MELVILLE, N.Y. — Scientists at the Harvard School of Public Health have found that young people who have a strong immune response to the Epstein-Barr virus, the most common culprit in triggering mononucleosis, are at double the risk for developing multiple sclerosis in adulthood.
Multiple sclerosis is an autoimmune disease of the central nervous system, the brain, spinal cord and optic nerves. The immune system sends out soldiers that damage the protective covering, or insulation, called myelin, around nerve cells. The result: The electrical impulses that run through the insulated wires can no longer send the correct message.
Patients experience a variety of symptoms, including fatigue, partial paralysis, numbness, coordination and vision problems and cognitive deficits.
Recently, many researchers have searched for specific viral causes. In the latest Harvard study, by Dr. Alberto Ascherio, an associate professor of nutrition and epidemiology, 42 people with multiple sclerosis were identified through the Kaiser Permanente Northern California health plan. Twenty years ago, Kaiser scientists took blood samples from 100,000 clients. The agency also maintains extensive medical records from all patients in its system.
The Harvard scientists selected 84 people without multiple sclerosis to compare with those who had the disease. They analyzed the blood samples for antibodies to Epstein-Barr and other viruses.
Patients with multiple sclerosis had antibody levels four times higher than those of people without the disease. People with these strong immune responses (and hence higher antibody levels) were at twice the risk of developing MS.
The study was published in the current Archives of Neurology. Though there is no treatment for Epstein-Barr, nor a way to prevent exposure to it, the finding may stimulate scientists to develop a vaccine against the virus.
"This is another strong study that implicates Epstein-Barr virus and multiple sclerosis," said Dr. Patricia K. Coyle, acting chairwoman of neurology at Stony Brook University Hospital and director of the hospital's multiple sclerosis center. "It is almost as if the virus sets the stage for the development of multiple sclerosis."
Neither Coyle nor Ascherio thinks the virus actually enters the brain. Instead, the strong immune response in genetically susceptible individuals could cross-react with brain substances, allowing the brain to attack its own myelin.
Coyle said a recent large analysis on mononucleosis also found it was a risk factor for multiple sclerosis. There is a two- to threefold higher risk in people who have had mononucleosis, Ascherio said.
"This is important because it may give us insight into why MS occurs," Coyle said.