APOE and Encephalopathy: The ApoE-ε4 allele, particularly ε4/ε4 homozygosity, has been recognized as the sole established risk factor for CAA-ri, as previous studies have indicated a high prevalence of ε4/ε4 (76.9%) among patients with CAA-ri.[9] The prominent clinical features are rapidly progressive cognitive decline, focal neurological deficits, encephalopathy, seizures, and headache.