Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS) that affects millions of people worldwide. It is characterized by autoimmune-mediated, demyelinating, and neurodegenerative processes that lead to neurological attacks and accumulating disability over time. The disease causes demyelination, axonal and neuronal loss in various neural pathways of the CNS, resulting in cognitive, sensory, and motor problems such as pain and spasticity. In contrast, amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that results from the selective damage of motor neurons in the spinal cord, brainstem, and motor cortex. The pathogenesis of ALS includes chronic inflammation, excitotoxic damage, oxidative stress, and protein aggregation.

Based on pre-clinical studies, THC, CBD, and nabiximols have shown potential in improving symptoms associated with multiple sclerosis (MS), such as tremors, spasticity, and inflammation. Clinical studies indicate that cannabis (with limited evidence) and specific cannabinoids such as dronabinol, nabiximols, and THC/CBD may provide some relief for symptoms experienced in MS and spinal cord injury (SCI), including pain, spasticity, spasms, sleep, and bladder dysfunction. Although pre-clinical studies have shown that certain cannabinoids may slightly delay disease progression and prolong survival in animal models of amyotrophic lateral sclerosis (ALS), the evidence from a limited number of clinical studies is mixed.

According to a systematic review of existing clinical trial data, cannabinoids (e.g., THC, CBD, nabiximols) are likely effective for reducing patient-reported and objective measures of spasticity in selected neurological disorders, including MS. They are also likely effective for reducing central pain or painful spasms and probably effective for reducing the number of bladder voids per day. However, they are probably ineffective for reducing bladder complaints and possibly ineffective for reducing tremor.

In contrast, a more recent systematic review and meta-analysis of 28 randomized controlled trials (RCTs) with over 2,000 participants reported that cannabinoids (smoked cannabis, nabiximols, nabilone, dronabinol, CBD, THC, levonontradol, ajulemic acid) were associated with improvements in spasticity, although this failed to reach statistical significance. Specifically, cannabinoids were associated with a greater average improvement on the Ashworth scale for spasticity, as well as a greater average improvement in spasticity assessed using numerical rating scales. Moreover, the average number of patients reporting an improvement on a global impression of change score was greater with nabiximols than placebo.

While the methodologies, approaches, and inclusion/exclusion criteria of these two systematic reviews differ, they both suggest that cannabis and cannabinoids are associated with some measure of improvement in spasticity, spasms, and pain in selected neurological disorders, including MS and spinal cord injury/disease.

Reference information: https://www.canada.ca/en/health-canada/services/drugs-medication/cannabis/information-medical-practitioners/information-health-care-professionals-cannabis-cannabinoids.html#a4.1