Striking difference between GM and WM loss in progressive MS

A story recently appeared on MSNews describing the strong relationship between gray matter (GM) atrophy and disability in MS. More evidence for that relationship now comes from a longitudinal MRI study that shows gray matter loss is greatly accelerated in progressive courses of MS while white matter loss stays consistent over time.

In this study, 70 MS subjects (7 CIS, 36 RRMS, and 27 SPMS) and 17 non-MS controls were followed for four years with MRIs and neurological exams. Researchers analyzed the images to calculate the volumes of the GM areas, white matter (WM) areas, and the whole brain. The researchers found that people with MS lost WM volume over time at approximately 3 times the rate of the controls, regardless of their disease stage. However, loss of GM accelerated sharply in SPMS: whereas CIS subjects converting to RRMS lost GM volume at 3.4 times the rate of controls, SPMS subjects lost GM at 14 times the rate of controls. As in the previous study, GM atrophy correlated with disability.

These results help confirm the importance of gray matter loss with respect to progression and disability, and highlight the need to learn what's happening in these areas of the brain so that they can be protected.