Marijuana may trigger mental illness in users who possess a particular gene.
According to Medical Daily, the relatively small number of marijuana users who develop psychosis often have a variant of a gene called AKT1.
Previous research found approximately 1 percent of marijuana users develop psychosis, and many of them have this particular gene variant, Daily Mail reports.
Researchers from the University of Exeter and University College of London enlisted 442 marijuana users aged 16 to 23 for a study that looked more closely at the presence of AKT1 and its effects on those who smoke weed.
Out of these participants, 49 percent had a certain variation of AKT1, which is linked to psychosis, but had no health problems.
Participants underwent tests before and after using marijuana to see how their cognitive abilities were affected.
Compared to marijuana users without the AKT1 variation, the group with the gene displayed more psychotic symptoms such as hallucination and paranoia after smoking.
Celia Morgan, a professor of psychopharmacology at the University of Exeter, reportedly said,
These findings are the first to demonstrate that people with this AKT1 genotype are far more likely to experience strong effects from smoking cannabis, even if they are otherwise healthy. To find that having this gene variant means that you are more prone to mind-altering effects of cannabis when you don't have psychosis gives us a clue as to how it increases risk in healthy people.
Morgan suggested marijuana users who go on to develop psychosis may not have done so had they not used marijuana.
The researchers also learned female marijuana users were more likely to experience short-term memory impairment from smoking marijuana than male users.
This finding supports previous studies conducted on animals, which found males possess more cannabinoid receptors in areas of the brain associated with short-term memory.
While this is the first study to conclude a certain gene variant may cause specific marijuana-induced mind alterations, the researchers noted more studies are needed to see if other gene variants are factors as well.
These results may be an important first step, however, in developing drugs designed to treat those who develop psychosis as a results of smoking marijuana.
It's probably best to stay away from marijuana if it leads to paranoia and hallucinations, even if the latter seems like the foundation for a chart-topping rock album.
This study was originally published in the journal Translational Psychiatry.
Citations: The gene that puts cannabis users at risk of psychosis: Scientists discover why some smokers are more prone to mental illness (Daily Mail), A Gene For Psychosis? This Allele Predicts How Susceptible You Are To The Mind-Altering Effects Of Weed (Medical Daily), Gene could help identify psychosis risk in cannabis users (EurekAlert!)