Washington: A new study has found no evidence of a cannabis constituent in the progress of multiple sclerosis.
The first large non-commercial clinical study to investigate whether the main active constituent of cannabis (tetrahydrocannabinol or THC) is effective in slowing the course of progressive multiple sclerosis (MS), shows that there is no evidence to suggest this; although benefits were noted for those at the lower end of the disability scale.
The CUPID (Cannabinoid Use in Progressive Inflammatory brain Disease) study was carried out by researchers from Plymouth University Peninsula Schools of Medicine and Dentistry.
CUPID enrolled nearly 500 people with MS from 27 centres around the UK, and has taken eight years to complete.
People with progressive MS were randomised to receive either THC capsules or identical placebo capsules for three years, and were carefully followed to see how their MS changed over this period.
The two main outcomes of the trial were a disability scale administered by neurologists (the Expanded Disability Status Scale), and a patient report scale of the impact of MS on people with the condition (the Multiple Sclerosis Impact Scale 29).
Overall the study found no evidence to support an effect of THC on MS progression in either of the main outcomes.
However, there was some evidence to suggest a beneficial effect in participants who were at the lower end of the disability scale at the time of enrolment but, as the benefit was only found in a small group of people rather than the whole population, further studies will be needed to assess the robustness of this finding.
One of the other findings of the trial was that MS in the study population as a whole progressed slowly, more slowly than expected.
This makes it more challenging to find a treatment effect when the aim of the treatment is to slow progression.
The study is published in The Lancet Neurology.