Menus Subscribe Search

Follow us


The Marijuana and Schizophrenia Conundrum

• March 01, 2010 • 3:36 PM

There’s a connection between marijuana and schizophrenia, and as scholars tease out the chicken-and-egg genetic aspect, they counsel teen tokers to take heed.

For years it’s been a classic chicken-or-egg riddle: Does smoking marijuana lead to schizophrenia, or are those with schizophrenia who use cannabis simply seeking the calming effects of the drug?

Researchers have suspected a link since the 1960s, and study after study has hinted that use of marijuana may trigger schizophrenia, a serious mental illness that affects one in 100 people.

Recent studies, however, provide evidence strong enough to give public health officials — not to mention parents and educators — pause, especially as legalization efforts pick up steam. The latest to weigh in is research to appear in the May issue of the Archives of General Psychiatry. Scientists in Australia followed nearly 4,000 young adults born between 1981 and 1984 at the 21-year mark, and found that the longer study participants had used marijuana, the higher the risk of psychosis-related outcomes. Those who had experienced hallucinations early were more likely to have smoked or used marijuana longer and more frequently.

The study’s authors said there is significant complexity in the relationship: Essentially, those who were vulnerable to psychosis were more likely to use cannabis, which in turn could contribute to an increased risk of developing mental illness.

“The research is conflicting, but the preponderance of the evidence shows that something is there,” said Ken Duckworth, the medical director of the National Alliance on Mental Illness.

If you are a teenager and you smoke marijuana, you put yourself at risk, he said, especially if you have the gene or genes suspected of predisposing one to schizophrenia.

Marijuana is the most used, and abused, illicit drug in the United States, with more than 4.2 million people over the age of 12 reporting substance abuse or dependence in 2008. That is more than twice the number of people who abuse or are dependent on pain relievers, (1.7 million) and cocaine, (1.4 million), the second and third most widely abused drugs in this country.

It is also the most widely used drug among those who have been diagnosed with schizophrenia. In the early 1970s, there was speculation cannabis helped dim the voices and other hallucinations typical with schizophrenia. But researchers started to look at it from the other direction, surmising that marijuana use, particularly heavy marijuana use, may contribute to the onset of schizophrenia symptoms.

In a large study reported in 1987, cannabis use in late adolescence was associated with an increased risk of a subsequent diagnosis of schizophrenia. Studies over the past five years have pinpointed direct connections between brain abnormalities and THC (tetrahydrolcannabinol), the primary psychoactive ingredient in marijuana.

In 2005, researchers at New York’s Albert Einstein College of Medicine used a brain imaging technique called diffusion tensor imaging to study the brains of groups of adolescents for a year. They included healthy non-drug users, heavy marijuana users (daily use for at least a year) and schizophrenic patients. They found that repeated exposure to cannabis resulted in abnormalities in a critical fiber pathway in the brain related to higher aspects of language and auditory functions.

Two years later, in 2007, scientists at Cardiff University’s School of Medicine in Wales found that regular cannabis use among young people increased their risk of developing a psychotic illness later in life by more than 40 percent. And the more they smoked marijuana, the higher the risk. Those who smoked most frequently were more than twice as likely to develop psychosis. Similar results were uncovered by Spanish researchers.

American researchers confirmed those findings in 2009. Emory University doctors reported that teenagers who progressed to daily marijuana consumption experienced psychotic and pre-psychotic symptoms of schizophrenia at earlier ages.

Scientists have known for years that schizophrenia runs in families. Now scientists can point to specific genes, including dysbindin-1, which affects glutamate synaptic function in the hippocampal function area of the brain. The genes neuregulin 1, G72, D-amino acid oxidase, and regulator of G protein signaling 4, or RGS4, have also been implicated.

David A. Lewis, director of the Translational Neuroscience Program at the University of Pittsburgh School of Medicine, and his research team were one of several groups to identify the RGS4 gene in studies of the prefrontal cortex as susceptible for schizophrenia.

In subsequent research Lewis and his colleagues found that gamma-aminobutyric acid, which is an important neurotransmitter required for cognitive processes such as working memory, is impaired by the cannabinoid 1 receptor, which is where THC is activated. In simpler terms, marijuana use impairs the brain’s ability to perform intellectual tasks.

Both of these findings suggest a prefrontal cortex disruption that affects working memory, which is deficient in individuals with schizophrenia, according to Lewis. He hopes further study will ultimately result in drug therapies that will replace the loss of gamma-aminobutyric acid in schizophrenic patients and reduce hallucinations and other symptoms.

But here’s the thing, NAMI’s Duckworth said, once you develop symptoms of the disease, there’s no going back. So why toss the dice by using marijuana?

“It’s quite a chance to take. The uncertainty in the scientific knowledge should not be confused with the risk,” Duckworth said.

Schizophrenia, characterized by serious hallucinations and delusions, is estimated to be the fourth most important cause of life-years lost through disability in the world. And it is irreversible, Duckworth said.

If marijuana consumption continues after a diagnosis, drug addiction is coupled with mental illness and is known in the mental health community as dual diagnosis.

Duckworth said the system is ill-prepared to deal with mentally ill people who are also drug abusers. The mental health system doesn’t know how (or doesn’t want) to treat the drug problem, and the substance abuse health system is ill-equipped to help the mentally ill. Duckworth said he has patients who have been told at drug counseling meetings to go off their psychiatric medications.

“Policymakers are realizing more and more that the [treatment] silos need to be blended,” Duckworth said. But funding comes from varying places, and so coordination is difficult. Sadly, it is the patients who suffer more.

“The dually diagnosed have the worst outcomes,” Duckworth said. They spend the most time in jail, they are the heaviest users of public health and social welfare services, and they die younger than any other cohort, he said.

Sign up for our free e-newsletter.

Are you on Facebook? Become our fan.

Follow us on Twitter.

Add our news to your site.

When it comes to marijuana use, his advice to teens and parents is simply: Don’t chance it.

Marcia Meier
Marcia Meier is an author and teacher who has written for numerous publications, including the Los Angeles Times, Santa Barbara Magazine, Central Coast Magazine, OC Metro magazine, the Seattle Times and Arizona Republic. She is also an occasional blogger with The Huffington Post. Her latest book, Navigating the Rough Waters of Today's Publishing World, Critical Advice for Writers from Industry Insiders, will be out in June 2010.

More From Marcia Meier

A weekly roundup of the best of Pacific Standard and PSmag.com, delivered straight to your inbox.

Recent Posts

October 21 • 4:00 AM

She’s Cheating on Him, You Can Tell Just by Watching Them

New research suggests telltale signs of infidelity emerge even in a three- to five-minute video.


October 21 • 2:00 AM

Cheating Demographic Doom: Pittsburgh Exceptionalism and Japan’s Surprising Economic Resilience

Don’t judge a metro or a nation-state by its population numbers.


October 20 • 4:00 PM

The Bird Hat Craze That Sparked a Preservation Movement

How a fashion statement at the turn of the 19th century led to the creation of the first Audubon societies.


October 20 • 2:00 PM

The Risk of Getting Killed by the Police If You Are White, and If You Are Black

An analysis of killings by police shows outsize risk for young black males.


October 20 • 12:00 PM

Love and Hate in Israel and Palestine

Psychologists find that parties to a conflict think they’re motivated by love while their enemies are motivated by hate.


October 20 • 11:00 AM

My Dog Comes First: The Importance of Pets to Homeless Youth

Dogs and cats have both advantages and disadvantages for street-involved youth.


October 20 • 10:00 AM

Homophobia Is Not a Thing of the Past

Despite growing support for LGBT rights and recent decisions from the Supreme Court regarding the legality of same-sex marriage, the battle for acceptance has not yet been decided.


October 20 • 8:00 AM

Big Boobs Matter Most

Medical mnemonics are often scandalous and sexist, but they help the student to both remember important facts and cope with challenging new experiences.


October 20 • 6:00 AM

When Disease Becomes Political: The Likely Electoral Fallout From Ebola

Will voters blame President Obama—and punish Democrats in the upcoming mid-term elections—for a climate of fear?


October 20 • 4:00 AM

Coming Soon: The Anatomy of Ignorance


October 17 • 4:00 PM

What All Military Families Need to Know About High-Cost Lenders

Lessons from over a year on the beat.


October 17 • 2:00 PM

The Majority of Languages Do Not Have Gendered Pronouns

A world without “he.” Or “she.”


October 17 • 11:01 AM

How to Water a Farm in Sandy Ground

Physicists investigate how to grow food more efficiently in fine-grained soil.


October 17 • 10:00 AM

Can Science Fiction Spur Science Innovation?

Without proper funding, the answer might not even matter.


October 17 • 8:00 AM

Seattle, the Incredible Shrinking City

Seattle is leading the way in the micro-housing movement as an affordable alternative to high-cost city living.


October 17 • 6:00 AM

‘Voodoo Death’ and How the Mind Harms the Body

Can an intense belief that you’re about to die actually kill you? Researchers are learning more about “voodoo death” and how it isn’t limited to superstitious, foreign cultures.


October 17 • 4:00 AM

That Arts Degree Is Paying Off

A survey of people who have earned degrees in the arts find they are doing relatively well, although their education didn’t provide much guidance on managing a career.


October 16 • 4:00 PM

How (Some) Economists Are Like Doomsday Cult Members

Cognitive dissonance and clinging to paradigms even in the face of accumulated anomalous facts.


October 16 • 2:00 PM

The Latest—and Most Mysterious—Player in the Nasty Battle Over Net Neutrality

As the FCC considers how to regulate Internet providers, the telecom industry’s stealth campaign for hearts and minds encompasses everything from art installations to LOLcats.


October 16 • 12:00 PM

How Many Ads Is Too Many Ads?

The conundrum of online video advertising.


October 16 • 11:00 AM

Unlocking Consciousness

A study of vegetative patients closes in on the nature of consciousness.


October 16 • 10:00 AM

The False Promises of Higher Education

Danielle Henderson spent six years and $60,000 on college and beyond. The effects of that education? Not as advertised.


October 16 • 8:00 AM

Faster Justice, Closer to Home: The Power of Community Courts

Community courts across the country are fighting judicial backlog and lowering re-arrest rates.


October 16 • 6:00 AM

Killing Your Husband to Save Yourself

Without proper legal instruments, women with abusive partners are often forced to make a difficult choice: kill or be killed.


October 16 • 4:00 AM

Personality Traits Linked to Specific Diseases

New research finds neurotic people are more likely to suffer a serious health problem.


Follow us


Love and Hate in Israel and Palestine

Psychologists find that parties to a conflict think they're motivated by love while their enemies are motivated by hate.

How to Water a Farm in Sandy Ground

Physicists investigate how to grow food more efficiently in fine-grained soil.

Unlocking Consciousness

A study of vegetative patients closes in on the nature of consciousness.

Advice for Emergency Alert Systems: Don’t Cry Wolf

A survey finds college students don't always take alerts seriously.

Brain’s Reward Center Does More Than Manage Rewards

Nucleus accumbens tracks many different connections in the world, a new rat study suggests.

The Big One

One company, Amazon, controls 67 percent of the e-book market in the United States—down from 90 percent five years ago. September/October 2014 new-big-one-5

Copyright © 2014 by Pacific Standard and The Miller-McCune Center for Research, Media, and Public Policy. All Rights Reserved.