Patients with relapsing-remitting multiple sclerosis show accelerated whole brain volume and thalamic volume loss early in disease

The aim of this study was to investigate the dynamics of annual whole brain volume loss (BVL/year) and annual thalamic volume loss (ThalaVL/year) in patients with relapsing-remitting multiple sclerosis (PwRRMS) during the course of the disease. A longitudinal database of magnetic resonance imaging (MRI) scans of 195 healthy individuals (age range, 22.8-63.7 years) and longitudinal MRI data of 256 PwRRMS (age range, 20.1-60.8 years) were analyzed and compared. BVL/year and ThalaVL/year were computed for healthy individuals as well as for all patients with MS using a Jacobian integration approach. A linear regression was used to compute the relationship between age and BVL/year and ThalaVL/year for healthy individuals. The linear regression was then used to decompose the BVL/year and ThalaVL/year into a multiple sclerosis (MS)-related and an age-related component for each PwRRMS. PwRRMS were dichotomized into early-phase RRMS (disease duration ≤ 6 years) and later-phase RRMS (disease duration > 6 years), and a t-test was performed to test for differences between these groups. The 135 early-phase patients (disease duration, ≤ 6 years) had statistically significantly higher MS-related BVL/year than the later-phase patients (n = 121) (- 0.21% vs. - 0.06%, p = 0.007). For MS-related ThalaVL/year, the difference between the groups was even more pronounced (- 0.39% vs. - 0.00%, p