Recently, a UCSF-led research study has identified an over-the-counter antihistamine drug as a treatment for multiple sclerosis patients. The researchers, led by physician-scientist Ari Green, MD, who together with neuroscientist Jonah Chan, PhD, first identified clemastine as a potential MS therapy, used MRI scans to study the drug’s impact on the brains of 50 participants in a clinical study.
Myelin, the protective covering around nerve fibers, is lost by patients with multiple sclerosis. By causing delays in nerve signals, this myelin loss causes symptoms such as rigidity and stiffness, visual loss, cognitive delay, and other problems. Water cannot travel as freely between brain cells as it does when it is trapped between the thin myelin layers that surround nerve fibers. By measuring the myelin water fraction, or the ratio of myelin water to the overall water content in brain tissue, imaging specialists were able to examine the difference in myelin levels before and after the medicine was provided.
In their study, which was released on May 8, 2023 in PNAS, the researchers discovered that clemastine treatment resulted in moderate increases in myelin water, a sign of myelin repair, in MS patients. Additionally, they demonstrated that myelin recovery could be monitored using the myelin water fraction technique when applied to the appropriate brain regions.
“This is the first example of brain repair being documented on MRI for a chronic neurological condition,” said Green, medical director of the UCSF Multiple Sclerosis and Neuroinflammation Center and a member of the Weill Institute for Neurosciences. “The study provides the first direct, biologically validated, imaging-based evidence of myelin repair induced by clemastine. This will set the standard for future research into remyelinating therapies.”
Clemastine was given to the first group of MS patients for the first three months of the study, and to the second group just for months three through five. Both groups were participants in the ReBUILD experiment. The researchers discovered that the myelin water percentage increased in the first group after participants got the medication and continued to grow after clemastine use was discontinued. When individuals took clemastine, the myelin water fraction in the second group rebounded after decreasing during the study's initial phase under the placebo.
The results support those of a prior trial involving 50 of the same patients, which revealed that the allergy drug decreased delayed nerve transmission, thereby relieving many symptoms that come along with multiple sclerosis due to lack of myelin
Works Cited
“Clemastine.” MS Society, https://www.mssociety.org.uk/research/explore-our-research/emerging-research-and-treatments/explore-treatments-in-trials/clemastine. Accessed 20 June 2023.
Green, Ari J. “Clemastine fumarate as a remyelinating therapy for multiple sclerosis (ReBUILD): a randomized, controlled, double-blind, crossover trial.” The Lancet, vol. 390, no. 10111, 2017, pp. 2481-2489. National Journal of Medicine, https://pubmed.ncbi.nlm.nih.gov/29029896/. Accessed 20 June 2023.
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