A commonly prescribed treatment for multiple sclerosis (MS) is associated with increased levels vitamin D, researchers have found, potentially altering the future treatment of the disease.
There is no cure for MS but medications can ease the symptoms. Around 60% of MS patients with the relapsing-remitting form of the disease are prescribed the drug interferon-beta, which reduces the frequency of relapse.
The team of Australian scientists used data from the Tasmanian MS Longitudinal Study, which followed 178 people with MS living in southern Tasmania. Based on bi-annual vitamin D test data, they found that patients taking interferon-beta had three-times higher levels of vitamin D from the equivalent level of sun exposure as those who weren’t taking the drug.
The findings are published in the journal Neurology.
Co-lead author Dr Steve Simpson Jr from the Menzies Research Institute Tasmania said vitamin D was known to be associated with MS but scientists still didn’t know how interferon-beta worked.
“There are a lot of theories, most involving the immune system. Vitamin D itself is also a modulator of the immune system: it depresses inflammatory responses and enhances anti-inflammatory responses. It may be that by enhancing levels of vitamin D in circulation, interferon-beta may realise its effects on the immune system that account for its therapeutic effects in MS,” he said.
Rates of MS vary widely across Australia and are seven times higher than in Tasmania than northern Queensland.
“One of the environmental factors which is thought to explain this gradient is the decrease in winter ambient UV at higher latitudes like Tasmania,” said Dr Simpson.
“Since vitamin D is largely produced from the sun in populations of European heritage, the lower levels of winter UV result in a majority of the population being vitamin D deficient in winter, increasing MS risk.”
Associate Professor David Booth from the University of Sydney’s Westmead Millennium Institute for Medical Research said the study opened the door to further research into the link between vitamin D and interferon-beta.
“This is a first observation and doesn’t show any causative link between interferon and vitamin D,” he said. The findings would need to be replicated, then they could potentially be used to predict which patients would respond to interferon.
“One of the big things in MS is there are so many different drugs you can now choose from. Interferon was the first of the drugs to be used and it’s got quite a good safety profile and not much in the way of adverse reactions, not like some of the other drugs,” he said.
“But it doesn’t work particularly well compared with other drugs – you get about a 30% reduction in relapse rates, whereas some of the others get up to 70% or 80%, but they’ve got adverse reactions.
"If you could find a way to use interferon so the reduction in relapse was commensurate with the other drugs but didn’t have any of the adverse reactions, that would be fantastic.”