APOE and Alzheimer disease: ARIA-E (ARIA with edema) and ARIA-H (ARIA with hemosiderin deposition: microhemorrhage and superficial siderosis) both appear to relate to the presence of cerebral amyloid angiopathy (CAA) and ApoE e4, can occur spontaneously in AD, and occur at increased rates relative to the background rates in the setting of amyloid-modifying therapeutic approaches [18].