Active cannabis ingredient doesn’t slow progression of multiple sclerosis

Washington - The main active constituent of cannabis  (tetrahydrocannabinol or THC) is has no effect on the progression of multiple sclerosis, but people at the lower end of the disability scale of multiple scelerosis (MS) may be benefited, a study has revealed.

The CUPID (Cannabinoid Use in Progressive Inflammatory brain Disease) study was carried out by researchers from the Peninsula College of Medicine and Dentistry (PCMD), Plymouth University.

CUPID had enrolled nearly 500 people with MS from 27 centres around the UK, and the research took eight years to complete.

People with progressive MS were randomised to receive either THC capsules or identical placebo capsules for three years, and then 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 proof to support an effect of THC on MS progression in either of the main outcomes.

However, there were 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 made it more challenging to find a treatment effect when the aim of the treatment is that of slow progression.

As well as evaluating the potential neuroprotective effects and safety of THC over the long-term, one of the aims of the CUPID study was to improve the way that clinical trial research is done by exploring newer methods of measuring MS and using the latest statistical methods to make the most of every piece of information that was collected.

This analysis will continue for several months and the CUPID study will therefore provide important information about conducting further large-scale clinical trials in MS.

“To put this study into context: current treatments for MS are limited, either being targeted at the immune system in the early stages of the disease or aimed at easing specific symptoms such as muscle spasms, fatigue or bladder problems,” Professor John Zajicek, Professor of Clinical Neuroscience at PCMD, Plymouth University, said.

“At present there is no treatment available to slow the disease when it becomes progressive. Progression of MS is thought to be due to death of the nerve cells, and researchers around the world are desperately searching for treatments that may be ‘neuroprotective’. Laboratory experiments have suggested that certain cannabis derivatives may be neuroprotective.

“Overall our research has not supported laboratory based findings and shown that, although there is a suggestion of benefit to those at the lower end of the disability scale when they joined CUPID, there is little evidence to suggest that THC has a long term impact on the slowing of progressive MS,” he said.

Dr Doug Brown, Head of Biomedical Research at the MS Society said that currently there are no treatments for people with progressive MS to slow or stop the worsening of disability.

“While this study sadly suggests THC is ineffective at slowing the course of progressive MS, we will not stop our search for effective treatments. We are encouraged by the possibility shown by this study that THC may have potential benefits for some people with MS and we welcome further investigation in this area,” he added.

The preliminary results of CUPID were presented by lead researcher Professor John Zajicek at the Association of British Neurologists’ Annual Meeting in Brighton.