Late onset multiple sclerosis is associated with more severe ventricle expansion

Background: Late-onset multiple sclerosis (LOMS) is associated with faster disability progression than persons with adult-onset MS (PwAOMS). The differences in brain atrophy are currently unknown. Objectives: To determine MRI-derived atrophy rates in persons with late-onset MS (PwLOMS) and compare them to an age-matched and disease duration-matched sample of PwAOMS. Methods: 870 persons with MS (290 PwLOMS, 290 age-matched PwAOMS, and 290 disease duration-matched PwAOMS), and 150 healthy controls (HCs), were followed for 5 years and 3 years, respectively. Cross-sectional and longitudinal measures of T2-lesion volume (LV), lateral ventricular volume (LVV) and whole brain volume (WBV) were derived. Expanded Disability Status Scale (EDSS) and Multiple Sclerosis Severity Score (MSSS) were calculated. Both analyses were corrected for false discovery rate. Results: Persons with MS exhibited significantly greater annualized WBV loss (-0.88% vs. -0.38%, p<0.001) and annualized LVV expansion (3.1% vs. 1.7%, p=0.002) when compared to HCs. PwLOMS had significantly higher baseline and follow-up median MSSS when compared to both age-matched and disease duration-matched PwAOMS (p<0.026). PwLOMS showed significantly greater percent LVV change (14.3% vs. 9.3% p=0.001) and greater annualized percent LVV change (4.1% vs. 1.6%, p<0.001) compared to age-matched PwAOMS. Conclusion: PwLOMS had higher MSSS and greater ventricle expansion when compared to PwAOMS.