P3‐326: ESTROGEN RECEPTOR‐ALPHA GENE ( ESR1) POLYMORPHISMS AND COGNITIVE FUNCTIONS IN POSTMENOPAUSAL WOMEN

of the cohort was 856 7.0 years; 79% were women; mean MMSE was 29.06 1.1. The genotype makeup of the group was: e4+ 1⁄4 17 (all e3/e4); e4(e3/e3, (e2/e3) 1⁄4 72. A mean of 321 nights per participant of nighttime activity was used to estimate total sleep time. APOE e4+ carriers’ mean nightly sleep time was 6.8 hours (SD 1.4); APOE e4 carriers’ mean nightly sleep time was 7.4 hours (SD 1.6), p1⁄40.16. APOE e4 carriers had higher night-to-night variability in sleep time over the one-year monitoring period (mean 1⁄4 2.0 hours) compared to thosewithout APOE e4 (mean1⁄4 1.6 hours); (p < 0.01). Self-reported hours of sleep were correlated with the objective sleep times (Spearman correlation 1⁄4 .40; p < 0.001). Conclusions: The APOE e4 genotype is associated with greater nighttime variability in sleep time, but not mean sleep time in cognitively normal older adults. Self-report measures in this cognitively intact group regardless of APOE genotype were moderately correlated with sensor based nightly measurement. Whether night-to-night sleep metric variability is an early indicator of increased risk for MCI and subsequent ADwill require longitudinal follow-up.