"While there may still be questions about the nature of the link between daily use of high-potency marijuana and psychotic disorder, this study suggests that we should be monitoring this issue very closely and taking steps to protect the public's health".
Once adjusted for other factors, the authors found that across the 11 sites, people who used cannabis on a daily basis were three times more likely to have a diagnosis of first episode psychosis, compared with people who had never used cannabis.
Frequency of use was also highlighted by researchers: the chances of having a psychotic disorder were 40% greater among those who used the drug more than once a week compared with those who rarely, if ever, used it, while the chances of having a psychotic disorder were more than three times greater among those who used cannabis daily compared with those who rarely if ever used it.
Scientists looked at the drug use history of 901 patients who had experienced a psychotic episode, and 1,237 healthy individuals.
"The use of cannabis with a high concentration of THC has more harmful effects on mental health than the use of weaker forms", Marta Di Forti, a researcher at King's College London and study lead author, said in a news release.
According to the researchers "high potency cannabis" especially contain over 10 percent tetrahydrocannabinol or THC.
"If we think there's something particular about (high-potency) cannabis, then making that harder to get a hold of, could be a useful harm-reduction measure", Suzanne Gage of the University of Liverpool, told The Associated Press.
Sugary drinks linked with increased risk of death, study shows
The study found that those who were drinking more sugary beverages had a higher risk of death. Try seltzers or sparking water with a splash of 100% fruit juice .
Microsoft's disc-less Xbox One S gets name and launch date
According to WindowsCentral, it will be a simultaneous release in all markets, and the console will ship without a disc drive. Microsoft has not yet officially confirmed the existence of the new device nor has it spoken about its details, however.
Texas Man Tests Limits of Pet Store’s Leash Policy
An attempt to call management's bluff at the Petco in the Northeast Houston suburb of Atascocita. The staff members were reportedly "super friendly and courteous".
But NORML Deputy Director Paul Armentano said it would be "premature at best, and sensational at worst" to conclude a causal relationship exists between marijuana use and psychiatric disorders.
Di Forti said that high potency cannabis doubled the risks of getting psychosis.
A third of psychosis cases in London are the result of smoking skunk, according to a study that underlines the danger of super-strength cannabis. The link was strongest in London with 30.3 percent of new cases and in Amsterdam with half of the new cases.
Robin Murray, a professor at the IoPPN who also worked on the study, said it should be noted by all policymakers and any potential cannabis users. The estimates on potency also do not include the proportion of cannabidiol (CBD), another important component of cannabis.
Use of high potency cannabis was a strong predictor of psychotic disorder in Amsterdam and London, where high potency cannabis is widely available. The risks are increased when the drug is high in potency, used by children and young people and when taken frequently.
Several past studies have found that more frequent use of pot is associated with a higher risk of psychosis - that is, when someone loses touch with reality. "This proportion is as high as 30 percent in South London and 50 percent in Amsterdam".
The findings were published March 19 in The Lancet Psychiatry journal. They should be aware that using high-potency cannabis comes with a risk, she says.