Philadelphia, PA—A systematic literature review conducted by the American Academy of Neurology (AAN) shows that certain forms of medical marijuana can be useful to treat some symptoms of multiple sclerosis (MS), but the evidence is insufficient to support its use in other neurologic diseases, and there are a number of safety concerns with medical marijuana.
Barbara Koppel, MD, Chief of Neurology, Metropolitan Hospital in New York City, reported the results of the analysis at the 2014 meeting of the AAN, which was recently published in Neurology (2014;82:1556-1563).
Because studies used various doses and different preparations of marijuana, the analysis was conducted by the type of cannabinoid.
“The review finds that certain forms of medical marijuana can be helpful to treat some symptoms of MS, but it did not appear to be helpful in treating drug-induced movements of Parkinson disease,” Dr Koppel said. “There was not enough evidence found to show if medical marijuana is helpful in treating motor problems in Huntington disease, tics in Tourette syndrome, and in reducing the number of seizures in epilepsy.”
The evidence indicates that pills and oral spray forms of marijuana can help treat some symptoms of MS, including spasticity; certain types of pain, including painful spasms, pain related to spasticity, and central pain; and symptoms of overactive bladder.
Most of the studies on MS examined pill or oral spray forms of marijuana, but 2 studies examined smoked medical marijuana for the treatment of the same symptoms. “However, these studies did not provide enough information to show if smoking marijuana is effective,” she said.
For patients with Parkinson disease (PD), medical marijuana in the form of synthetic ∆9-tetrahydrocannabinol pills does not help reduce the number of involuntary abnormal movements induced by levodopa that can develop in the late stages of the disease.
There was not enough information to show if medical marijuana, including smoked marijuana, is safe and effective in the following neurologic diseases: the motor symptoms of Huntington disease, tics in Tourette syndrome, cervical dystonia, and seizures in epilepsy.
“In general, medical marijuana is prescribed as a treatment for use only when standard treatment was not helpful in controlling all of the patient’s symptoms, and the standard treatment was allowed to be continued during most of these studies,” said Dr Koppel.
The side effects with medical marijuana that were reported in more than 2 studies included nausea, fatigue, increased weakness, behavioral or mood changes, suicidal thoughts or hallucinations, dizziness, fainting symptoms, and feelings of intoxication (feeling “high”), as well as reports of 2 seizures.
“Mood changes and suicidal thoughts are of special concern when a medication is used in patients with a neurologic illness, such as MS or PD, because they are at increased risk of depression and suicide,” Dr Koppel said. “The studies showed the risk of serious psychological effects overall to be 1%.”
Although seldom prescribed, she noted that patients may still be using it on their own, and patients who obtain cannabis from dispensaries in states where medical use is legal fail to get specific advice on its use from their physicians.
She concluded, “There is a place for it, and more work is going to need to be done to figure out exactly where its indications will be.”
Added Gary Gronseth, MD, Vice Chairman of Neurology, University of Kansas Medical Center, Kansas City, “When we say something like, there’s insufficient information or insufficient evidence to indicate that it’s effective for a condition, that’s not the same thing as saying that there’s evidence that it’s not effective for that condition, and that’s a common way that we confuse these statements.”