People who used high-potency cannabis on a daily basis — with THC levels exceeding 10 percent — were nearly five times more likely to have a psychotic episode, compared with those who didn’t, according to a new study in The Lancet Psychiatry.
In Florida, THC levels can be even higher in products sold for medicinal marijuana.
“The THC levels are as high as 90 percent on concentrated products and 30 percent on flower,” said Victoria Walker, a spokesperson for Trulieve, one of the largest medical marijuana dispensaries in Florida.
Trulieve was the first Florida dispensary to start selling cannabis flower after Gov. Ron DeSantis signed a bill into law on March 18 that revoked a ban on smoking medical marijuana.
In the study, conducted by researchers at King’s College London, researchers collected data on 901 cannabis users, between 2010 and 2015, who were diagnosed with first-episode psychosis after presenting themselves to mental health services during this period. The 901 were culled from 11 study sites across Europe and Brazil.
The 901 were compared with 1,237 individuals in the healthier control group. The study participants were between the ages of 18 and 64.
The researchers concluded people who used low-strength cannabis on a daily basis — with THC levels below 10 percent — were three times more likely to have a psychotic episode, compared with those who had not used cannabis. These rates increased to five times more likely of having a psychotic episode if high-potency cannabis — with TCH levels of 10 percent or more — was consumed daily.
“Our findings confirm previous evidence of the harmful effect on mental health of daily use of cannabis, especially of high-potency types,” the study said.
The report from the United Kingdom comes as more states throughout the United States legalize marijuana for medicinal and recreational purposes. So far, 10 states and the District of Columbia have legalized small amounts of marijuana for adult recreational use, according to NORML, a marijuana advocacy group.
NORML officials said the study is premature and potentially flawed.
“Cannabis use has increased over the years, which puts doubt on the study as incidents of psychosis have generally stayed the same,” said Karen Goldstein, director of NORML Florida.
Added NORML’S national deputy director, Paul Armentano, in a blog post: “It remains premature at best, and sensational at worst to claim that a causal relationship exists between marijuana use and psychiatric disorders on the basis of this new paper.”
He added: “Subjects in the study self-reported their cannabis use. As a result, authors had no ability to verify the THC content of the marijuana consumed by participants.”
Others, however, say the study raises red flags and more research should be done.
“Unfortunately, marijuana has been classified as a Schedule 1 substance by the FDA, and thus hasn’t been studied completely,” Dr. Jennifer Treusch, an Arizona psychiatrist told ABC 15, an Arizona TV station. “We would greatly benefit from having studies done so that we could completely understand what marijuana is doing to the body and mind.”