LAUSR

Rationale: There are conflicting findings regarding the link between sleep apnea and cognitive dysfunction. Objectives: Investigate associations between indicators of sleep‐disordered breathing (SDB) and cognitive function in the Multi‐Ethnic Study of Atherosclerosis and assess effect modification by the apolipoprotein &egr;‐4 (APOE‐&egr;4) allele. Methods: A diverse population (N = 1,752) underwent type 2 in‐home polysomnography, which included measurement of percentage sleep time less than 90% oxyhemoglobin saturation (%Sat < 90%) and apnea‐hypopnea index (AHI). Epworth Sleepiness Scale score (ESS) and sleep apnea syndrome (SAS; AHI ≥ 5 and ESS > 10) were also analyzed. Cognitive outcomes included the Cognitive Abilities Screening Instrument; Digit Symbol Coding (DSC) test; and Digit Span Tests (DST) Forward and Backward. Results: Participants were 45.4% men, aged 68.1 years (SD, 9.1 yr) with a median AHI of 9.0 and mean ESS of 6.0. Approximately 9.7% had SAS, and 26.8% had at least one copy of the APOE‐&egr;4 allele. In adjusted analyses, a 1‐SD increase in %Sat < 90% and ESS score were associated with a poorer attention and memory assessed by the DST Forward score (&bgr; = ‐0.12 [SE, 0.06] and &bgr; = ‐0.13 [SE, 0.06], respectively; P ≤ 0.05). SAS and higher ESS scores were also associated with poorer attention and processing speed as measured by the DSC (&bgr; = ‐0.69 [SE, 0.35] and &bgr; = ‐1.42 [SE, 0.35], respectively; P < 0.05). The presence of APOE‐&egr;4 allele modified the associations of %Sat < 90% with DST forward and of ESS with DSC (Pinteraction ≤ 0.05). Conclusions: Overnight hypoxemia and sleepiness were associated with cognition. The average effect estimates were small, similar to effect estimates for several other individual dementia risk factors. Associations were strongest in APOE‐&egr;4 risk allele carriers. Our results (1) suggest that SDB be considered among a group of modifiable dementia risk factors, and (2) highlight the potential vulnerability of APOE‐&egr;4 risk allele carriers with SDB.