APOE and early-onset autosomal dominant Alzheimer disease: APOE: apolipoprotein E; AD: Alzheimer’s disease; ADAS: Alzheimer’s Disease Assessment Scale; DAD: Disability Assessment for Dementia; iADRS: integrated Alzheimer’s Disease Rating Scale; MCI: mild cognitive impairment; ADCOMS: Alzheimer’s Disease Composite Score; CDR-SB: Clinical Dementia Rating Sum of Boxes.