Experts Issue Statement on Medical Marijuana

Medical marijuana cut some MS symptoms but its effectiveness for other brain diseases was doubtful

/ Author:  / Reviewed by: Joseph V. Madia, MD Beth Bolt, RPh

(RxWiki News) Thus far, 21 states and the District of Columbia have approved medical marijuana use to relieve symptoms of various illnesses. That substance may help some, but not all, people with brain diseases.

In a new analysis of several previous scientific studies, synthetically made medical marijuana in pill and oral spray forms eased some symptoms of multiple sclerosis (MS). But those drugs, manufactured by pharmaceutical companies, did not appear to help with certain symptoms of Parkinson’s disease.

There was not enough evidence to determine whether or not medical marijuana helped reduce certain symptoms of Huntington disease, Tourette’s syndrome, cervical dystonia or epilepsy.

Use of medical marijuana also has such potential side effects as suicidal thoughts and hallucinations, the researchers noted.

"Ask your doctor about brain disease treatment options."

This study’s lead author was Barbara S. Koppel, MD, of New York Medical College in Valhalla, NY.

For this investigation, Dr. Koppel’s research team reviewed 34 studies on medical marijuana use that had been published between 1948 and late 2013. Specifically, these investigators were probing how safely and effectively medical marijuana reduced the following symptoms:

  • Tremors, bladder dysfunction, muscle stiffness, muscle spasms and spasm-related pain of MS, a neurological disorder that leaves patients extremely exhausted and unable to move around normally.
  • Involuntary movements caused by taking the medication levodopa to treat Parkinson’s disease, which causes shaking, difficulty with walking and physical coordination.
  • Involuntary jerking movements of Huntington’s disease, a genetic disorder that also causes dementia.
  • Involuntary neck and shoulder movements of cervical dystonia, a disorder in which painful muscle contractions cause he involuntary movements.
  • Tourette's syndrome tics, which are uncontrolled movements and sounds.
  • The number of seizures brought on by epilepsy, which also can make a patient lose consciousness.

These investigators concluded that medical marijuana pills (Marinol, Cesamet) and oral sprays (Sativex - not approved in the US) can lessen the MS symptoms of muscle spasms; pain, burning and numbness from muscle spasms; and overactive bladder.

Studies were not complete enough to determine if smoking or inhaling marijuana reduced MS symptoms, the researchers wrote.

For Parkinson's disease, these investigators concluded that one synthetic form of medical marijuana, tetrahydrocannabinol pills (Marinol), likely does not help stop involuntary muscle movements resulting from taking levodopa, the main medication prescribed to stem the shaking, stiffness and slow movements that are Parkinson’s symptoms.

There was not enough evidence to explain whether taking synthetic medical marijuana pills, using oral sprays or smoking marijuana safely or effectively reduced:

  • Involuntary jerking symptoms of Huntington's disease
  • Tourette syndrome tics
  • Cervical dystonia
  • Epileptic seizures

Potential side effects of medical marijuana use include nausea, increased weakness, changes in mood or behavior, suicidal thoughts or hallucinations, dizziness or fainting, exhaustion and feelings of being intoxicated. A single seizure was reported in one of the studies, which, in total, involved thousands of patients.

For MS patients who already are deemed at risk for problems with thinking and memory, depression or suicidal thoughts, some of those potential side effects were especially concerning, the researchers wrote. "It's important to note that medical marijuana can worsen” those problems, Dr. Koppel said in an announcement about this research.

According to the studies reviewed, the risk of serious psychological effects was about 1 percent, or about one out of 100 people.

This analysis "highlights the need for more high-quality studies of the long-term efficacy and safety of medical marijuana in the treatment of neurologic diseases,” Dr. Koppel said.

In general, medical marijuana is prescribed as a treatment for use only when standard treatment has not helped.

The American Autonomic Society, the American Epilepsy Society and the International Rett Syndrome Foundation endorsed this analysis, Dr. Koppel and her research team wrote.

These findings were published online April 28 in Neurology. They were scheduled to be presented at the American Academy of Neurology annual conference, April 26 through May 3 in Philadelphia.

The American Academy of Neurology provided funding and other support for this study. The researchers wrote that they did not accept any grants, honoraria or other fees for conducting this review.

Review Date: 
April 24, 2014
Last Updated:
March 12, 2015