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The cannabis plant is perplexing. Currently, there is not enough high-quality research to determine just how the herb impacts the brain. Much of the available research has produced mixed results. Though, it’s clear that the connection between cannabis and psychosis warrants further investigation all around. But, does cannabis cause psychosis? Here’s a quick look at some recent studies.

Does cannabis cause psychosis?

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Unfortunately, there is no easy answer to this question. Research on the subject has been inconclusive. What information is available, however, suggests that psychosis far from a common cannabis side effect.

Thus far, the two most well-known risk factors for cannabis-induced psychosis are chronic teen cannabis consumption and familial predisposition for psychotic disorders.

In psychosis, patients experience delusions, hallucinations, and demonstrate unusual or erratic behavior. The patient cannot separate these delusions from reality. Psychotic disorders are seen in 1 percent of the population, of which an estimated 28.6 percent are considered heavy cannabis consumers.

Of those consumers, it is unknown how many began consuming prior or after the onset of symptoms. Further, based on these numbers, experiencing psychotic symptoms from cannabis would be very rare.

Additional research contests the negative connection between the two. Some phase II clinical trials even suggest that a nonpsychoactive cannabis compound, cannabidiol (CBD) holds potential as an adjunctive medication in treatment-resistant schizophrenia and psychotic disorders (more below).

These findings suggest that there is a lot more to the cannabis and mental health puzzle than meets the eye.

Many new cannabis consumers are concerned about cannabis and psychosis thanks to two of the herb’s most notorious side effects: anxiety and paranoia.

However, there is one major problem with much of the investigations into cannabis and mental health ailments. Various studies have shown a correlation between teen cannabis use and psychosis.

But, are these individuals consuming more cannabis because they have a prior mental health condition, or is cannabis the cause of these troubles? Correlation does not always mean causation.

Theories and research trends

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Overall, there are a few central trends floating around in the literature on cannabis and psychosis. To paint a picture of the current theories on the subject, below are four leading ideas on cannabis and psychosis.

Filled with pros and cons, the investigations leave much to be desired. However, the majority of these studies focus on the two predominant risk factors: chronic cannabis consumption in the teen years and familial heritage.

1. The correlative research

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A British case-control study published in Lancet Psychiatry in 2015 suggests that there is a connection between cannabis consumption and psychosis.

The study compared data from 410 cannabis consumers all of whom had experienced their first episode of psychosis, to 370 controls. During recruiting, controls were excluded if they had a previous history of psychotic disorders.

Those who had consumed high-potency, “skunk” cannabis daily were three times more likely to have experienced a psychotic episode. The researchers suggest that the increase in cannabis potency lead to more of a correlation between the two than in earlier studies.

However, this study cannot determine whether or not cannabis was the cause of the psychotic episode. The researchers acknowledge this issue in their paper, writing,

A theoretical explanation of why skunk might have been preferred by patients with first-episode psychosis is that, when they began to experience their illness prodrome, these individuals might have sought increased concentrations of THC to self-medicate.

Simply said, patients turn to high potency bud to control symptoms on their own. The study authors are also skeptical about why patients would gravitate toward a high THC strain to ease symptoms. THC, short for tetrahydrocannabinol, is the primary psychoactive component of the cannabis plant.

In experimental research, the researchers explain, THC has been found to increase psychotic symptoms. They continue,

That people who already have prodromal symptoms [early symptoms of psychosis] would choose a type of cannabis that is high in THC and has little cannabidiol (such as skunk), which might exacerbate their symptoms, rather than a cannabidiol-containing type (such as hash), would seem counterintuitive.

While counterintuitive, there are still a number of factors to consider in this issue. High potency cannabis is less expensive than hash. In the West, hash is also considered more of a luxury item than “skunk” cannabis bud. Further, for decades, there has been little education available about the therapeutic uses of different cannabis strains and products.

2. The no-correlation research

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Here’s where things become more complicated. Another 2015 study published in the journal Psychology of Addictive Behaviors found no clear link between cannabis use and the onset of psychosis in teen consumers. These results shocked the researchers themselves, as previous publications have suggested some sort of link.

To arrive at these results, the researchers from the University of Pittsburgh Medical Center and Rutgers University tracked 408 males from adolescence to the mid-30s. The study found that of that population, chronic teenage cannabis use was not associated with the following conditions:

In a press release, Jordan Bechtold, Ph.D. and psychology research fellow at the University of Pittsburgh Medical Center, explains,

There were no differences in any of the mental or physical health outcomes that we measured regardless of the amount or frequency of marijuana used during adolescence.

This study stirred some controversy. As reported by NPR, there were false claims made that the original study contained statistical errors. Another research group analyzed the study data to confirm the shocking results.

This second team found that cannabis consumption was associated with a slight increase in the risk of psychotic disorders in teen boys that used cannabis frequently. Five percent of frequent cannabis users met the criteria for psychotic disorders, compared to two percent of infrequent or nonconsumers.

This difference was not deemed statistically significant enough to show any sort of a link.

An earlier Harvard study published in 2014 evidenced that teen cannabis consumption is not lead to the development of schizophrenia later in life. The study compared families with a history of schizophrenia to those without. The study also examined non-psychotic cannabis consumers and non-consuming participant controls.

Researchers recruited 282 study participants. From these participants, the team received information on the mental health and drug abuse status of 1,168 first-degree relatives and 4,291 relatives total. After crunching the numbers, the team concluded,

The results of the current study suggest that having an increased familial morbid risk for schizophrenia may be the underlying basis for schizophrenia in cannabis users and not cannabis use by itself.

In this case, cannabis use did not seem to be an exact predictor of schizophrenia. Rather, a family heritage of mental health concerns seems to set the tone for the disorder.

The gene theory

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Interestingly, some people may be genetically more likely to experience cannabis-related psychosis. Research conducted in early 2016 found that mutations in a certain gene, AKT1, could possibly predict who is at risk for developing psychotic symptoms after consuming cannabis.

Scientists observed 442 consumers after using cannabis and while sober. They then measured memory loss and the symptoms of intoxication. The study found that those with AKTI gene mutations were more likely to experience paranoia, visual distortions, anxiety, and psychotic-like symptoms while high.

Even more shocking, large-scale study suggests that patients with schizophrenia may be genetically more prone to like cannabis. The study was published in Molecular Psychiatry and sampled data from 2,082 healthy participants and 1,011 cannabis consumers.

Researchers found a genetic association between the presence genes implicated in the risk of schizophrenia and cannabis use. In other words, those who are genetically predisposed to schizophrenia are also more likely to consume cannabis.

Additional research adds to this theory. Findings published in January of 2017, found that mutations in the gene BDNF Val66Met may play a role in the age of onset of psychotic symptoms after cannabis use. The study collected data from 260 Caucasian patients who had experienced their first psychotic episode.

Of these patients, the gene mutation and early cannabis use together were associated with an earlier age of onset for psychotic symptoms.

The stressor theory

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While there is solid evidence that genes, cannabis, and schizophrenia go hand-in-hand, some leaders in the field suggest that it’s possible that the herb may be just a little too stressful for some consumers.

Dr. Lester Grinspoon, psychiatrist, Harvard Professor Emeritus, and renowned cannabis and schizophrenia researcher thinks it is unlikely that cannabis causes psychosis. Though, he admits that it’s possible that the psychoactive effects of the herb could be stressful enough to trigger psychosis in some people.

However, when asked by Mint Press News about whether cannabis causes psychosis, Grinspoon mentions that he has never, in his lifetime as a psychiatrist, seen something of the sort. He says that cannabis can cause paranoia and anxiety, which can make novice consumers uncomfortable. He explains,

That’s why people have to learn smoking it. I can imagine that with someone who is cannabis naive and has that kind of experience it can occur as a precipitating event. Many schizophrenics say their psychotic episode started after such a precipitating event.

Those events can range from an automobile accident or the death of a loved one. And I can imagine, I have never seen this, that the naive use of marijuana can act as a precipitating event.

One anecdotal example, however, perhaps gives some credence to the fact that cannabis may trigger some strong reactions in people. In an interview with Vice News, Devan Fuentes explained,

I had a big delusion that I was figuring something out that no one understood but me that would eventually save the world. The day of my psychosis, I charted everything out and put it on a piece of paper after I had just smoked a ton of weed.

Fuentes was diagnosed with a schizoaffective disorder, which is sort of a mysterious mix of a psychotic and mood disorder. Whether the cannabis was the cause or a stressful trigger, in this case, is unclear. However, it seems like some people are simply better off without psychoactive cannabis.

Some research even suggests that early cannabis use may cause symptoms of schizophrenia to begin up to three years early in those who are predisposed to the condition.

Does cannabis help psychosis?

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While it may seem counterintuitive, nonpsychoactive cannabis may one day prove helpful for those with psychotic disorders. In 2015, a British pharmaceutical company, GW Pharmaceuticals, announced successful phase 2 clinical trials of cannabidiol (CBD) in treatment-resistant schizophrenia. The CBD was derived from the cannabis plant.

CBD is one of the most common cannabinoids, active compounds, in the cannabis plant. Unlike THC, cannabidiol does not cause cognitive distortions. The compound is completely nonpsychoactive, and may even reduce some of the negative psychoactive effects of THC.

In the trial, 88 schizophrenia patients with treatment-resistant symptoms were given either CBD or a placebo. The trial found that CBD was not only successful against the placebo but was well-tolerated and produced minimal side effects.

Patients showed improvement in both the positive and negative symptoms of schizophrenia. Positive symptoms include agitation, paranoia, and hallucinations. Negative symptoms include depression and apathy.

High-CBD strains or products are available to patients in medical cannabis states. Recreational cannabis shops also typically carry a selection of CBD strains. Some common high-CBD strains include:

So, what is the final verdict after all of that research? There certainly seems to be some connection between cannabis use and psychotic disorders. However, the relationship is much more complex than ever expected. Medical researchers and public health officials will be crunching on this one for a while.

Based on the findings thus far, young people should avoid hitting the green too hard, if at all.

For more information on cannabis and mental heath, check out the article here.

The information in this article is meant for helpful and educational purposes and should not be used in place of medical advice or treatment. Always contact a health care provider in the event of a mental health emergency. 

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