This story was broadcast on the BBC news today
Cannabis study encouraging for MS
By Paul Rincon
BBC News Online science staff, at the BA festival
The drugs contain active compounds extracted from the plant
The biggest UK study of cannabis-based drugs has shown evidence for a long-term benefit in easing the symptoms of multiple sclerosis (MS).
"There is some evidence of a long-term effect," Dr John Zajicek, who heads the trial, confirmed to the BA Festival of Science at Exeter University.
He also said the data so far "were consistent" with the idea the drugs could arrest nerve death in sufferers.
He was presenting results that update a study published in The Lancet last year.
This 15-week research project revealed patients using cannabinoid compounds could find relief from some of the painful symptoms of MS.
But an analysis of the data suggested there was little reduction in spasticity among the research subjects - one of the key tests used to assess the drugs.
Spasticity refers to feelings of stiffness and a wide range of involuntary muscle spasms or sudden movements.
Speaking at the annual British Association meeting, Dr Zajicek, from the Peninsula Medical School in Devon, said this assessment might have been premature.
Longer-term monitoring, he said, had now shown patients experiencing significant improvement in this area.