July 28 (UPI) -- People with cannabis use disorders can safely use cannabidiol, or CBD, to reduce their reliance on the drug, a study published Tuesday by The Lancet Psychiatry found.
Although the Phase 2 study was designed to assess safety -- and not effectiveness -- of CBD for cannabis use disorder, preliminary findings indicate that a daily dose of 400 or 800 milligrams helps people with the condition abstain from using the drug, researchers said.
However, they cautioned against "self-medication" with commercially available products because they do not contain enough CBD -- usually about 25 mg. -- and have not been tested for quality and safety.
"Our study provides the first causal evidence to support CBD as a treatment for cannabis use disorders," study co-author Dr. Tom Freeman said in a statement.
"This is encouraging" because although cannabis addiction affects an estimated 22 million people worldwide, "there are currently no drug treatments for cannabis addiction," said Freeman, director of the Addiction and Mental Health Group at the University of Bath in England.
Cannabis use disorders include abuse of or dependence on marijuana that cause problems in life or carry a compulsive need to use the drug, according to previous research.
CBD is one of more than 80 chemicals present in cannabis, or marijuana. By itself, CBD has been reported to induce feelings of relaxation and calm, but not the "high" associated with cannabis use -- which is caused by the chemical tetrahydrocannabinol, or THC -- the researchers said.
Earlier studies have suggested that taking CBD might help to reduce withdrawal symptoms in people trying to stop using cannabis. However, they either used an open-label design -- in which participants knew what medications they were taking, biasing the results -- or CBD was given together with THC, the researchers said.
For their study, Freeman and his colleagues enrolled 82 people diagnosed with a cannabis use disorder of at least moderate severity, which means they experienced at least four out of 11 possible symptoms of addiction.
All of the study participants had expressed a desire to quit cannabis use within the next month, and had tried to quit at least once before, the researchers said.
Participants were were asked to take either two capsules of CBD, or placebo capsules containing no CBD, twice daily for four weeks, they said.
The CBD capsules contained either 200 mg., 400 mg. or 800 mg. of CBD, with 12 participants receiving each dose amount, the researchers said.
In addition, all participants underwent six counseling sessions designed to help them quit using cannabis, which took place before and during the study period, according to the researchers.
Participants underwent weekly urine testing to measure levels of THC, and they were also asked to report how many days they had abstained from using cannabis during the past week, the researchers said.
After the first phase of the study, the 200 mg. dose was found to be ineffective and these participants were removed from the trial, they said. An additional 34 people were recruited to the second stage of the study and randomly assigned to receive daily doses of either the placebo, 400 mg. CBD or 800 mg. CBD, according to the researchers.
Daily CBD doses of 400 mg. and 800 mg. were both found to reduce participants' cannabis intake, based on levels of THC in the participants' urine, with the higher dose appearing to be more effective, the researchers said.
In addition, abstinence from cannabis use increased by an average of 0.5 days per week in the group who received the 400 mg. daily dose of CBD and 0.3 days per week in the group who received 800 mg. CBD daily, they said.
There were no serious side effects during the study, suggesting that CBD is safe and well tolerated at the doses tested, according to the researchers.
These findings are important in light of recent increases in the number of people entering treatment for cannabis use disorders worldwide, they said.
"People with concerns about their cannabis use should always speak to a healthcare professional," Freeman said.