(CNN) — Multiple sclerosis sufferers may benefit from taking medical marijuana, according to a new study in the journal Neurology.
MS patients who used marijuana either as a pill or as an oral spray found relief from a number of symptoms, according to the study. The findings were released Monday at the annual meeting of the American Academy of Neurology (AAN).
"Medical marijuana can be considered to relieve particular symptoms of MS, including spasticity, pain related to spasms, or central pain from MS lesions," says Dr. Barbara Koppel, main author of the research analysis.
Koppel, a neurologist at New York Medical College in New York, says medical marijuana did not help MS patients who had tremors, nor did it relieve abnormal involuntary movements in late-stage Parkinson's disease. Researchers also didn't find enough evidence to recommend the treatment for other conditions they looked at, including epilepsy, she says.
Researchers looked at whether use of medical marijuana was safe and effective for other neurological diseases like motor symptoms in Huntington's disease, tics in Tourette's syndrome and cervical dystonia or abnormal neck movements. They decided there was not enough information to make a determination.
"Expected side effects such as fatigue, dizziness and nausea were found in the studies but rarely led to (people) dropping out of the study," says Koppel.
MS is an autoimmune disease affecting the brain and spinal cord. It's caused when the protective covering around the nerve cells is damaged by inflammation. There is no single test for MS, nor is there a cure. There are several medications that can help slow down and control symptoms. The disease is usually diagnosed between the ages of 20 and 40 and more women are diagnosed than men.
Researchers looked at 34 different studies involving approximately 2,000 patients -- the bulk of them in England and Germany. European regulators approved the cannabis spray Sativex for the treatment of MS spasticity in 2010, and it's now available in 25 countries worldwide. The drug is not available in the United States.
Less than 1% of trial participants taking cannabis pills or spray had serious side effects like hallucinations and seizures. In two of the studies analyzed, patients actually smoked marijuana, but there was not enough information available to determine if that was effective.
According to Koppel, medical marijuana can worsen cognitive function and memory. Her concern is that MS patients may already experience some of these issues as a result of the disease.
People with some of these diseases "already have higher rates of depression and suicidal ideation than the general public," Koppel says. "If you have a brain disease like MS, for example, you may already have some depression or cognitive impairment, so we were careful to see if cannabis made this worse."
While the studies did not find a direct link to depression, Koppel says it still suggests this is something patients and physicians should be aware of.
Dr. Timothy Coetzee, chief advocacy, services and research officer at the National MS Society, says his organization supports the rights of MS patients to work with their doctors to get access to medical marijuana in states where medical use has been legalized.
“The society supports the need for more research to better understand the benefits and potential risks of marijuana and its derivatives as a treatment for MS," Coetzee says. "We intend to work towards removing barriers impeding such research into the use of marijuana for medical purposes. As with any MS therapy, along with its potential benefits come potential side effects that also need to be evaluated.”
Koppel says more research is needed with more formulations of cannabis, not only in the diseases already looked at, but also in other neurologic conditions.