British Study Links High THC Potency with Psychosis

9 months ago

Research into cannabis and its potential impact on psychosis keeps coming. Some days ago we reported about a study from the Kings College in London that CBD could have positive effects on psychosis.

This week, a new study coming from the same Kings College in London, and published in The Lancet psychiatric publication, claims that high potency THC cannabis may lead to higher chance on developing psychosis.


Of course, here at Alibi HQ we regularly refer to the stick that is psychosis when it comes to warning about the use of cannabis, yet we welcome all research no matter which outcome because we also want to get to understand the plant — and its effects — better. Especially when it comes to that psychosis topic.

The study’s lead author, Marta Di Forti, claims that the amount of used marijuana and the THC potency levels are important factors when it comes to linking cannabis consumption and psychosis.

The team analyzed the consumption habits of almost 1,000 patients in 11 sites in multiple countries, among which the Netherlands and the UK, highlighted that one psychosis patients in five smoked daily. Additionally, every tenth new case was linked to smoking marijuana with a THC level above 10 percent.

“We clearly showed that across the 11 study sites, those who use high potency on daily bases have over a 4 fold increase in the odds of having a psychotic disorder”
Marta Di Forti, lead author

Sadly enough, the study was like most other studies mostly observational, rather than based on true data and even worked with estimated “expected concentrations” of THC for localities, based on national data. As such the effects observed were greater in Amsterdam and London, where THC potency can generally be higher.

The study, upon publication, was quickly questioned by Suzanne Gage, Lecturer in Psychology at the University in Liverpool for lacking true causation evidence.

Gage claimed that while the analysing team had made the necessary efforts to observe, the study still was mostly observational and no hard link between THC and psychosis has been proven yet.

“There’s lots of this observational data that suggests this link, but it’s very definitively hard to say, ‘Yes, cannabis causes psychosis’”
“It’s definitely not the case that everyone who uses cannabis every day will develop psychosis, so it just makes the pattern quite complicated. People who choose to use high potency cannabis every single day are likely to be different from people who don’t in lots of ways other than just their cannabis use.”
Suzanne Gage, Ph.D Lecturer Psychology, University of London to Inverse.

Gage also pointed out that one of the things making analysis, and finding correlation, more difficult is the relatively low number of cases of psychosis.

Interestingly enough, the analysing team observed that when high CBD was consumed before THC then the effect was less and psychosis would usually not occur.

Hopefully soon most research team will receive access to legal marijuana to analyse, because obviously there is still lots of work to be done and our understanding of cannabis and its effects is still very limited.

Get 4.2 Free Smoke Power On Sign Up To Start Your Journey On Smoke! The First Cannabis Community That Pays You To Post And Curate Content You Love..
Sort Order:  Trending

The main problem that I don't see specifically addressed here is the idea that it's possible that people prone to psychosis happen to also smoke pot.

If I'm in a mental state that isn't comfortable, weed seems like a natural first step to try to self-medicate.

I think I've used the analogy of a burn ward before. If these people walk into a burn ward, would they say that pain medication leads to severe burns? "All the people we traced back on these pain medications had severe burns!"


The study mentioned that THC potent users were more prone to their first cases of THC. I generally do agree though that background and history before the study should also be highlighted more.

But maybe that would have totally changed the number of patients observed.

If anything we know this may/will lead to further research. Which is much needed.

So much fake News out there.


Aside from it being observational, I don’t think it’s “fake news” as such.

But it’s a game of risk assessment and also overexposure. Times have changed though, nowadays — despite growing world population — 5 deaths are 5 too many. In the past that would be considered negligible.

Obviously, I don’t like it because I think the constant focus contributes to FUD. But at the same time, it is positive because it will lead to further research and may lead to better understanding. Maybe even debunking.

Maybe some day we discover it’s specific components of Indicas and we can create Indica strains without those, thus eliminating the risk of Psychosis for those prone to it.