APOE and early-onset autosomal dominant Alzheimer disease: Exploring genetic markers relating to Alzheimer's disease, there was no association between brain-PAD and APOE ɛ4 carrier status (456 participants; β=0·6 years [95% CI –1·0 to 2·3]) or Alzheimer's disease Polygenic Risk Score (426 participants; β=–0·3 years [–1·0 to 0·5]).