Topography and cognitive impact of brain iron deposition in cerebral amyloid angiopathy: Evidence from 7T quantitative susceptibility mapping

INTRODUCTION: While brain iron accumulation has been linked to cognitive impairment in aging and small vessel diseases, its spatial pattern and clinical significance in cerebral amyloid angiopathy (CAA) remain poorly defined. METHODS: Quantitative susceptibility mapping (QSM) was used to assess region-specific iron deposition across cortical, subcortical, and limbic areas. Associations with conventional cerebral small vessel disease (CSVD) markers-white matter hyperintensities (WMHs), perivascular spaces (PVS), cerebral microbleeds (CMBs), and cortical superficial siderosis (cSS)-were analyzed. A composite Iron Deposition Index (IDI) was generated. RESULTS: Cortical iron correlated with WMH burden, while PVS was positively associated with deep gray matter iron but negatively associated with cortical iron deposition. The IDI was independently associated with global cognition and memory. Combined cortical and deep iron burden explained cognitive outcomes better than traditional CSVD markers. DISCUSSION: QSM demonstrates distinct cortical iron accumulation in CAA, providing correlational evidence with potential implications for understanding vascular cognitive impairment.