By Traci PedersenAssociate News Editor
A certain marijuana compound known as cannabidiol (CBD) can treat schizophrenia as well as antipsychotic drugs, with far fewer side effects, according to a preliminary clinical trial.
The research team, led by Markus Leweke of the University of Cologne in Germany, studied 39 people with schizophrenia who were hospitalized for a psychotic episode. Nineteen patients were treated with amisulpride, an antipsychotic medication that is not approved in the U.S., but is similar to other approved drugs. The remaining 20 patients were given CBD, a substance found in marijuana that is considered responsible for the mellowing or anxiety-reducing effects. Unlike the main ingredient in marijuana, THC, which can trigger psychotic episodes and worsen schizophrenia, CBD has antipsychotic effects, according to prior research in both animals and humans.
Neither the patients nor the scientists knew who was receiving which drug. At the end of the four-week trial, both groups made significant clinical improvements in their schizophrenic symptoms, and there was no difference between those getting CBD or amisulpride. “The results were amazing,” said Daniel Piomelli, Ph.D., professor of pharmacology at the University of California-Irvine and a co-author of the study. “Not only was [CBD] as effective as standard antipsychotics, but it was also essentially free of the typical side effects seen with antipsychotic drugs.”
Antipsychotic drugs may cause devastating and sometimes permanent movement disorders; they can also lower a patient’s motivation and pleasure. The new generation of these drugs can also lead to weight gain and increase the risk for diabetes. These side effects are well known as a major hindrance during treatment. In the German study, weight gain and movement problems were observed in patients taking amisulpride, but not CBD.
“These exciting findings should stimulate a great deal of research,” said Dr. John Krystal, chair of psychiatry at Yale University School of Medicine, who was not associated with the research. He notes that CBD not only had fewer side effects, but also seemed to work better on schizophrenia’s so-called “negative symptoms,” which are notoriously hard to treat. Negative symptoms of schizophrenia include social withdrawal, a lowered sense of pleasure and a lack of motivation. However, since current antipsychotic medications can actually cause these negative symptoms, it wasn’t clear whether CBD was better than amisulpride at getting rid of these symptoms, or whether CBD simply caused fewer side effects to begin with.
If replicated, the results suggest that CBD may be at least as effective as current medications for the treatment of schizophrenia, without the severe side effects that make patients reluctant to take medication.
“The real problem with CBD is that it’s hard to develop for a variety of silly reasons,” said Piomelli. Since it comes from marijuana, there are obvious political issues surrounding its use. Extracting it from the plant is also expensive.
But the biggest obstacle may be that CBD is a natural compound, and therefore can’t be patented the way new drugs are. So although CBD could outsell the current blockbuster antipsychotic drugs, pharmaceutical companies aren’t likely to develop it. Researchers are working to develop synthetic versions of CBD that would avoid such hurdles. “We have one and are hoping to move forward in the near future,” Piomelli said.
The study is published online in the journal Translational Psychiatry.