Sleep apnea and cognition in older APOE4 carriers and non‐carriers

Background Sleep apnea (SA) is common in late life and has received much attention as a possible risk factor for Alzheimer’s disease (AD). However, cross‐sectional findings suggest little, if any, relationship between SA and impaired cognition in Apolipoprotein E ε4 (APOE4) allele carriers and non‐carriers. Preclinical AD detection is essential, and the relationship between SA, APOE4, and cognitive impairment merits further analysis in a large sample. Therefore, we investigated whether SA and APOE4 carrier status were related to neuropsychological functioning using the National Alzheimer’s Coordinating Center (NACC) database. We predicted an interaction between SA and APOE4 carrier status, such that APOE4 carriers with SA would show the most significant impairment in cognition. Method Participants were at least 65 years of age with normal cognitive status. Sample sizes ranged from 1902 to 1945, depending on available neuropsychological data. SA presence or absence was clinician‐determined. Participants completed nine cognitive measures, including semantic memory (verbal category fluency), executive functioning (verbal letter fluency), visual scanning and executive functioning (Trails A and Trails B), global cognitive functioning (total Montreal Cognitive Assessment [MoCA]), and memory (MoCA–delayed recall and Benson Complex Figure Copy – delayed). We compared non‐carriers (ε3/ε3) and heterozygous carriers (ε3/ε4) using three‐way ANOVAs and ANCOVAs, while considering sex and age. Result There were no main or interaction effects of SA, carrier status, or sex on participant age (p>.05). Therefore, age was used as a covariate in three‐way ANCOVAs to enhance the power to detect a significant effect if present. Contrary to our hypotheses, there were no main or interaction effects involving SA (p>.05) with sex or carrier status. An APOE4 main effect was observed only for MoCA total and delayed recall scores. Conclusion Past cross‐sectional studies report a weak or null relationship between SA and cognitive performance. We found no main or interaction effects involving SA with sex or APOE4 carrier status on neuropsychological functioning in a large sample of older adults. Our large sample size helps provide more evidence for these null relationships and is consistent with other large‐sample studies.