We've long known that pot can affect different people in various ways -- some smokers only experience a slight "buzz" while others can become paranoid or even hallucinate.
Now, a team of researchers in the U.K. has found a way to identify which cannabis users are more at risk of developing such strong reactions.
A variation of the gene called "AKT1" is linked to people being more susceptible to the mind-altering effects of cannabis than otherwise, according to a provocative new study published in the journal Translational Psychiatry on Tuesday.
While some previous studies suggest only around 1-5 percent of cannabis users end up developing psychosis, it's the AKT1 gene variant that may put those users more at risk, study lead author Dr. Celia Morgan, professor of psychopharmacology at England's University of Exeter, told The Huffington Post.
"We know relatively little about what makes certain people vulnerable to developing psychosis from smoking cannabis but this research suggests one piece in the puzzle might be this genetic difference," she said. "Cannabis and its extracts are being increasingly recognized for their medical uses so this is another reason why it is key to keep trying to find ways of predicting who will experience negative effects from its use."
For the study, the researchers tested 442 marijuana users for psychotic-like symptoms while they were high and then again about a week later when they were sober. The researchers measured the extent of the symptoms and effects on memory loss and compared results.
They found that the study participants with a certain variant of the AKT1 gene had a much stronger reaction to cannabis -- including symptoms like paranoia, magical thinking and visual distortions -- than their counterparts.
We were surprised to find more memory impairment in women. Study lead author Dr. Celia Morgan
The researchers also noticed that women were more likely to have a short-term memory impairment from cannabis.
"We were surprised to find more memory impairment in women," Morgan said. "The AKT1 finding was what one would predict from previous work that found that people who had psychosis from smoking cannabis were more likely to have this variant of the gene. So that was not so much of a surprise."
The researchers concluded that genetics must play a key role in the unusual link between cannabis and psychosis.
"Our finding that psychotic-like symptoms when young people are 'stoned' are predicted by AKT1 variants is an exciting breakthrough as this acute reaction is thought to be a marker of a person’s risk of developing psychosis from smoking the drug," said Dr. Valerie Curran, professor of psychopharmacology at University College London and a co-author of the study, in a statement.
The new study could be used to help develop a way to identify those at-risk cannabis-users, or possibly help in the development of drugs that might target the AKT1 gene variant, Morgan told HuffPost.
"There is definitely a link between smoking cannabis and psychosis although most people that smoke cannabis are very unlikely to develop psychosis," she said. "Much more work is needed to be able to fully profile risk in people and this is likely to be a large number of genes."
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