A Review of the Evidence for Medical Cannabis and Multiple Sclerosis 

Multiple Sclerosis (MS) is a chronic, inflammatory, neurodegenerative disorder that affects the Central Nervous System (CNS). It is characterised by focal demyelinated lesions that are expressed in diverse locations throughout the CNS. As such, the disorder can cause a broad range of symptoms as well as temporary or permanent neurological deficit. There are four distinct clinical courses of MS: relapsing remitting MS, secondary progressive MS, primary progressive MS and progressive relapsing MS. Each of these courses affects disease progression and potential associated disability in different ways.  

While there are many symptoms associated with MS, the most common indication for symptom management is pain, which affects up to three-quarters of patients. Other common symptoms include sensory and motor symptoms, and cognitive impairment. Multiple Sclerosis can have a significant effect on physical health, psychological wellbeing and both social and economic health. As such, patients with MS often experience a significant loss to quality of life.  

Current treatments for MS include disease modifying therapies, the use of corticosteroids to treat MS relapses and therapies to address symptoms such as those listed above. While there are a number of treatment options available, evidence for their efficacy is still limited. As a result, many patients and clinicians are interested in the potential of new therapy options that could prove beneficial. One of these therapies is medical cannabis. 

While MS patients in the UK can legally access medical cannabis, evidence shows that many are unaware of this fact. Furthermore, a 2019 survey found that up to 20% of UK-based MS patients self-medicate with illicitly sourced cannabis products. These findings highlight the need for more effective methods of raising public awareness around the potential and legality of medical cannabis for Multiple Sclerosis. With this in mind, a team of researchers recently conducted a review of the literature relating to the efficacy and safety of medical cannabis in patients with MS. 

Medical Cannabis and Multiple Sclerosis 

The UK government introduced the legalisation of medical cannabis in November 2018 for a small number of conditions. One of these conditions is spasticity associated with MS. Current guidelines by the UK’s National Institute for Health and Care Excellence recommend that doctors can offer a 4-week trial of THC:CBD (Sativex®) spray for moderate to severe spasticity in adults with multiple sclerosis if other first-line therapies have proven ineffective. Unlicensed medical cannabis preparations can only be started by specialist clinicians, meaning that many patients can only access medical cannabis through private clinics such as Sapphire Medical Clinics, unless they meet the criteria set out by NICE. 

Spasticity 

Spasticity is characterised by the involuntary contraction of muscles and increased muscle tone caused by the development of lesions on the descending motor pathways of the central nervous system. Sativex® has been extensively evaluated for this use in randomised controlled trials. A systematic review concluded it was associated with a 2.5 times increased likelihood of an improvement for MS-associated spasticity.   

However, it is noted that there remains a paucity of evidence on the use of other cannabis-based medicines for MS-associated spasticity. The article’s authors from Sapphire Medical Clinics recommend that future research should also evaluate other medical cannabis formulations – particularly in patients who are unable to tolerate adverse events associated with Nabiximols. 

Pain 

As mentioned earlier, pain affects up to three-quarters of MS patients, making it a significant area of interest for symptomatic MS treatments. MS pain may can be caused by several different aetiologies. For example, central neuropathic pain and paraesthesia may be caused by the development of lesions on the sensory tracts within the spinal cord and brainstem. Musculoskeletal pain associated with spasticity and tremors is also common and may lead to secondary pain in patients who require mobility aids. 

The researchers note that high-quality clinical data on pain outcomes for people with MS is currently limited; however, a review by Filippini et al (2022) found improvements associated with medical cannabis when compared to placebo. Furthermore, a meta-analysis found that non-inhaled cannabis-based medicines were associated with a 10% increase in the number of patients who experienced a clinically significant reduction in their pain. These findings were mirrored by those of the UK Medical Cannabis Registry, which identified “improvements in patient reported outcome measures that evaluated pain interference and severity, as well as neuropathic pain”. 

Quality of Life and Mood Disorders 

Studies have identified a higher prevalence of mood and anxiety disorders among patients with MS when compared to the general population. This increased prevalence is believed to be linked to the burden of living with a chronic progressive disease and increased risk of disability, as well as potential side effects associated with some treatments.  

Analysis from the UK Medical Cannabis Registry had previously shown a reduction in anxiety for those with generalised anxiety disorder under the care of Sapphire Medical Clinics.  

The various physical, physiological, and psychological symptoms associated with MS can have a significant impact on patients’ quality of life. Long-term real-world evaluations have demonstrated that medical cannabis was associated with changes in health-related quality of life for several conditions. However, there remains little high-quality evidence in the case of Multiple Sclerosis. 

Conclusions 

The authors of this review conclude that there is significant evidence to suggest that medical cannabis is generally well-tolerated by most patients – including patients with MS. Furthermore, there is promising evidence to suggest surrounding medical cannabis and MS. Nonetheless, it is also noted that there remains a need for further high-quality controlled trials to yield the evidence needed to further support the use of medical cannabis in MS.