APOE and Cognitive impairment: The Knight ADRC amyloid PET cohort included 750 individuals with a median age of 71.2 years (interquartile range (IQR) 65.3–76.1 years); 55% were female, 90% self-identified as white, 39% carried at least one apolipoprotein E (APOE) ε4 allele and 16% were cognitively impaired as defined by a Clinical Dementia Rating (CDR) of ≥0.5, which includes mild cognitive impairment (MCI) and AD dementia (Extended Data Table 1).