APOE and dementia: Furthermore, we found that very short and long sleep duration and prolonged sleep latency were associated with dementia and AD mainly among APOE ε4 allele carriers, which was in line with the potential that extreme sleep duration and carrying APOE ε4 allele may act additively or synergistically to be linked with dementia via common pathways such as Alzheimer pathology and neuroinflammation [60].