Iron accumulation in multiple sclerosis and implications for cognitive and clinical progression: a systematic review of advanced neuroimaging studies

BACKGROUND AND AIMS: Iron-related alterations are frequently implicated in multiple sclerosis (MS) neurodegeneration, but its relationship with clinical symptoms and cognitive impairment remains unclear. We systematically reviewed evidence linking iron-sensitive susceptibility-based magnetic resonance imaging (MRI) metrics to cognitive outcomes, in order to evaluate their potential role as diagnostic and prognostic biomarkers of cognitive decline in MS. MATERIALS AND METHODS: A systematic review was conducted using the PRISMA guidelines. 600 studies were identified by searching PubMed, Scopus, Web of Science, and Embase in October 2025. After screening, 12 studies fulfilled the eligibility criteria and were included. RESULTS: Two main patterns emerged: (i) higher basal ganglia susceptibility/iron-related metrics are consistently linked to worse cognitive performance, particularly information processing speed and executive control; and (ii) thalamic findings are more variable in direction and clinical meaning, with susceptibility often capturing a mixed signal that overlaps with thalamic atrophy. CONCLUSIONS: Iron-sensitive quantitative MRI captures clinically relevant deep gray matter (DGM) pathology associated with cognitive impairment in MS, with basal ganglia measures showing the strongest linkage with cognitive and clinical outcomes. Future studies should include harmonized methodology and a longitudinal component.