A study reported by neuroscientists finds that a non-psychoactive compound in cannabis called cannabidiol, or CBD, appears to protect against the long-term negative psychiatric effects of THC, the primary psychoactive ingredient. To conduct their study, three groups received 3 mg/kg of either THC, CBD, or THC+CBD every day for three weeks. The other two groups received a placebo or no treatment. All mice were then tested for signs of impaired memory, obsessive-compulsive behaviors and anxiety immediately and six weeks later.
The mice exposed to THC alone showed signs of impaired memory and increased obsessive-compulsive behavior immediately after treatment. The adolescent group still experienced these changes six weeks after treatment, whereas the adult group did not. Both groups experienced a long-term increase in anxiety. By contrast, adult and adolescent mice that received CBD alone or CBD+THC exhibited no short- or long-term behavioral changes. These results suggest that long-term use of cannabis strains containing similar amounts of CBD and THC may be less harmful than long-term use of high-THC strains. An analysis of cannabis seized by the U.S. Drug Enforcement Administration found that while THC levels rose 300 percent from 1995 to 2014, the levels of CBD have declined 60 percent.