ello (@piers)

"Cannabis-users who develop psychosis in their 30s experience symptoms **more than six years earlier on average** than people with the condition who don't use the drug, according to new research. "These figures are in sharp contrast to younger age groups, with cannabis-users in their early 20s who develop psychosis doing so on average about 1.6 years earlier than non-users, and no evidence of earlier onset in those under 20. "The study's senior author, **University of New South Wales** (UNSW) researcher **Matthew Large**, said the association between using cannabis and the early onset of psychosis had already been suggested by previous studies. "But in this new large-scale analysis, **published today in Biological Psychiatry**, Dr Large said researchers were able to examine an **"enormous amount of data"** and use **"fine grain analysis"** to look at age sub-groups for the first time. "People experiencing psychosis often feel disconnected from reality, and struggle to distinguish between what's real and what isn't. "The older the age group was, Dr Large explained, the larger gap there was between cannabis-users and non-users in regards to the age when symptoms of psychosis first appeared. "*It was widely assumed that the earlier age of onset of [psychosis] mostly affected young people. This study shows, contrary to that expectation, that it mostly affects people in their late 20s and over 30s*," he said. "*That is a finding that has not been demonstrated in any other study, [it] hasn't even been suggested*." "**The study's lead author**, UNSW academic and medical student **Carly Stevens**, said this suggested the harm could be **"cumulative"**. "*There seems to be this predominant idea of the adolescent brain being very vulnerable, which is true*," she said. "Using cannabis at a young age can disrupt neurodevelopmental processes in the adolescent brain, influencing how the brain develops, affecting the memory, attention and growth. "*But also this prevailing myth that if you wait until your brain develops, and then you engage in these kind of behaviours, that you'll be OK*," she said. "*But our findings likely show that in terms of the onset of psychosis, it's not younger people that are at risk, but actually older people*." "Earlier in life, Ms Stevens said genetic vulnerability and neurodevelopmental factors could play a greater role as there was very little time for cannabis to have an influence. But, she said, ongoing cannabis use could lower the threshold for when symptoms of psychosis first appeared later in life. "Dr Large, who is a clinician and works directly with patients, said about 3% of people will experience psychosis at some point in their lives and 1% will develop schizophrenia, which is a lifelong condition. "A similar large-scale analysis led by Dr Large and published in 2011 probed 83 studies and **found the mean age of psychosis onset for cannabis-users was 2.7 years younger than non-users**. This new analysis, which looked at 149 international studies involving more than 71,000 people, **suggested the age of psychosis onset for cannabis-users was 2.5 years earlier**, on average. "**Dr Large said the similarities between the two suggested the overall conclusion was robust**. "**Jack Wilson**, a research fellow at The University of Sydney's Matilda Centre who did not contribute to the study, said it added to **"the growing body of evidence"** that cannabis use was associated with a greater risk of developing psychosis. "*It's certainly providing new evidence on the likelihood of developing psychotic disorders in different age groups, according to whether someone is using cannabis or not*," he said. "*And that is quite concerning, given the relative ease at which we can now access increasingly potent cannabis products in Australia*." "Dr Wilson said higher consumption of tetrahydrocannabinol or THC was **"associated with the greater risk of harm"**. "One of the study's limitations was that it didn't probe the type of cannabis products that were being used, Dr Wilson said, and extra information about potency would be useful to know [...]." Lauren Roberts, ABC #Cannabis #Psychosis https://www.abc.net.au/news/health/2026-08-19/cannabis-linked-to-earlier-onset-of-psychosis/107048934