Their finding may help test the effectiveness of new treatments for these types of MS.
The investigators used specialized brain scans to examine the brains of hundreds of MS patients and identified dark-rimmed spots that represent ongoing inflammation (chronic active lesions) that may be associated with more aggressive MS.
"We found that it is possible to use brain scans to detect which patients are highly susceptible to the more aggressive forms of multiple sclerosis. The more chronic active lesions a patient has, the greater the chances they will experience this type of MS," said senior study author Dr. Daniel Reich. He is a senior investigator at the U.S. National Institute of Neurological Disorders and Stroke (NINDS).
"We hope these results will help test the effectiveness of new therapies for this form of MS and reduce the suffering patients experience," Reich added in a NINDS news release.
MS occurs when the immune system mistakenly attacks myelin, a protective coating around nerve cells in the brain and spinal cord. Magnetic resonance imaging (MRI) is often used to diagnose MS because it can reveal brain lesions caused by MS.
While some lesions completely or partially heal, others remain and some expand for many years. But it was difficult to detect these chronically inflamed lesions. In 2013, Reich's team discovered that a high-powered, 7-tesla MRI scanner could accurately identify chronic active lesions by their darkened outer rims.
"Figuring out how to spot chronic active lesions was a big step" because it "allowed us to then explore how MS lesions evolved and whether they played a role in progressive MS," said Dr. Martina Absinta, a postdoctoral fellow in Reich's lab.
The study was published Aug. 12 in the journal JAMA Neurology.
"Our results point the way towards using specialized brain scans to predict who is at risk of developing progressive MS," Reich said.
He pointed out that these spots reveal ties to the brain's immune system.
"Our results support the idea that chronic active lesions are very damaging to the brain," Reich said. "We need to attack these lesions as early as possible. The fact that these lesions are present in patients who are receiving anti-inflammatory drugs that quiet the body's immune system also suggests that the field of MS research may want to focus on new treatments that target the brain's unique immune system - especially a type of brain cell called microglia."
More than 2 million people worldwide have MS. There is currently no cure.