While the cause of multiple sclerosis (MS) is still not known, advances in treatment options and new understanding about the disease have been especially brisk in the past few years, researchers say.
As a result, the future for the 400,000 Americans with the chronic, sometimes disabling disease may soon be brighter.
In MS, the body turns on itself, attacking myelin, the fatty substance protecting nerve fibers in the central nervous system. That leads to damaged nerve fibers (axons), which hinders nerve impulses from traveling to and from the brain and spinal cord. As a result, numbness, limb weakness, and blurred vision occur. Most patients with MS are diagnosed initially with a form called relapsing-remitting, involving flare-ups followed by remissions.
Four MS experts, consulted by WebMD, agree that the past two or three years have seen noteworthy advances in many areas, including:
- New understandings about the genetics of the disease
- More drug treatment options, including oral medications expected soon
- New techniques to repair the damage caused by MS
- New information about the potential causes of the disease
Here are summaries of some recent findings, including updates from the Nancy Davis Foundation for Multiple Sclerosis, which funds basic research through its Center without Walls, a network of research programs.
MS: The Genetic Underpinnings
Researchers have discovered a number of genes in recent years that may make people more susceptible to multiple sclerosis. While the genes do not cause MS, they make people more likely to develop MS when exposed to certain environmental factors or viruses, experts say.
''Genetics [research] is really going at a fast rate now," says Patricia O'Looney, PhD, vice president of biomedical research at the National Multiple Sclerosis Society.
Currently, researchers have identified 34 possible genetic factors, O'Looney says. More are expected to be identified. At least 50 are expected, says Leslie Weiner, MD, professor of molecular microbiology and immunology at the University of Southern California Keck School of Medicine, Los Angeles.
"There are probably multiple genes that contribute," says Jeffrey Cohen, MD, the director of clinical therapeutics at the Cleveland Clinic Foundation's Mellen Center for Multiple Sclerosis Treatment and Research. Some may contribute to the risk of developing MS, he says, and some to how the disease progresses.
Eventually, MS researchers hope genetics will allow doctors to identify people at high risk for the disease and intervene with treatment at very early stages of MS -- perhaps even before symptoms appear.
MS: Drug Treatment Options Grow
Eight medications are approved by the FDA to reduce the frequency of relapses and possibly slow the progression of MS. These drugs are called disease-modifying therapies. So far, most MS disease-modifying drugs must be injected or administered intravenously. The newest drug, Gilenya (fingolimod), approved by the FDA in 2010, is the first disease-modifying MS drug that can be taken orally.
Fingolimod has been shown in studies to reduce the relapse rate of MS by up to 54% compared to placebo. However, it has serious side effects, with possible heart, lung, and eye toxicity and increased risk of infection. Patients must be closely monitored, and regular eye exams are advised.
Other new drugs for multiple sclerosis that can be taken orally are in clinical trials. If approved, they may offer a welcome end to injections for some patients.
Approval of these drugs will be just the beginning, predicts Cohen, who has been a consultant and researcher for Novartis, which makes fingolimod, as well as for other pharmaceutical companies. He speculates that eight or 10 new medications for MS will become available over the next three to five years, as basic research comes to fruition and scientists discover medicines approved for other diseases that also may help MS patients.
MS: Repairing the Damage
Restoring nervous system function is a hot focus in MS research.
Traditionally, experts believed that once myelin was destroyed, ''that was it," says O'Looney. "Now we know there is the potential for remyelination."
A major research goal is to figure out how to replace the cells that make myelin, which are lost in MS patients. Researchers have had some success using human embryonic stem cells to generate myelin-producing cells. They are studying the effectiveness of adult stem cells. Growth factors (substances that affect the growth of a cell) are also being studied for their ability to repair myelin-producing cells.
The focus has also moved beyond just the myelin to the nerve fibers or axons. ''We know now there is a dynamic interaction between the myelin and the axons," says Peter Calabresi, MD, a professor of neurology at Johns Hopkins University and a leader in this nervous system repair effort.
''The myelin tells the axon (nerve fibers) to be more or less functioning,'' Calabresi says. A better understanding of the interaction, he says, will hopefully help scientists figure out how to rescue the axons and restore the myelin. Calabresi has received grants and consulting fees from Biogen Idec, which makes MS drugs.
Identifying and Treating Disparate Causes of MS
In the past few years, vitamin D has been the focus of many MS researchers. Some studies have found evidence of an interaction between low vitamin D and a common MS genetic variant, called DRB1*1501. The combination appears to boost the risk of getting the disease.
Low vitamin D is viewed by some experts as a potential environmental trigger. "About 35% of all North Americans have low vitamin D," Weiner says. There is some evidence, he says, that MS patients have even lower vitamin D than the general population.
''If you measure vitamin D during an acute [MS] attack, the vitamin D levels go way down," Weiner says. When a patient is in remission, the levels are closer to normal, says Weiner, who has received grants from Teva for basic science research and consulted for Biogen Idec and Merck Serono.
''Clinically, we treat everyone the same," Weiner says. ''We need to think more broadly." MS, he says, maybe caused by multiple factors -- low vitamin D in one person, something else in another person, and understanding the various causes could lead to targeted treatments.
Perhaps the most controversial idea about the potential cause of MS is one proposed by Paolo Zamboni, MD, of the University of Ferrara. He suggests that an abnormality in blood drainage may contribute to the nervous system damage of MS. The condition, called chronic cerebrospinal venous insufficiency or CCSVI, may cause changes in blood flow patterns within the brain, in turn causing brain tissue injury and neuron degeneration, he proposes.
The ''fix" is inserting a tiny balloon or stent in the vessel to improve blood flow. The technique continues to be studied by researchers, including scientists at Stanford University and the University of Buffalo.
But many MS experts are skeptical. ''I can't see how anyone can claim this is what is causing MS," Calabresi tells WebMD. In the ongoing Buffalo research, more than half of MS patients were found to have the condition. But so did more than 20% of the healthy patients, Calabresi says.