MARIJUANA, MENTAL ILLNESS AND VIOLENCE
by Alex Berenson,
author of Tell Your Children: The Truth About Marijuana, Mental Illness And
Imprimis, January 2019, Vol.48, #1
northwest of New York City is a hospital that looks like a prison, its drab
brick buildings wrapped in layers of fencing and barbed wire. This grim
facility is called the Mid-Hudson Forensic Psychiatric Institute. It’s one of
three places the state of New York sends the criminally mentally ill—defendants
judged not guilty by reason of insanity.
Until recently, my
wife Jackie—Dr. Jacqueline Berenson—was a senior psychiatrist
there. Many of Mid-Hudson’s 300 patients are killers and arsonists. At least
one is a cannibal. Most have been diagnosed with psychotic disorders like
schizophrenia that provoked them to violence against family members or
A couple of years
ago, Jackie was telling me about a patient. In passing, she said something like, Of course he’d
been smoking pot his whole life.
Of course? I
Yes, they all
I was surprised,
to say the least. I tended to be a libertarian on drugs. Years before, I’d
covered the pharmaceutical industry for The New York Times. I was aware of
the claims about marijuana as medicine, and I’d watched the slow spread of
legalized cannabis without much interest.
Jackie would have
been within her rights to say, I know what I’m talking about, unlike you.
Instead she offered something neutral like, I think that’s what the big studies say. You
should read them.
So I did. The big
studies, the little ones, and all the rest. I read everything I could find. I
talked to every psychiatrist and brain scientist who would talk to me. And I
soon realized that in all my years as a journalist I had never seen a story
where the gap between insider and outsider knowledge was so great, or the
stakes so high.
I began to wonder
why—with the stocks of cannabis companies soaring and politicians
promoting legalization as a low-risk way to raise tax revenue and reduce
crime—I had never heard the truth about marijuana, mental illness, and
Over the last 30
years, psychiatrists and epidemiologists have turned speculation about
marijuana’s dangers into science. Yet over the same period, a shrewd and
expensive lobbying campaign has pushed public attitudes about marijuana the
other way. And the effects are now becoming apparent.
you think you know about the health effects of cannabis, almost everything
advocates and the media have told you for a generation, is wrong.
They’ve told you
marijuana has many different medical uses. In reality marijuana and THC, its
active ingredient, have been shown to work only in a few narrow conditions.
They are most commonly prescribed for pain relief. But they are rarely tested
against other pain relief drugs like ibuprofen—and in July, a large
four-year study of patients with chronic pain in Australia showed cannabis use
was associated with greater pain over time.
They’ve told you
cannabis can stem opioid use—“Two new studies show how marijuana can help
fight the opioid epidemic,” according to Wonkblog, a Washington Post website,
in April 2018— and that marijuana’s effects as a painkiller make it a
potential substitute for opiates. In reality, like alcohol, marijuana is too
weak as a painkiller to work for most people who truly needopiates,
such as terminal cancer patients. Even cannabis advocates, like Rob Kampia, the
co-founder of the Marijuana Policy Project, acknowledge that they have always
viewed medical marijuana laws primarily as a way to protect recreational users.
As for the
marijuana-reduces-opiate-use theory, it is based largely on a single paper
comparing overdose deaths by state before 2010 to the spread of medical
marijuana laws— and the paper’s finding is probably a result of simple
geographic coincidence. The opiate epidemic began in Appalachia, while the
first states to legalize medical marijuana were in the West. Since 2010, as
both the epidemic and medical marijuana laws have spread nationally, the
finding has vanished. And the United States, the Western country with the most
cannabis use, also has by far the worst problem with opioids.
individual users—a better way to trace cause and effect than looking at
aggregate state-level data—consistently shows that marijuana use leads to
other drug use. For example, a January 2018 paper in the American Journal
of Psychiatry showed that people who used cannabis in 2001 were
almost three times as likely to use opiates three years later, even after
adjusting for other potential risks.
Most of all,
advocates have told you that marijuana is not just safe for people with
psychiatric problems like depression, but that it is a potential treatment for
those patients. On its website, the cannabis delivery service Eaze offers the
“Best Marijuana Strains and Products for Treating Anxiety.” “How Does Cannabis
Help Depression?” is the topic of an article on Leafly, the largest cannabis
website. But a mountain of peer-reviewed research in top medical journals shows
that marijuana can cause or worsen severe mental illness, especially psychosis,
the medical term for a break from reality.
smoke marijuana regularly are about three times as likely to develop
schizophrenia, the most devastating psychotic disorder.
exhaustive review, the National Academy of Medicine found in 2017 that
“cannabis use is likely to increase the risk of developing schizophrenia and
other psychoses; the higher the use, the greater the risk.” Also that “regular
cannabis use is likely to increase the risk for developing social anxiety
Over the past
decade, as legalization has spread, patterns of marijuana use—and the
drug itself—have changed in dangerous ways.
not led to a huge increase in people using the drug casually. About 15 percent
of Americans used cannabis at least once in 2017, up from ten percent in 2006,
according to a large federal study called the National Survey on Drug Use and
Health. (By contrast, about 65 percent of Americans had a drink in the last
year.) But the number of Americans who use cannabis heavily is
In 2006, about
three million Americans reported using cannabis at least 300 times a year, the
standard for daily use. By 2017, that number had nearly tripled, to eight
million, approaching the twelve million Americans who drank alcohol every day.
Put another way, one in 15 drinkers consumed alcohol daily; about one in five
marijuana users used cannabis that often.
today are also consuming a drug that is far more potent than ever before, as
measured by the amount of THC—delta-9-tetrahydrocannabinol, the chemical
in cannabis responsible for its psychoactive effects—it contains. In the
1970s, the last time this many Americans used cannabis, most marijuana
contained less than two percent THC. Today, marijuana routinely contains 20 to
25 percent THC, thanks to sophisticated farming and cloning techniques—as
well as to a demand by users for cannabis that produces a stronger high more
quickly. In states where cannabis is legal, many users prefer extracts that are
nearly pure THC. Think of the difference between near-beer and a martini, or
even grain alcohol, to understand the difference.
These new patterns
of use have caused problems with the drug to soar. In 2014, people who had
diagnosable cannabis use disorder, the medical term for marijuana abuse or
addiction, made up about 1.5 percent of Americans. But they accounted for
eleven percent of all the psychosis cases in emergency rooms—90,000
cases, 250 a day, triple the number in 2006. In states like Colorado, emergency
room physicians have become experts on dealing with cannabis-induced psychosis.
often argue that the drug can’t be as neurotoxic as studies suggest, because
otherwise Western countries would have seen population-wide increases in
psychosis alongside rising use. In reality, accurately tracking psychosis cases
is impossible in the United States. The government carefully tracks diseases
like cancer with central registries, but no such registry exists for
schizophrenia or other severe mental illnesses.
On the other hand,
research from Finland and Denmark, two countries that track mental illness more
comprehensively, shows a significant increase in psychosis since 2000,
following an increase in cannabis use. And in September of last year, a large
federal survey found a rise in serious mental illness in the United States as
well, especially among young adults, the heaviest users of cannabis.
According to this
latter study, 7.5 percent of adults age 18-25 met the criteria for serious
mental illness in 2017, double the rate in 2008. What’s especially striking is
that adolescents age 12-17 don’t show these increases in cannabis use and
severe mental illness.
A caveat: this
federal survey doesn’t count individual cases, and it lumps psychosis with
other severe mental illness. So it isn’t as accurate as the Finnish or Danish
studies. Nor do any of these studies prove that rising cannabis
use has caused population-wide increases in psychosis or other mental
illness. The most that can be said
is that they offer intriguing evidence of a link.
people with mental illness do not like discussing the link between
schizophrenia and crime. They fear it will stigmatize people with the disease.
“Most people with mental illness are not violent,” the National Alliance on
Mental Illness (NAMI) explains on its website. But wishing away the link can’t
make it disappear. In truth, psychosis is a shockingly high risk factor for
violence. The best analysis came in a 2009 paper in PLOS Medicine by
Dr. Seena Fazel, an Oxford University psychiatrist and epidemiologist.
Drawing on earlier
studies, the paper found that people with schizophrenia are five times as
likely to commit violent crimes as healthy people, and almost 20 times as
likely to commit homicide.
statement that most people with mental illness are not violent is of course
accurate, given that “most” simply means “more than half”; but it is deeply
misleading. Schizophrenia is rare. But people with the disorder commit an
appreciable fraction of all murders, in the range of six to nine percent.
“The best way to
deal with the stigma is to reduce the violence,” says Dr. Sheilagh Hodgins, a
professor at the University of Montreal who has studied mental illness and
violence for more than 30 years.
marijuana-psychosis-violence connection is even stronger than those figures
suggest. People with schizophrenia are only moderately more likely to become
violent than healthy people when they are taking antipsychotic medicine and
avoiding recreational drugs. But when they use drugs, their risk of violence
skyrockets. “You don’t just have an increased risk of one thing—these
things occur in clusters,” Dr. Fazel told me.
alcohol, the drug that psychotic patients use more than any other is cannabis:
a 2010 review of earlier studies in Schizophrenia Bulletin found
that 27 percent of people with schizophrenia had been diagnosed with cannabis
use disorder in their lives. And unfortunately—despite its reputation for
making users relaxed and calm—cannabis appears to provoke many of them to
A Swiss study of
265 psychotic patients published in Frontiers of Forensic Psychiatry last
June found that over a three-year period, young men with psychosis who used
cannabis had a 50 percent chance of becoming violent. That risk was four times
higher than for those with psychosis who didn’t use, even after adjusting for
factors such as alcohol use. Other researchers have produced similar findings.
A 2013 paper in an Italian psychiatric journal examined almost 1,600
psychiatric patients in southern Italy and found that cannabis use was
associated with a ten-fold increase in violence.
The most obvious
way that cannabis fuels violence in psychotic people is through its tendency to
cause paranoia—something even cannabis advocates acknowledge the drug can
cause. The risk is so obvious that users joke about it and dispensaries
advertise certain strains as less likely to induce paranoia. And for people
with psychotic disorders, paranoia can fuel extreme violence. A 2007 paper in
Journal of Australia on 88 defendants who had committed homicide
during psychotic episodes found that most believed they were in danger from the
victim, and almost two-thirds reported misusing cannabis—more than
alcohol and amphetamines combined.
Yet the link
between marijuana and violence doesn’t appear limited to people with preexisting
psychosis. Researchers have studied alcohol and violence for generations,
proving that alcohol is a risk factor for domestic abuse, assault, and even
murder. Far less work has been done on marijuana, in part because advocates
have stigmatized anyone who raises the issue. But studies showing that
marijuana use is a significant risk factor for violence have quietly piled up.
Many of them weren’t even designed to catch the link, but they did. Dozens of
such studies exist, covering everything from bullying by high school students
to fighting among vacationers in Spain.
In most cases,
studies find that the risk is at least as significant as with alcohol. A 2012
paper in the Journal of Interpersonal Violence examined a federal
survey of more than 9,000 adolescents and found that marijuana use was
associated with a doubling of domestic violence; a 2017 paper in Social Psychiatry
and Psychiatric Epidemiology examined drivers of violence among
6,000 British and Chinese men and found that drug use—the drug nearly
always being cannabis—translated into a five-fold increase in violence.
Today that risk is
translating into real-world impacts. Before states legalized recreational
cannabis, advocates said that legalization would let police focus on hardened
criminals rather than marijuana smokers and thus reduce violent crime. Some
advocates go so far as to claim that legalization has reduced
violent crime. In a 2017 speech calling for federal legalization, U.S. Senator
Cory Booker said that “states [that have legalized marijuana] are seeing
decreases in violent crime.” He was wrong.
The first four
states to legalize marijuana for recreational use were Colorado and Washington
in 2014 and Alaska and Oregon in 2015. Combined, those four states had about
450 murders and 30,300 aggravated assaults in 2013. Last year, they had almost
620 murders and 38,000 aggravated assaults—an increase of 37 percent for
murders and 25 percent for aggravated assaults, far greater than the national
increase, even after accounting for differences in population growth.
how much of the increase is related to cannabis is impossible without
researching every crime. But police reports, news stories, and arrest warrants
suggest a close link in many cases. For example, last September, police in
Longmont, Colorado, arrested Daniel Lopez for stabbing his brother Thomas to
death as a neighbor watched. Daniel Lopez had been diagnosed with schizophrenia
and was “self-medicating” with marijuana, according to an arrest affidavit.
In every state,
not just those where marijuana is legal, cases like Lopez’s are far more common
than either cannabis or mental illness advocates acknowledge. Cannabis is also
associated with a disturbing number of child deaths from abuse and neglect—many
more than alcohol, and more than cocaine, methamphetamines, and opioids
combined—according to reports from Texas, one of the few states to
provide detailed information on drug use by perpetrators.
rarely receive more than local attention. Psychosis-induced violence takes
particularly ugly forms and is frequently directed at helpless family members.
The elite national media prefers to ignore the crimes as tabloid fodder. Even
police departments, which see this violence up close, have been slow to
recognize the trend, in part because the epidemic of opioid overdose deaths has
So the black tide
of psychosis and the red tide of violence are rising steadily, almost
unnoticed, on a slow green wave.
people worldwide have understood that cannabis causes mental illness and
violence—just as they’ve known that opiates cause addiction and overdose.
Hard data on the relationship between marijuana and madness dates back 150
years, to British asylum registers in India. Yet 20 years ago, the United
States moved to encourage wider use of cannabis and opiates.
In both cases, we
decided we could outsmart these drugs—that we could have their benefits
without their costs. And in both cases we were wrong. Opiates are riskier, and
the overdose deaths they cause a more imminent crisis, so we have focused on
those. But soon enough the mental illness and violence that follow cannabis use
will also be too widespread to ignore.
Whether to use
cannabis, or any drug, is a personal decision. Whether cannabis should be legal
is a political issue. But its precise legal status is far less important than
making sure that anyone who uses it is aware of its risks.
smokers don’t die of lung cancer. But we have made it widely known that
cigarettes cause cancer, full stop. Most people who drink and drive don’t have
fatal accidents. But we have highlighted the cases of those who do.
We need equally
unambiguous and well-funded advertising campaigns on the risks of cannabis.
Instead, we are now in the worst of all worlds. Marijuana is legal in some
states, illegal in others, dangerously potent, and sold without warnings
But before we can
do anything, we—especially cannabis advocates and those in the elite
media who have for too long credulously accepted their claims—need to
come to terms with the truth about the science on marijuana. That adjustment
may be painful. But the alternative is far worse, as the patients at Mid-Hudson
Forensic Psychiatric Institute—and their victims—know.