Therefore, we undertook a comprehensive search of PubMed and Google Scholar between January 1st, 2020 and January 1st, 2025 to identify studies examining key risk factors for Alzheimer’s disease —including risk scores, apolipoprotein E (APOE), immune/inflammatory biomarkers, and amyloid, tau, and neurodegenerative biomarkers—prior to middle age, with no limitations on publication dates. Here, APOE is linked to early-onset autosomal dominant Alzheimer disease.