. In his epilogue, he writes:

Yes, marijuana arrests disproportionately fall on minorities, especially the black community. But marijuana’s harms also disproportionately fall on the black community. Black people are more likely to develop cannabis use disorder. They are also more likely to develop schizophrenia—and much more likely to be perpetrators and victims of violence. Given marijuana’s connection with mental illness and violence, it is reasonable to wonder whether the drug is partly responsible for those differentials.

It would take another whole article to debunk the racist assumptions packed into that paragraph. For one, cannabis use disorder rates are actually probably lower in black communities when factors like socioeconomic status are taken into account, and there are many far more documented contributors to schizophrenia risk (poverty, living in cities, immigration, childhood trauma—to name just a few). The major risk factors for violence are similarly diverse, and to claim marijuana makes a significant contribution based on the level of evidence he presents is, well, premature.

Suffice it to say, Berenson completely fails to deal with the role of marijuana arrests in feeding mass incarceration. The largest number of arrests in any category in the US is for drug crimes, and of these 40 percent are for marijuana, with 90 percent of marijuana arrests involving simple possession. While these arrests often do not lead to incarceration, they typically begin and then sustain the process of feeding people into the criminal prosecution system and reducing their chances for higher education and career success.

And black and Latinx people are arrested, prosecuted and incarcerated for marijuana crimes at rates far disproportionate to their populations. In New York, for example— which was supposed to have decriminalized marijuana possession in the 1970s—the arrest rate for blacks for marijuana is eight times that for whites.

“Three big things are missing from the conversation that he is trying to trigger: one is any assessment of the harms of prohibition, he pooh-poohs racism, and he never weighs the cost of millions of arrests,” said Maria McFarland Sanchez-Moreno, executive director of the pro-reform Drug Policy Alliance. “Knowing how many lives have been destroyed by the criminal justice approach, it’s so irresponsible to put this out there.”

Trolling the libs who make overblown claims about marijuana’s harmlessness may be one thing. But suggesting that its prohibition does more good than harm in the face of so much evidence to the contrary is its own form of insanity.

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