Oral and spray forms of medical marijuana can help treat some symptoms of multiple sclerosis (MS), according to a systematic review conducted by the American Academy of Neurology (AAN) on the use of medical marijuana in brain diseases.
“Primary care physicians should inform their MS patients that medical marijuana may be helpful and use the side effects information in the review to caution patients about what they might expect,” review author Barbara S. Koppel, MD, Chief of Neurology and Professor of Clinical Neurology at New York Medical College in New York, told ConsultantLive.
Dr Koppel announced the results of the review of 34 studies at a press conference at the AAN’s annual meeting in Philadelphia.
In the review, not enough evidence was found to show whether medical marijuana is helpful in treating patients with Parkinson disease, motor problems in Huntington disease, tics in Tourette syndrome, or cervical dystonia and seizures in epilepsy, Dr Koppel noted.
“The AAN review also highlights the need for more high-quality studies of the long-term efficacy and safety of medical marijuana in the treatment of neurologic diseases,” she said.
The review found that medical marijuana only in pill or oral spray form can help treat some symptoms of MS. These include spasticity, certain types of pain (pain related to spasticity, including painful spasms, and painful burning and numbness), and overactive bladder.
Most of the MS studies examined pill or oral spray forms of medical marijuana. Two studies examined smoked medical marijuana for treating MS symptoms; however, the studies did not provide enough information to show whether smoked medical marijuana is effective.
“Physicians who live in a state that has legalized medical marijuana may prescribe it for the symptoms that it helps,” said Dr Koppel.
Overall, adverse effects reported in at least 2 studies in the review included nausea, increased weakness, behavioral or mood changes, suicidal thoughts or hallucinations, dizziness or fainting symptoms, fatigue, and feelings of intoxication. “It’s important to note that medical marijuana can worsen thinking and memory problems, and this is a concern since many people with MS and Parkinson’s disease suffer from these problems already due to the disease itself,” said Dr Koppel.
For Parkinson disease, the review concluded that medical marijuana in the form of synthetic tetrahydrocannabinol (THC) pills likely does not help relieve abnormal movements induced by levodopa, which can develop in the late stages of the disease.
Dr Koppel noted that 2 seizures related to cannabinoid pills were reported in 1 large MS study.
For epilepsy, Dr Koppel suggested clinicians “encourage a patient to enroll in a study rather than go to the corner and smoke some,” noting that these studies rigorously define the amounts of ingredients in the medical marijuana products, which are not defined in marijuana that is smoked.
“The amount of THC in pill or spray form largely determined the amount of intoxication patients felt,” Dr Koppel said. Researchers are leaning toward formulas that include more cannabinoids, which seem to lead to fewer adverse effects.
The review also will be published in the April 29, 2014, issue of Neurology.