Cannabis 'does not slow progress of multiple sclerosis', scientists claim in blow to hopes drug could provide relief to sufferers
Researchers found patients who took capsules containing THC, a key active ingredient in cannabis, fared no better than those given a placeboStudy assessed MS patients on both a disability scale administered by neurologists and another based on their own reporting
15:55 GMT, 29 May 2012
Cannabis does not slow the progression of multiple sclerosis, a large-scale study has concluded.
The three-year study at the Peninsula College of Medicine and Dentistry at Plymouth University is a blow to hopes that the drug could provide long-term benefits for patients with the debilitating nerve disease.
Despite promising signs in earlier, shorter studies, researchers found patients who took capsules containing tetrahydrocannabinol (THC), a key active ingredient in cannabis, fared no better than those given a placebo.
Damning research: Cannabis does not slow the progression of multiple sclerosis, a large-scale study has concluded
In the study known as Cupid – cannabinoid use in progressive inflammatory brain disease – MS patients were assessed on both a disability scale administered by neurologists and another based on their own reporting.
Lead researcher John Zajicek said: 'Overall the study found no evidence to support an effect of THC on MS progression in either of the main outcomes.'
The results from the study, which was funded by the Medical Research Council, were presented at the Association of British Neurologists' annual meeting in Brighton today.
Cannabis contains more than 60 different cannabinoids, of which THC is thought to be the most active, and many MS patients have long said the drug helps them cope with the effects of the disease.
Drug companies, too, have been interested in cannabis as a medicine.
GW Pharmaceuticals, working with Bayer and Almirall, recently started selling an under-the-tongue cannabis spray called Sativex to relieve spasticity..
The research is a blow to hopes that the drug could provide long-term benefits for patients with the debilitating nerve disease
David Nutt, professor of neuropsychopharmacology at Imperial College London, who was not involved in the latest research, said the study's failure did not mean cannabis had no role in helping MS patients.
He said: 'It would be wrong to interpret these preliminary findings to mean that cannabis does not achieve its licensed use.
'Cannabis is not licensed for limiting disease progression, it is licensed for dealing with spasticity and pain.'
Professor Zajicek's study did find some evidence to suggest a beneficial effect in less disabled patients, but because this was seen in only a small group of people it was unclear how strong the effect was.
The overall study population also experienced slower disease progression than had been expected, making it more challenging to detect any treatment effect, the researchers added.
MS is a disease in which immune system cells destroy the myelin sheath that protects the nerve cells in the brain and spinal cord.
The most common type is relapsing remitting MS, affecting around 85 per cent of patients at the time of diagnosis. Several drugs are available to treat this stage of the disease, including injections of beta-interferons and a new pill from Novartis called Gilenya.
Secondary progressive MS comes later and involves a sustained build up of disability.