Studies on Alzheimer's disease have found that the APOE ε4 allele contributes to decreased BBB clearance, resulting in the accumulation of brain iron and β‐amyloid (Aβ) [32, 33], and iron deposition can further impact cognitive function through oxidative stress and neurotoxicity, thereby exacerbating disease progression [34]. This evidence concerns the gene APOE and early-onset autosomal dominant Alzheimer disease.