In our study, the median follow-up time was 13.5 years; however, the accumulation of AD pathology in the brain can occur more than 20 years before clinical symptoms onset.22 Therefore, although we excluded participants with clinically diagnosed dementia at baseline, it is plausible that many remaining individuals are in the prodromal phase of AD, particularly the older individuals and those carrying the APOE ε4 allele, in whom we observed a stronger negative association between snoring and dementia. Here, APOE is linked to Alzheimer disease.