The question of whether marijuana — produced from the flowering top of the hemp plant, Cannabis sativa — should be used for symptom management in multiple sclerosis (MS) is a complex one. It is generally agreed that better therapies are needed for distressing symptoms of MS — including pain, tremor and spasticity — that may not be sufficiently relieved by available treatments. Development of more treatments for MS symptoms is a priority for the National Society in its 2011-2015 strategic response. Still, there are uncertainties about the benefits of marijuana relative to its side effects. The fact that marijuana is an illegal drug in many states and by federal statute (see Supreme Court ruling below) further complicates the issue.
Some people with MS report that smoking marijuana relieves several of their MS symptoms. However, for any therapy to be recognized as an effective treatment, anecdotal reporting must be supported by carefully gathered objective evidence of safety and benefit. Unfortunately, it has proven difficult to do carefully controlled clinical trials of marijuana. One reason for this is that marijuana is psychoactive and makes people feel "high." This means that people taking the active drug during a clinical trial usually become aware of it — thus "unblinding" the study and possibly biasing results. Studies completed thus far have not provided convincing evidence that marijuana or its derivatives provide substantiated benefits for symptoms of MS.
Conflicting results of previous research, coupled with the need for additional therapies to treat symptoms of MS, make it important that more research be done on the potential of marijuana and its derivatives. The Society established a task force to examine the use of cannabis in MS and review what is currently known about its potential. This task force made specific recommendations on the research that still needs to be done to answer pressing questions about the potential effectiveness and safety of marijuana and its derivatives in treating MS. The Society is currently funding a controlled study on the effectiveness of different forms of marijuana to treat spasticity in MS.
Early studies examining marijuana & MS
Early studies explored the role of THC (tetrahydrocannabinol — an active ingredient in marijuana) or smoked marijuana in treating spasticity, tremor and balance control in small numbers of people with MS. Most of these studies were done with THC. Because THC can be given by mouth, it is easier to control the dose. The results of these studies were mixed, and participants reported a variety of uncomfortable side effects. In addition, smoked marijuana poses health risks that are at least as significant as those associated with tobacco.
For spasticity (unusual muscle tension or stiffness) — Studies of THC for spasticity have had mixed results. While some people reported feeling "looseness" and less spasticity, this could not always be confirmed by objective testing done by physicians. Even at its best, effects lasted less than three hours. Side effects, especially at higher doses, included weakness, dry mouth, dizziness, mental clouding, short-term memory impairment, space-time distortions and lack of coordination.
For tremor (uncontrolled movements) — In a small study of THC involving eight seriously disabled individuals with significant tremor and ataxia (lack of muscle coordination), two people reported improvement in tremor that could be confirmed by an examination by a physician and another three reported improvement in tremor that could not be confirmed. All eight patients taking THC experienced a "high," and two reported feelings of discomfort and unease.
For balance — Smoked marijuana was shown to worsen control of posture and balance in 10 people with MS and 10 who did not have MS. All 20 study participants reported feeling "high."
Study on marijuana derivatives in mice
Investigators in the United Kingdom and United States tested the ability of two marijuana derivatives and three synthetic cannabinoids to control spasticity and tremor, symptoms of the MS-like disease, EAE, in mice. The results, published in the March 2, 2000 issue of Nature, suggested that four different cannabinoids could temporarily relieve spasticity and/or tremor. While the study suggested that similar derivatives of marijuana might be developed for human use, it was clear that the psychoactive effects of these cannabinoids would need to be reduced sufficiently to make them a safe and comfortable treatment for people with MS.
On June 6, 2005, the Supreme Court ruled that the federal government has the power to prohibit and prosecute the possession and use of marijuana for medical purposes — even in the 20 states (Alaska, Arizona, California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Maine, Massachusetts, Michigan, Montana, Nevada, New Hampshire, New Jersey, New Mexico, Oregon, Rhode Island, Vermont and Washington) and Washington, D.C., where it is currently legal.
The decision overturned a 2003 ruling by a federal appeals court that shielded California's Compassionate Use Act, the medical-marijuana initiative adopted by the state's voters nine years ago, from federal drug enforcement. The appeals court had held that Congress lacked constitutional authority to regulate the noncommercial cultivation and use of marijuana that did not cross state lines.
The current decision reinforces the government's authority over intra-state activities that might impact interstate commerce.