‘One compound, cannabidiol, or CBD, made people more relaxed. But even small doses of another component, tetrahydrocannabinol, or THC, produced temporary psychotic symptoms in people, including hallucinations and paranoid delusions, doctors said.
The results, to be presented at an international mental health conference in London on Tuesday and Wednesday, provides physical evidence of the drug’s damaging influence on the human brain.
“We’ve long suspected that cannabis is linked to psychoses, but we have never before had scans to show how the mechanism works,” said Dr. Philip McGuire, a professor of psychiatry at King’s College, London.
In analyzing MRI scans of the study’s subjects, McGuire and his colleagues found that THC interfered with activity in the inferior frontal cortex, a region of the brain associated with paranoia.
“THC is switching off that regulator,” McGuire said, effectively unleashing the paranoia usually kept under control by the frontal cortex.’