Mixed results for MS cannabis study
The first major trial exploring anecdotal claims that cannabis benefits people with multiple sclerosis has yielded mixed results, with a disparity between objective clinical measurements of symptoms and patients’ own reports of improvement.
Of the patients given cannabinoids (cannabis derivatives), 60 per cent reported a reduction of muscle stiffness and jerking movements, compared to only 45 per cent of those on the placebo. But when spasticity – as these symptoms are termed – was measured objectively on a widely used scale, no improvement was detected.
There were improvements in pain for 54 per cent of patients on cannabinoids, compared to 37 per cent in the placebo group, but again the reliability of this subjective measure is in question. Study author John Zajicek from the University of Plymouth and his colleagues hypothesise that patients may have become aware of the treatment they were receiving because of the side effects.
There were 630 MS patients taking part in the trial, which was funded by the Medical Research Council. Around a third received oral cannabis extract; one third were given D9-tetrahydrocannabinol or THC (the active ingredient in cannabis); and the remainder formed the placebo group.
A quantitative measure of patients’ mobility yielded more positive results, with all three groups taking less time to walk a short distance. There was a 12 per cent reduction in the THC patients, compared to 4 per cent in the other two groups.
Dr Zajicek points out that spasticity is a very difficult phenomenon to measure as it comprises signs obvious to external assessors as well as symptoms reported by patients.
“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.”
Chief executive of the Multiple Sclerosis Society, Mike O’Donovan, agrees the results demonstrate the problems of assessing treatments for a variable and fluctuating conditions like MS, with current methods often overlooking benefits observed by patients.
But he points out: “Around two-thirds of those on the cannabis-derived drugs felt their spasticity was improved by them, even though that could not be shown clinically. More people on the drugs found relief from other very distressing symptoms like pain, spasm and sleeping problems than those taking a placebo.”
Because these improvements can make a tremendous difference to people with MS, who have limited treatment options, the MS Society argues those who might benefit should have the treatment prescribed on the NHS.
The paper is published today in The Lancet.
