Daily Use of High Potency Marijuana Linked to Psychosis

Daily Use of High Potency Marijuana Linked to Psychosis March 20, 2019

As more states legalize the recreational use of marijuana, more adults are using high potency strains of the plant.  A new study published in the Lancet determined that daily users of potency marijuana are five times more likely to develop psychosis than non-smokers.

America has been rolling back the prohibition of marijuana for nearly a decade. According to Leafy, eleven states permit the recreational use of the plant. In nineteen states, people can use pot for medicinal purposes.

As more people indulge in the herbal delight, researchers work to identify adverse side-effects of the drug. The study looked at individuals aged 18-64 — these people presented in psychiatric services across 11 sights in Europe and Brazil with first episode psychosis. The study was controlled by recruiting representatives that were representative of the local population.

In the findings, daily users were three times more likely to develop psychosis than non-users. Most concerning is that users of high potency marijuana were five times more likely to develop psychosis than their healthy peers.

For instance, in Amsterdam, where heavy use of high potency marijuana is common, daily users of the drug were nine times more likely to develop psychosis.

In London, heavy smokers were five times more likely to develop psychosis. For all new psychosis diagnosis in these cities, 30-50% of patients smoked high potency marijuana.

By eliminating access to the highest potency marijuana, researchers believe that first-episode psychosis diagnoses could drop considerably.

In the study’s conclusion, the authors wrote,

“Our findings confirm previous evidence of the harmful effect on mental health of daily use of cannabis, especially of high-potency types. Importantly, they indicate for the first time how cannabis use affects the incidence of psychotic disorder.

Therefore, it is of public health importance to acknowledge alongside the potential medicinal properties of some cannabis constituents the potential adverse effects that are associated with daily cannabis use, especially of high-potency varieties.”

To support their findings, researchers found other studies that support their conclusion that high potency marijuana increases the risk of psychosis. Three other studies found in Pub Med also linked the drug to psychosis. With the current research being the largest to date, containing over 900 people, this is the first time researchers have linked marijuana to psychosis.

Advocates of marijuana consistently downplay that the plant can cause any negative side effects. However, scientific data is beginning to debunk the myth that the drug is harmless. Even though psychosis remains a rare adverse reaction, we should not ignore the potential long term mental health issues from daily consumption.

Perhaps the study can serve as a good reminder to users that moderation of the drug is key. Finally, if you must smoke, try to find weaker strains of the plant to reduce your risk.


*Katie Joy is a columnist and hosts Without A Crystal Ball on Patheos Non-Religious Channel. She writes articles on parenting, disability advocacy, debunking pseudoscience, atheism, and crimes against women and children.

She co-hosts the YouTube show, “The Smoking Nun,” with Kyle Curtis. The show airs weekly and tackles pseudoscience, current events, and crime stories.

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What Are Your Thoughts?leave a comment
  • otrame

    Never thought it was harmless. Daily consumption of the really strong stuff causes problems? So does daily consumption of really strong alcohol. Alcohol is legal. And so should marijuana.

  • Michelle Sarabia

    I suspect that these are people who are already dealing with psychosis, are using weed to self-medicate the related anxiety, and then are so relaxed they no longer feel inhibited expressing their perceptions.

  • Raging Bee

    Sounds like wishful thinking to me. I’m all in favor of legalized weed, but we need to be honest about its effects.

  • Michelle Sarabia

    I would want to see the study to see if they took this possible confounding variable into consideration… most mental health issues are based on self-report, including pyschosis. Mild psychosis can be easily concealed.

  • Knitting Cat Lady

    From what I understand the younger you are, the higher the risk of psychosis.

    That mind altering substances have long term negative side effects falls into ‘well duh’ territory for me.

    I think many people trip into the naturalistic fallacy. Weed is ‘natural’ so it’s harmless. Destroying angels, hemlock, and getting mauled by a tiger are natural as well.

    I’m all for legalizing weed, as long as it comes with the same restrictions and warnings as tobacco.

    Actually, I’m for the legalization of ALL recreational drugs. Proper quality control and less cutting with who knows what would be a huge health benefit for addicts.

    And getting rid of the war on drugs would get rid of a ton of crime.

  • Lisa Cybergirl

    Apparently it can trigger onset of schizophrenia, although it’s unknown if the person would have developed schizophrenia anyway later on.

  • Powerglide

    You know what else has been found in studies to ‘trigger’ psychosis? Meditation. This is merely a correlational study that says nada about causation.

  • mr_bandit

    i have doubts about this study. The brain has THC receptors. Once they are saturated, you don’t get more stoned. (Think of water and a bucket.) The “high potency” should just mean you don’t need as much to saturate. I want to see more studies. I also want to know who paid for the research.

    It could also be that those who are more susceptible to psychosis, now that pot is becoming legal, is these folks are spending time trying to self-medicate, but the level of THC from heavy smoking tips them over the edge.

    Of course, pot kills creativity and the work ethic. It’s the drug-of-choice of engineers in Silicon Valley, and they have not produced anything to speak of….

    This also begs the question of why the brain has THC receptors.