The authors of this review paper are representatives of Saint James School of Medicine in Illinois and School of Natural Sciences at Kean University 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 Biomedicines on February 24 and analyzes 28 different studies in relation to multiple sclerosis. These final studies were chosen from a pool of 119 articles that were eligible for consideration in this review.
Multiple sclerosis symptoms often include fatigue, mobility impairment, speech impairments, chronic neuropathic pain, anxiety, depression, and a range of other 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.”
Fourteen of the 28 studies involved using animal models while exploring 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. The authors determined that the studies were promising but cannot replace tests conducted on human subjects. “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.”
Nine of the studies analyzed the efficacy of cannabis on muscle spasms, five evaluated cannabis and pain, three examined lower urinary tract function, and three explored sleep quality.
The authors of this review conclude that, similarly to most other research initiatives involving cannabis, while there is promising evidence that cannabis can help treat multiple sclerosis and a variety of symptoms, more studies are necessary. “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.”
The National MS Society states that there are 2.3 million people who suffer from multiple sclerosis worldwide, and that over one million people suffer from the condition in the US. 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 the rights of people with MS to work with their health care provider to access cannabis for medical purposes in accordance with legal regulations in those states where such use has been approved. 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.”