For decades, researchers seeking to develop new treatment options for multiple sclerosis (MS) believed that it was primarily a disease of the brain’s white matter, but recent studies have highlighted that grey matter plays an important role as well. For instance, grey matter loss, known as atrophy, may be seen in early stages of the disease and is associated with worsening symptoms.
As part of this year’s efforts to raise awareness of the disease during World MS Day on May 30, Dr. Robert Zivadinov, professor of Neurology and director of the Buffalo Neuroimaging Analysis Center and Center for Biomedical Imaging at Clinical Translational Science Institute at the University of Buffalo, explains researchers’ evolving understanding of the role of grey matter damage in MS.
MS was previously considered to affect white matter primarily. How has that understanding evolved to include grey matter?
“About 15 years ago, improved imaging techniques revealed that large areas of grey matter were affected in patients. This evidence helped explain why some patients had such severe disease but relatively few damaged areas in the white matter, known as lesions.”
Are there specific regions of grey matter that are affected by MS?
“Not all parts of the grey matter are equally affected. There’s definitely significant involvement of the cortical layers of the brain’s grey matter, which is linked to symptoms such as fatigue, cognitive changes and memory loss.
“The deep grey matter is also involved in MS as well, and in particular the thalamus, which relays motor signals and regulates things like consciousness, sleep and alertness.”
“Some studies have found that grey matter atrophy correlates with disability, cognitive impairment and disease progression better than white matter.”
What do researchers know about the connection between the loss of grey matter, cognitive dysfunction, disability and MS progression?
“Many studies have found links between grey matter damage with both physical and cognitive impairment in patients with MS, including symptoms such as muscle control, sensory perception and memory. Some studies have found that grey matter atrophy correlates with disability, cognitive impairment and disease progression better than white matter lesions do.
“Studies also suggest that grey matter lesions occur rather early on, particularly in relapsing-remitting MS, even before white matter lesions appear. It could very well be a potential marker for predicting disease progression.”
What is preventing it from becoming a more useful predictor of disease progression?
“Grey matter lesions are less pronounced than white brain lesions, so doctors have difficulty seeing them on typical MRIs. Instead, we have to use advanced, highly sensitive MRI techniques to measure changes in grey matter, but those techniques aren’t available everywhere. They require specialized equipment and expertise that is typically only found in academic research centers. That is one reason why grey matter atrophy has had limited use in the clinic.”
What do we still not understand about grey matter atrophy in people with MS?
“We still don’t understand what causes the damage. Grey matter atrophy is associated with several genetic, viral and environmental risk factors, but we haven’t pinpointed the mechanisms yet.”
What can be done to reduce the risk of damage to grey matter?
“That’s the holy grail. Most MS trials weren’t necessarily designed to answer that question. We are going to have to change the design of MS trials. Instead of only using MRIs of white matter lesions as an endpoint, we’ll need more sensitive imaging techniques to monitor grey matter changes over time as well.”
To learn more about how MS affects the brain over a lifetime, read “How Multiple Sclerosis Affects the Brain and CNS.”
Dr. Robert Zivadinov is a paid consultant for Celgene.