Review of 28 studies suggests role for CBD and THC as therapy for MS but evidence base needs to be stronger.
While cannabidiol (CBD) and A9-tetrahydrocannabinol (Δ9-THC) can help ease MS pain, spasticity, and other symptoms, better human and animal studies are needed, according to new research.
Rana Zeine M.D., Ph.D.,an adjunct professor of biology at Kean University in Union, New Jersey, and colleagues reviewed 28 human and animal studies involving the use of CBD and/or to treat MS symptoms. They reported their findings in an article published in Biomedicines.
The medical marijuana studies conducted between 2007 and 2021 demonstrated, with a moderate certainty of evidence, that add-on therapy with 1:1 CBD/THC cannabinoid oromucosal spray mixtures is effective within a narrow therapeutic window to modestly improve primarily subjective measures of spasticity, pain, and bladder- and sleep-related quality of life in MS patients, they wrote.
Some benefits are maintained beyond six to 12 months, but others waned with prolonged use of the CBD/THC spray.
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, according to Zeine.
There are also promising benefits of cannabis use and medical marijuana for relief of neurologic symptoms in patients with movement disorders, including Parkinson’s disease and Huntington’s disease.
Oral CBD has been used for the treatment of drug-resistant seizures in children with tuberous sclerosis.
In 2018, the FDA approved Epidiolex,a CBD product, as a treatment for seizures associated with two rare and severe forms of epilepsy, Lennox-Gastaut syndrome and Dravet syndrome.
However, in order to increase confidence in the efficacy of medical marijuana as an add-on therapy in MS, higher-quality, multi-year, randomized, double-blind, placebo-controlled clinical trials are needed, the authors wrote.
Scientists should also conduct more animal studies that specifically examine the effects of combining 1:1 CBD and THC for MS. “There is strong evidence from animal studies that remyelination and improved motor function is possible,” they said.
In addition, radiological studies would be “extremely valuable” as follow-up measures to evaluate remyelination because precise associations have been described between different types of central nervous system (CNS) pathology and MRI findings in MS.
Some participants drop out of clinical studies because they don't experience any benefits, and they are labeled “nonresponders,” Zeine told Managed Healthcare Executive®.
“But this may be because the healing in the brain needs more time to develop new myelin, new mature oligodendrocytes, new neurons, and properly functioning synapses,” Zeine said.
"So, the goal is to allow sufficient time to induce neuroprotection (to preserve neurons and their axons), oligodendrocyte protection from damage, maturation of progenitors to replace the lost neurons and the dead oligodendrocytes, remyelination, and restoration of neurophysiologic function to a level that the patients can notice as improvement in their symptoms,” she added.
Some MS patients also quit clinical studies because of the side effects, particularly cognitive slowing or dizziness that interfere with their activities of daily living, the authors wrote. As a result, new formulations need to be designed and tested.