Why stronger cannabis might be raising risk of psychosis
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THC potency in cannabis has increased about fivefold over the past two decades, contributing to greater mental health risks for young, frequent users.
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Emergency visits for cannabis use or cannabis-induced psychosis in Ontario were linked to dramatically heightened odds of developing schizophrenia-spectrum disorders.
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Stopping cannabis and receiving treatment including medication and behavioral support can reduce the risk of ongoing symptoms and relapse.
Cannabis has changed a lot over the past 20 years especially in how strong it is.
In the early 2000s, dried cannabis in Canada usually had around 4% THC; now, most legal dried cannabis measures closer to 20%. Thats a fivefold increase in potency.
A new study is highlighting that todays cannabis isnt the same as what people used years ago and that change may explain why were seeing stronger links to serious mental health issues such as psychosis and schizophrenia.
Cannabis from the 2000s is not the same as in 2025, coauthor Nicholas Fabiano, M.D., said in a news release. THC content has increased by 5 times. This is likely a significant driver in the increasing link between cannabis use and schizophrenia.
The study
The researchers combed through records from Ontario, looking at nearly 9.8 million people who visited emergency departments.
They specifically compared the risk of later developing a schizophrenia-spectrum disorder for those who came in for cannabis use versus those who had cannabis-induced psychosis.
The results
The team found that those who visited the emergency department even just for cannabis use had a 14.3-times higher chance of being diagnosed with a schizophrenia-spectrum disorder later on.
Even more striking, those whose visit was due to cannabis-induced psychosis had a staggering 241.6-times higher risk.
The study also highlights that continuing to use cannabis after a first episode of cannabis-induced psychosis can make it more likely that symptoms will return.
The good news? Stopping cannabis use and, when needed, using antipsychotic medications, can help especially for those experiencing prolonged symptoms. On top of that, behavioral therapies like motivational interviewing or cognitive behavioral therapy can support people in quitting and sticking with treatment.
Posted: 2025-08-25 20:24:49