Over the past few decades, scientists have come to understand that the loss of brain tissue—categorized into grey and white matter—in people with multiple sclerosis (MS) is linked with disease worsening. But research is revealing that grey matter loss, in particular, may be closely associated with disability and cognitive impairment.
“Grey matter loss is one of the best predictors of disease progression in people with MS,” said Dr. John DeLuca, senior vice president for research and training at the Kessler Foundation. “Finally, we’re seeing data that may help us better understand the mechanisms that drive this disease.”
DeLuca is calling attention to the value of assessing grey matter and cognitive impairment in MS and what implications these findings may have in understanding the disease.
Grey Matter Loss Associated With MS Disability Progression
While researchers have known that grey matter loss is associated with long-term disability, a study published earlier this year has provided a more detailed picture of that connection.
The researchers looked at how specific patterns of grey matter loss were associated with disability progression in patients with MS using a standard MS disability scale (EDSS).
The researchers found the strongest relationship between disability progression and the loss of brain tissue in the thalamus, the largest area of deep grey matter, which transmits sensory information to other areas of the brain. In a post-hoc analysis of MRIs from 1,214 MS patients and 203 healthy controls, baseline thalamic volume loss increased risk of disability progression by 37 percent in relapsing MS.
“The research continues to provide more evidence that loss of grey matter is associated with increased disability,” he said. “And grey matter loss is seen most intensely in the thalamus of patients with MS.”
Cognitive Impairment Shouldn’t Take a Backseat to Disability
The new study makes the case for grey matter loss as a predictor of disability progression in MS, but it did not look at cognitive function—which can also worsen as MS progresses. DeLuca wasn’t surprised. “Cognitive impairment just doesn’t get the same attention as disability in MS studies,” he said. “But it really should.”
Many patients agree. In a recent survey conducted by the Multiple Sclerosis Association of America and sponsored by Celgene, 27 percent of respondents said maintaining cognitive function was the most important consideration in the management of their MS. Only the prevention of disability progression was reported by more respondents (45 percent).
While cognitive impairment has been recognized in MS for more than a century, a test to measure cognitive function wasn’t developed until 2001. Researchers know that up to 65 percent of people with MS experience some level of cognitive impairment, and the National MS Society recently announced new recommendations for managing cognitive care for people with MS.
So could the same patterns of grey matter loss associated with disability also be related to cognitive impairment? It’s quite possible, according to DeLuca. “Thalamic damage already has an established relationship with cognitive decline,” he pointed out. “And grey matter loss is seen most intensely in the thalamus of patients with MS. So it’s probable.”
The more specific we can be regarding the role of grey matter loss, the better we can care for patients with MS.
Measuring Grey Matter Loss in Practice
So far, doctors don’t routinely use grey matter loss as a predictor of disability or cognitive impairment when caring for patients, but DeLuca believes that maybe they should consider it. “Grey matter loss could be a trigger for clinicians to watch their patients over time and monitor for potentially related problems,” he explained.
Here’s how cognitive impairment impacts multiple sclerosis. pic.twitter.com/Xuyhu9D0Lk
— Celgene Corporation (@Celgene) September 14, 2016
Given current evidence, DeLuca would like to see more trials differentiating grey matter loss from brain volume loss in general. But the main goal, of course, is to identify new ways to look at cognitive impairment. DeLuca is hopeful.
“I think we’ll start to see further research that show the correlation between grey matter and cognitive impairment as well as physical disability,” DeLuca said. “The more specific we can be regarding the role of grey matter loss, the better we can care for patients with MS.”
To learn more about how brain volume loss can affect patients with MS decades later, read “How Multiple Sclerosis Affects the Brain and CNS.”