With respect to APOE ε4 homozygosity, the AD-PRS was significantly higher in individuals with young-onset Alzheimer’s disease (onset before 65 years old) compared to individuals who were cognitively unimpaired and older than 75 years (OR = 8.39 [2.0–35.2], p = 0.003) [28]. Here, APOE is linked to Alzheimer disease.