Helpful or Harmful?
Medicinal Value of Marijuana Remains Unclear

June 7, 2004, St. Paul MN. - Despite limited evidence of effectiveness, many epilepsy and multiple sclerosis patients believe marijuana is an effective treatment and are actively using it, according to two Canadian studies published in the June 8 issue of Neurology , the scientific journal of the American Academy of Neurology.

Multiple sclerosis patients in Halifax, Nova Scotia, and epilepsy patients in Edmonton, Alberta, recently participated in a questionnaire and a telephone survey, respectively, regarding patterns, prevalence and perceived effects of marijuana use. Results of these surveys may raise more questions than they answer.

In the study of epilepsy patients from the University of Alberta Epilepsy Clinic, 136 subjects responded to the phone survey. Of these, nearly half had used marijuana in their lifetime; one in five had used marijuana in the past year; 20 (15 percent) had used in the past month; 18 (13 percent) used more than 48 days per year; and 11 (8 percent) used more than half the days of the year. Four patients were actually considered marijuana dependent. Odds of frequent marijuana use were eight times greater for patients with frequent seizures and 10 times greater for those who had had epilepsy for at least five years.

One possible explanation for the association of marijuana use with seizure frequency is that patients who experience more frequent seizures might be more likely to try alternative treatments.

"Studies suggest one-third of the general population use alternative health care on a yearly basis,"notes study author Donald Gross, MD, FRCP, of the University of Alberta, Edmonton. "Not surprisingly, patients tend to look to alternative therapies in situations where conventional medicine has been unsuccessful, in particular, for chronic medical conditions. The finding of increased marijuana use in epilepsy patients with longer duration of disease and frequent seizures is consistent with the findings regarding other forms of non-conventional therapies."

Another possible explanation for the correlation between increased seizure frequency and more frequent marijuana use is that there is a causal relationship between marijuana use and seizures, i.e. marijuana use leads to increased seizure frequency.

In the study of multiple sclerosis patients from Halifax, 205 subjects completed a survey questionnaire. Of the 34 identified medical marijuana users, more than half perceived it as being a very effective treatment, and more than half also reported using it within the previous 24 hours. Nineteen patients reportedly used marijuana more than one time per week, with eight patients reporting more than one daily use.

"We have learned several things from these patients," concludes study author Mark Ware, MBBS, MRCP, of McGill University, Montreal, who co-authored the study with John Clark, MD, FRCPC, of Capital Health and the Dalhousie University Faculty of Medicine, Halifax. "Firstly, that pain and spasms are not the only reasons for use, and the effects of marijuana on mood, sleep and stress are important areas of therapeutic need and should be addressed in clinical trials. Secondly, there is a wide variance in doses used, ranging from single puffs to more than a gram at a time. Clinical trials will also need to include early dose-finding phases and allow for subject variability in dose adjustments. Thirdly, marijuana appears to be well-tolerated, though some subjects experienced intolerable side effects and deterioration of symptoms."

Access to marijuana also emerged as an important obstacle in the use of this drug for medical purposes.

Nearly one in four epilepsy patients and one in six multiple sclerosis patients believe that marijuana is an effective form of treatment for their disease symptoms, and many are currently using marijuana therapeutically. Carefully controlled clinical trials are recommended by both study teams to determine the efficacy of marijuana in the treatment of epilepsy and multiple sclerosis.

The study by Gross et al received support from the University of Alberta Hospital Foundation. The study by Ware et al received support from a Dalhousie University summer research student award, Canadian Institutes of Health Research and the Fonds de la Recherche en Santé du Quebec.

The American Academy of Neurology, an association of more than 18,000 neurologists and neuroscience professionals, is dedicated to improving patient care through education and research. A neurologist is a doctor with specialized training in diagnosing, treating and managing disorders of the brain and nervous system such as stroke, Alzheimer's disease, epilepsy, Parkinson's disease, and multiple sclerosis.

For more information about the American Academy of Neurology, visit its website at www.aan.com.

Editor's Note: An editorial commenting on these studies is also published in the June 8 issue of
Neurology .

Media Contacts:

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Kathy Stone
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American Academy of Neurology
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Marilee Reu
Media Relations Administrator
American Academy of Neurology
651-695-2789
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