Paramagnetic Rim Lesions and Choroid Plexus Volume at Diagnosis Are Associated With Cognitive Progression Independent of Relapse and MRI Activity in Early Relapsing–Remitting Multiple Sclerosis

Paramagnetic rim lesions (PRLs) and choroid plexus (CP) enlargement reflect smoldering inflammation in multiple sclerosis. Their role in cognitive progression remains unexplored. Eighty-seven early relapsing-remitting MS patients were enrolled at diagnosis and followed longitudinally. PRLs and CP volume were evaluated at diagnosis using 3 T-MRI. Cognitive decline over time was classified as cognitive progression independent of relapse/MRI activity (PIRMA). Fifty-five patients (63.2%) showed meaningful cognitive decline: 44 (80.0%) were cognitive PIRMA. PRLs and CP volume at diagnosis were associated with cognitive PIRMA. PRLs and larger CP reflect cognitive progression independent of clinical/MRI activity, supporting their role as smoldering disease activity markers.