Progressive grey matter atrophy in clinically early relapsing-remitting multiple sclerosis

Brain atrophy appears to occur in patients with multiple sclerosis (MS) in excess of that associated with normal ageing, and may be observed early in the clinical course of the disease. The dynamics and tissue specificity of this process remain unclear. This preliminary study explored the evolution of brain grey matter (GM) and white matter (WM) volume loss (as fractions of total intracranial volumes) in 13 subjects with relapsing-remitting MS (mean disease duration 1.9 years at first scan), compared with nine normal control (NC) subjects. Subjects were scanned every six months for 18 months. In MS compared with NC subjects, significant differences in WM fractional volumes were observed at baseline (mean -5.8%, P = 0.008) but no apparent progressive WM tissue loss was detected. In contrast, while no significant differences in GM fractional volumes were observed at baseline, there was significantly greater time-related volume loss in MS compared with NC subjects over the follow-up period (circa -0.0086 per year in MS subjects, -0.0021 per year in the NC subjects, difference P = 0.010). These results suggest that while both GM and WM atrophy are seen early in the clinical course of MS, they may not occur concurrently and may evolve at different rates.