Assessing brain atrophy rates in a large population of untreated multiple sclerosis subtypes

Objective: To assess the time course of brain atrophy and the difference across clinical subtypes in multiple sclerosis (MS). Methods: The percent brain volume change (PBVC) was computed on existing longitudinal (2 time points) T1-weighted MRI from untreated (trial and nontrial) patients with MS. Patients (n = 963) were classified as clinically isolated syndromes suggestive of MS (CIS, 16%), relapsing-remitting (RR, 60%), secondary progressive (SP, 15%), and primary progressive (9%) MS. The median length of follow-up was 14 months (range 12–68). Results: There was marked heterogeneity of the annualized PBVC (PBVC/y) across MS subtypes ( p = 0.003), with higher PBVC/y in SP than in CIS ( p = 0.003). However, this heterogeneity disappeared when data were corrected for the baseline normalized brain volume. When the MS population was divided into trial and nontrial subjects, the heterogeneity of PBVC/y across MS subtypes was present only in the second group, due to the higher PBVC/y values found in trial data in CIS ( p = 0.01) and RR ( p Conclusions: This first large study in untreated patients with multiple sclerosis (MS) with different disease subtypes shows that brain atrophy proceeds relentlessly throughout the course of MS, with a rate that seems largely independent of the MS subtype, when adjusting for baseline brain volume.