Public Release: 

Mixed results for study investigating potential of cannabis treatment for MS

Lancet

Results of the first large-scale randomised trial to assess the potential benefit of cannabis in the treatment of multiple sclerosis are detailed in this week's issue of THE LANCET. Although the main research finding shows no improvement in spasticity scores among patients given cannabinoids compared with placebo, the results suggest that cannabinoids could have potential clinical use for improving patients' mobility and pain control.

Multiple sclerosis (MS) is associated with muscle stiffness, spasms, pain, and tremor. Much anecdotal evidence suggests that cannabinoids (cannabis derivatives) could help these symptoms. John Zajicek from the University of Plymouth, UK, and colleagues report the findings from the first large-scale randomised trial (funded by the UK Medical Research Council) to investigate the effect of oral cannabinoids on spasticity and other symptoms related to multiple sclerosis.

630 MS patients receiving treatment from 33 UK centres were randomised into three groups (two treatment groups, one placebo group): oral cannabis extract (211 patients), D9-tetrahydrocannabinol (THC, 206 patients), or placebo (213 patients). Assessment took place after 15 weeks, with changes in spasticity (muscle stiffness and jerking movements) objectively assessed using the Ashworth scale being the primary outcome measure of the study.

There was no evidence of a difference in spasticity scores between patients given cannabinoids compared with those given placebo. In all three groups, whilst on treatment, patients were observed to have a small reduction in time taken to walk a short distance-by 12% in the patients who received THC compared with 4% in both the cannabis extract and placebo groups. 60% of patients in the cannabinoid treatment groups reported subjective improvements in spasticity compared with 46% in the placebo group, and 54% of patients given cannabinoids reported improvements in pain compared with 37% in the placebo group. However, 'unmasking' - when patients become aware, owing to side effects, of the treatment they are receiving- may explain some of these subjective ratings.

John Zajicek comments: "Spasticity is a highly complex phenomenon, composed of both signs observable to assessors and symptoms reported by patients. Our results, using the Ashworth score as the primary outcome measure, exclude any major effect of treatment of spasticity with cannabinoids, but the effect of spasticity and pain as assessed by patients indicates a symptomatic subjective clinical effect. There was also a beneficial effect on walking time. Our findings therefore provide some evidence that cannabinoids could be clinically useful in treatment of symptoms related to multiple sclerosis, but more work is necessary, using outcome measures that more adequately assess the effect of symptoms in chronic disease."

In an accompanying Commentary (p 1513), Luanne Metz and Stacey Page from the University of Calgary, Canada, conclude: "We now have as much evidence to support the use of these oral cannabinoids for spasticity in ambulatory people with multiple sclerosis as we do for many standard therapies for spasticity, including baclofen. However, because we do not know how these cannabinoids compare to other anti-spasticity treatments, they should generally only be considered when other therapy has failed...

Finally, we still have no data to compare the risks and benefits of smoked cannabis. Hopefully, this study will stimulate further research to develop and evaluate safe, effective formulations of cannabis, and will inform debate over the social and legal restrictions that limit its use. In the meantime, when other treatment inadequately controls spasticity, oral cannabinoids should be considered where law permits their possession and use."

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Contact: Medical Research Council Press Office, Park Crescent, London W1, UK; T): 44-0-20-7637-6011; E): press.office@headoffice.mrc.ac.uk. Professor Luanne M Metz, Foothills Hospital, 1403-29 St NW, Calgary, Alberta, Canada T2N 2T9; E): lmetz@ucalgary.ca.

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