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Higher than ever: New study links strong weed to psychosis

Derek Maiolo / Steamboat Pilot
A recent study linked highly potent weed with psychosis. This comes as more states are moving to legalize marijuana for both medical and recreational purposes.
Stock photo/Shutterstock

STEAMBOAT SPRINGS — If someone could time-travel back to a 1970s Woodstock festival and pass around a joint stuffed with top-shelf, Colorado-grown marijuana, the effects could shatter people’s reality.

That’s because today’s marijuana strains, following a wave of legalization and prolific cultivation, can be more than three times as potent as strains from even a decade ago.

While weed enthusiasts and growers see this as a sign of legalization’s success, an increasing number of studies raise concerns about the side effects of more potent strains.



With cannabis now legal in some form in all but 17 states, the plant has gained greater acceptance and even an aura of healthfulness as people use it to treat ailments like chronic pain or anxiety.

But one of the most recent studies of marijuana use — published Tuesday in “The Lancet Psychiatry” — showed consuming high-potency products increased the risk of having a psychotic episode later.



The plant’s effects have become truly reality shattering, but not in a good way.

More potent, more common

A trip to any local marijuana dispensary proves just how far marijuana has come in recent years.

On Wednesday, the menu at Golden Leaf, one of the three dispensaries in Steamboat Springs, offered two top-tier flower strains with THC contents of 30 percent. Tetrahydrocannabinol, or THC, is the cannabinoid in marijuana that gets people high.

Road Dawg, a sleep-inducing Indica, was going for $20 for a gram alongside a hybrid, Cookies X, which clocked in at 30.2 percent THC.

THC content skyrocketed for the available concentrates, a much more potent form of weed that requires processing in a lab.

Double Dream, a toffee-looking concentrate called “shatter,” cost just $25 for a gram and contained 87.8 percent THC.

That is a huge spike from even a decade ago, and the upward trend is not unique to Colorado. A recent study found the average potency of weed in Europe and the U.S. was 17.1 percent in 2017, up from 8.9 percent in 2008.

Golden Leaf Anderson, the dispensary’s owner, explained legalization has given growers free reign to develop ever-stronger products that customers are willing to pay top dollar for.

“It can reach as high as 33 percent,” he said.

In the study linking stronger potency to psychotic breaks, researchers analyzed 901 patients with first-episode psychosis across 11 European cities. They also analyzed a control group composed of 1,237 people from the same cities that have not been diagnosed with psychosis.

For both, the study’s authors asked the subjects about their habits, including their use of weed. They also asked users the names of the strains they typically consumed, which allowed them to find the THC content of each using the European Monitoring Center for Drugs and Drug Addiction.

Researchers found using high-potency marijuana, which they defined as strains with more than 10 percent THC, more than doubled the chances that users would experience a psychotic episode compared to someone who had never used weed.

The risk increased for people who smoked high-potency weed on a daily basis. Those people were more than four times as likely to experience a psychotic episode compared to someone who had never used it.

Perhaps the most novel of the study’s findings is its correlation between cities with the most potent strains and those with the highest incidence of psychotic episodes.

The three European cities — London, Paris and Amsterdam — with the highest rates of new diagnoses of psychosis were also the cities where high-potency weed is most readily available and commonly used.

Cities that offer more products with THC content below 10 percent had lower rates of new diagnoses, according to the study.

These findings are consistent with previous studies linking marijuana use to higher risk of psychosis.

Skeptical scientists

Other scientists, upon reading the results of such studies, are quick to mention that correlation does not imply causation.

Dr. William Kurr is the director of the Alcohol Research Group, but he has recently looked into changing attitudes of marijuana use as more states legalize it.

He explained the plant’s decades-long prohibition has made it impossible to conduct accurate research that could show a definitive link between marijuana use and psychosis. That would require following people over many years, from before they started using to when, and if, they had a psychotic break.

“You can’t only rely on people to disclose their behavior about using it,” he said, referring to the methodology of the above study.

Researchers also would need to consider genetic predisposition to psychosis, among a list of other potential factors.

“Not to say that all these claims are untrue, and there aren’t any harms, but there is not enough proof of those harms to show that we need to ban (marijuana,)” Kurr said.

Rather than its effects, Kurr has been more interested by the broadening acceptance of marijuana use.

“Even if people are less likely to use it themselves, they are more accepting of others using it,” he said.

Educating the public

Golden Leaf Anderson has noticed a similar trend among his customers. He often sees tourists come in from states without legal cannabis who want to try it for the first time or older people who smoked when they were younger and want to test the new and improved products.

Anderson is well aware that more potent strains can induce negative side effects, namely anxiety, if people are not regular users. That is why he trains all of his employees to talk through the different products with customers and ensure that they understand what they are buying.

“We want everyone to have a good experience,” he said.  “We don’t want them dosing too high because then they won’t have a good experience.”

But for some people, especially those with medical conditions, stronger strains offer them the high they need, Anderson added.

“Some people need higher doses to help with pain or certain issues,” he said.

It could take decades before scientists come to any kind of definitive consensus about the potential dangers of marijuana use. Until then, growers will continue to give the public what they want. For many, that means high potency strains.

For others, they want a more balanced ratio of THC with its non-psychoactive counterpart, CBD. Those tend to have lower THC contents in the teens.

“It’s just like liquor,” Anderson said. “Some people want Everclear and some people want Budweiser.”

To reach Derek Maiolo, call 970-871-4247, email dmaiolo@SteamboatPilot.com or follow him on Twitter @derek_maiolo.


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