Interferon delays multiple sclerosis

In some people who show early-warning signs of multiple sclerosis, the drug interferon-beta-1a seems to delay or even prevent the disease from becoming full-blown, researchers report in the Sept. 28 New England Journal of Medicine.

The signs of multiple sclerosis (MS) can include blurry vision, dizziness, loss of coordination, bladder problems, and numbness in the face, lower trunk, or limbs. Not everyone having such symptoms ultimately develops MS. Physicians arrive at a diagnosis of the disease only after a second episode of symptoms, which can come months or years after the first.

In the mid-1990s, the Food and Drug Administration cleared interferon-beta-1a for patients already diagnosed with MS. Whether the drug could help a person who had had only one occurence of symptoms remained unclear, however.

Starting in 1996, a group of researchers tracked 383 people in the United States and Canada who had had one episode of troubling symptoms, giving roughly half of the study participants weekly injections of interferon-beta-1a and the others an inert substance. During the trial, participants and researchers were unaware of which shots contained medication.

Whereas 73 of the 193 untreated people developed MS during the 2-year study, only 47 of the 190 patients getting interferon-beta-1a did, says study coauthor Lawrence D. Jacobs, a neurologist at the State University of New York in Buffalo. On average, patients who developed MS despite interferon-beta-1a therapy did so later than those in the untreated group.

In recent years, magnetic resonance imaging has improved the diagnosis of MS. Scans can show a steady deterioration of the brain even before patients show many outward signs of disease. But not everyone who has symptoms gets magnetic resonance imaging, Jacobs says.

Multiple sclerosis is a chronic inflammatory disease that causes brain shrinkage. The condition strips away the protective sheaths surrounding cells in the central nervous system and brain and causes fluids to leak through the membrane that surrounds the brain. These changes cause the initial symptoms and the eventual muscle weakness, cognitive decline, and other debilitating conditions that characterize MS. Roughly half of all MS patients need help walking within 15 years of its onset.

By 1998, the medical committee overseeing the interferon-beta-1a study stopped the trial and made the drug available to all participants, even before the researchers had analyzed all the data. On the basis of those early findings and improvements in brain scanning, some physicians are now prescribing interferon-beta-1a for patients with early signs of MS, Jacobs says.