Multiple sclerosis (MS) is a complex disease that is thought to arise when the immune system malfunctions and attacks the nervous system. Estimates suggest that around 200 people are in the U.S. are diagnosed with the condition each week, with women affected twice as often as men.
People with MS experience symptoms that can range in severity and duration. One of the most common symptoms of MS is spasticity, which causes painful, uncontrollable muscle spasms. Spasticity can affect any part of the body, but it occurs most often in the legs. Other symptoms of MS include clumsiness, vision problems, tingling or numbness in the limbs, weak muscles and bladder control problems. Often, people with MS have periods when they experience symptoms, called attacks, followed by periods without symptoms, called remission.
There is no known cure for MS, but a combination of treatments can help manage the disease. Treatment of MS has two aspects: immunomodulatory therapy (IMT), which reduces the frequency of attacks and slows the progression of the disease, and therapies to relieve symptoms. Conventional treatments for MS often put patients at risk for a variety of side effects, including drowsiness, dizziness, weakness, nausea and diarrhea. Thus, the need for new treatments that relieve the symptoms of the disease with fewer side effects is clear.
Numerous studies have revealed the benefits of medicinal cannabis, or marijuana, for alleviating multiple MS symptoms. In 2003, Zajicek et al. conducted one of the largest studies investigating the effect of medicinal cannabis on patients with the disease. The results revealed self-reported improvements in pain, spasms, spasticity and sleep quality in participants who used whole-plant cannabis-based medicine (CBM) extracts or tetrahydrocannabinol (THC). A study by Collin et al. in 2007 supported the findings of Zajicek et al. In a trial of CBM for the treatment of spasticity caused by MS, researchers found that participants who used CBM recorded significantly improved scores on the Numerical Rating Scale, an 11-point scale for self-reporting of spasticity. Additionally, research by Corey-Bloom of the University of California, San Diego revealed a significant reduction in spasticity in participants who were already on medication for MS and who smoked cannabis once daily for three days during the trial.
Multiple studies have also shown the efficacy of medicinal cannabis in treating neuropathic pain, the most common type of pain experienced by people with MS. A study conducted by researchers at the University of California, Davis between 2009 and 2011 revealed that vaporized cannabis significantly reduced neuropathic pain in people with MS, without affecting mood. The majority of the participants in the study were experiencing neuropathic pain despite traditional therapy. Research by Wade et al. in 2013 produced similar findings to those of the University of California study. In a study of 24 patients with neurogenic symptoms unresponsive to standard treatments, Wade et al. found that whole-plant cannabis extracts provided significantly superior pain relief compared with placebo. Additionally, the results of research by Wilsey et al. in 2008 and Ware et al. in 2010 contribute to mounting evidence that cannabis may be effective at relieving neuropathic pain and may be an alternative for people who do not respond to, or cannot tolerate, conventional therapies.
A review by Pertwee et al. in 2007 found evidence to suggest that medicinal cannabis may be useful beyond symptom control in people with MS. The chemicals, or cannabinoids, in medicinal cannabis are structurally similar to endogenous cannabinoids, which are naturally occurring chemicals that help to regulate nerve impulse transmission. Because of this similarity, it is hypothesized that they can attach themselves to molecules called CB2 cannabinoid receptors on immune cells within the nervous system and activate them, decreasing inflammation and suppressing some of the changes that give rise to the progression of MS. Research by Ben-Shabat et al. in 1998 revealed that cannabinoids may work more effectively in combination than alone: an observation termed the entourage effect. Thus, whole-plant CBM may relieve the symptoms of MS better than a medicine containing only one or two cannabinoids.
Given its high efficacy and low risk of adverse effects, whole-plant CBM may be an effective add-on treatment for people with MS; however, federal law still classifies cannabis as a Schedule I drug with no medicinal benefit. As a result, many people with MS are being denied access to a potentially life-changing therapy. Proponents of medicinal cannabis are campaigning for a change to federal law so that the thousands of Americans who live with MS can have safe, legal access to medical marijuana under a physician's guidance. Many high-profile national and international health organizations, including the Montel Williams MS Foundation and the American Academy of Family Physicians, support the outright legalization of medicinal cannabis. Legalization would enable people with MS to use cannabis to manage their symptoms more effectively and perhaps even delay progression of the disease, without fearing the potential legal repercussions.