Medical marijuana appears to help combat some multiple sclerosis symptoms but has no effect on problems associated with Parkinson's disease and several other brain disorders, scientists reported Monday.
In an effort to discover how marijuana affects these disorders, researchers with the American Academy of Neurology reviewed 34 studies published between 1948 through 2013. The aim was to find when the drug is safe and efficacious -- and when it isn't.
The academy's research comes on the heels of a heart study last week reported by French researchers who did not condemn pot, but called for additional scientific research on its possible cardiac complications.
Dr. Barbara Koppel of New York Medical College in Valhalla, a neurology academy fellow, led the new analysis and presented her findings Monday in the journal Neurology.
Working with researchers from numerous institutions, including Columbia University, the University of California, Los Angeles, and the University of Arizona, Koppel concluded that certain forms of marijuana -- pill or oral spray -- can help abate the spasticity of multiple sclerosis.
But she underscored that marijuana, which contains at least 60 known pharmacological compounds -- so-called cannabinoids -- should not be viewed as a panacea.
"It's important to note that medical marijuana can worsen thinking and memory problems since many people with MS suffer from these problems already, due to the disease itself," Koppel said.
Not effective against Parkinson's
The study found that marijuana does not effectively treat Parkinson's patients who develop movement disturbances in the disorder's later stages as a result of the typically prescribed drug levodopa.
Koppel's review also found that marijuana does not alleviate tics caused by Tourette syndrome, movement problems in Huntington's disease or seizures caused by epilepsy.
Dr. Karen Blitz, director of the MS program at North Shore-LIJ Multiple Sclerosis Center in East Meadow, said recommending medications to people with multiple sclerosis has to be undertaken with great care.
"The study shows that marijuana definitely had a positive effect reducing spasticity in patients," Blitz said Monday. "The problem is that 50 percent of MS patients have cognitive impairment so it wouldn't be wise to give them a treatment that affects thinking and cognition."
Blitz added that there are already several scientifically vetted and approved medications available to treat multiple sclerosis-related spasticity.
Marjiuana still not legal in NY
There are other reasons Blitz said she wouldn't recommend the controversial drug to patients: "It's not legal in New York and it's not approved," she said.
But Mitch Earleywine, an Albany psychologist and executive director of NORML -- National Organization for the Reform of Marijuana Laws -- said he's pleased with the analysis' findings and hopes for additional studies on other conditions.
"The bottom-line is that the evidence for MS looks very compelling," he said.
Earleywine said he hopes additional research proves the plant works well for epilepsy.
But Dr. Alan Ettinger, epilepsy director at Neurological Surgery, P.C., in Rockville Centre, isn't certain that will be anytime soon.
He, too, cited other medical measures to address seizures and said he does not trust emerging anecdotal evidence on the benefits of marijuana for seizures. Ettinger has authored textbooks on epilepsy and said he would only recommend marijuana to his patients when the disease is catastrophic and all conventional treatments have been exhausted.
Although he applauded the neurology academy's new study, Ettinger said future research needs to be more extensive.
Koppel's study, he said, is based on a tried-and-true scientific method in which evidence is gathered from numerous studies and then reanalyzed."Their study is what is called a meta analysis and while a meta analysis sounds like a very scientifically rigorous way of looking at evidence, the quality of a meta analysis is only as good as the data they were able to examine," Ettinger said.
Ettinger emphasized that epilepsy is not a single disorder and is too complex to be treated by a single drug .