A new study raises concerns for those who indulge in potent forms of marijuana. Researchers out of King’s College London and Rome's Sapienza University studied brain scans of 56 patients who had reported an episode of psychosis and 43 healthy volunteers. They found that those who regularly smoked high-strength cannabis showed small changes in the region of the brain that sends messages between the left and right sides, reports the Guardian. The alteration in this region, called the corpus callosum, "reflects a problem in the white matter that ultimately makes it less efficient," says neurobiologist Paola Dazzan. The brains of people who had never used cannabis or smoked less potent forms looked normal, leading researchers to conclude that high-strength versions, like skunk, may damage nerve fibers.
The UK Times reports the damage is similar to the effects of a concussion. "We don't know exactly what it means for the person, but it suggests there is less efficient transfer of information," Dazzan says, per Yahoo. So what's doing the damage? Dazzan believes it's the THC in cannabis; less potent varieties contain 2% to 4% THC, while more potent forms contain 10% to 14%. The chemical acts on the cannabinoid receptors found in the corpus callosum, according to a release. Though researchers haven't proven cannabis is responsible for the changes, "it is extremely important to gather information on how often and what type of cannabis is being used," Dazzan says. "These details can help quantify the risk of mental health problems and increase awareness of the type of damage these substances can do." (Potent pot also raises your psychosis risk.)