Degeneration of the brain’s deep gray matter is associated with more rapid disability in multiple sclerosis patients, a European study shows.
The research, “Deep gray matter volume loss drives disability worsening in multiple sclerosis,” was published in the journal Annals of Neurology.
Scientists know that loss of brain volume is associated with MS disability. The European researchers wanted to see if there was a link between loss of volume in particular parts of the brain and faster disability progression.
The course of MS can differ widely. Some patients experience relapses, then recover — a form of the disease called relapsing-remitting MS. Others develop a progressive disability from the start — a form called primary-progressive MS — or after a period of relapses — a form called secondary-progressive MS.
Nerve cell degeneration plays a vital role in determining whether a patient experiences disability over time. Doctors can assess degeneration with magnetic resonance imaging or measuring brain volume.
Studies have shown that, over time, brain volumes decline more rapidly in MS patients than age-matched healthy people.
The central nervous system has two types of tissue — gray and white matter. Loss of gray matter in the brain is associated with long-term disability.
Scientists know that some gray matter regions lose more volume than others.
The European researchers decided to look for gray matter degeneration patterns associated with faster disability progression in MS patients.
They did a large study of patients at seven European treatment centers. The group included 1,214 people with all types of MS, and healthy controls. The team followed them an average of 2.4 years.
Researchers looked at the volume of all parts of the participants’ brains, including gray matter deep in the subcortex. They used the Expanded Disability Status Scale, or EDSS, to assess disability.
The team discovered that loss of volume in deep subcortex gray matter led to the fastest progression of disability. The finding was true in all forms of MS.
Researchers found the strongest relationship between brain volume deterioration and disability in the thalamus, the largest area of deep gray matter. The thalamus is involved in relaying sensory and movement signals.
The results prompted the team to suggest that regions lying deep in the brain may be more vulnerable to deterioration than other regions.
“We have demonstrated that deep gray matter atrophy is linked to disability progression in multiple sclerosis by using advanced imaging analysis techniques and collecting a large number of MRI scans,” Olga Ciccarelli, the senior author of the study, said in a press release.
“It’s well known that brain atrophy occurs in people with MS and varies by region, but we typically only measure the shrinkage of the whole brain,” said Arman Eshaghi, the study’s lead author. “By looking at brain tissue loss in a more detailed fashion in different MS subtypes, we found it’s possible to predict disability progression in advance. This has many implications in clinical trials that use brain atrophy to investigate the effect of neuroprotective drugs.”
The team emphasized that while assessing deep gray matter deterioration can be a valuable measure in clinical trials, it cannot predict disability progression in individual patients.