This review paper was written by representatives of Saint James School of Medicine, Illinois and Kean University’s School of Natural Sciences in New Jersey. Their review paper, “Neurological Benefits, Clinical Challenges, and Neuropathologic Promise of Medical Marijuana: A Systematic Review of Cannabinoid Effects in Multiple Sclerosis and Experimental Models of Demyelination,” was published in the journal BiomedicinesOn February 24, the review analyzed 28 studies related to multiple sclerosis. This review considered 119 articles.

Multiple sclerosis symptoms include fatigue, mobility impairments speech impairments chronic neuropathic discomfort, anxiety, depression and many other side effects. In their review, researchers state that patients are dissatisfied with current treatments available for their condition, which motivates researchers “to search for adjunctive remedies in the hope of preventing breakthrough relapses and worsening of disability.” 

14 of 28 of the 28 studies used animal models to study the effects of cannabis. Overall, the authors of the study determined that “The experimental results combined adequately demonstrate that cannabinoid treatments are effective” with diminishing a variety of symptoms. Although the results were encouraging, they cannot be considered as a replacement for human tests. “While internal validity was very good in the preclinical studies because experiments were well designed and well controlled, the external validity of animal studies is less certain due to differences in the cannabinoid systems between species that may affect safety, dose responses, tolerability, and homeostasis.”

The researchers also evaluated 14 human-based studies, which utilized Sativex®, which is a cannabis-based oral spray approved for multiple sclerosis in the EU, UK, and Canada, but not yet in the US. “The growing body of moderate-quality evidence for the safety and efficacy of cannabinoid treatment using 1:1 THC/CBD mixtures has led to its approval in some countries for the management of spasticity, pain, and bladder dysfunction in MS,” the authors wrote. “Our assessments agree with others, finding that the magnitudes of effects on short-term neurological outcomes in MS patients are either small, limited, or moderate, and that the benefits are more easily detected by subjective rather than objective measures.”

The efficacy and safety of cannabis for muscle spasms was examined in nine of these studies. Five of those evaluated pain and cannabis, while three compared it to the lower urinary tract. Three of the three other studies looked at sleep quality.

This review concluded that there was promising evidence to suggest that cannabis could be used in multiple sclerosis treatment. However, further research is needed. “Future studies are recommended to investigate the cellular and molecular mechanisms of cannabinoid effects on MS lesions and to evaluate whether medical marijuana can accelerate remyelination and retard the accrual of disability over the long term.”

According to the National MS Society, there are approximately 2.3 million multiple sclerosis sufferers worldwide and more than one million in America. The organization’s stance on medical cannabis is supportive, and also calls for more research to bolster evidence for cannabis as a multiple sclerosis treatment. “The [National MS]Society supports MS sufferers’ right to consult their doctor to get medical marijuana in accordance to the laws in each state. In addition, the Society supports the need for more research to better understand the benefits and potential risks of cannabis and its derivatives as a treatment for MS and its symptoms.”