245 Sleep and cortical thickness are influenced by surgical menopause

Introduction Early loss of 17β-estradiol (E2), as experienced by women with bilateral salpingo-oophorectomy (BSO; removal of ovaries and fallopian tubes), is associated with increased prevalence of sleep disorders and greater Alzheimer’s disease (AD) risk. In older adults, poor sleep heightens AD risk; hypoxia increases markers for incipient AD, including circulating Aβ, and is linked to prefrontal cortical thinning. Thus, we wondered: 1) if this at-risk population of middle-aged women with BSO had sleep hypoxia, measured by oxygen desaturation, and 2) whether this related to decreased prefrontal cortical thickness in women taking and not taking estradiol therapy (ET). Methods Sleep and percent oxygen desaturation (SPO2%) were measured via at-home polysomnography (TEMEC). Prefrontal cortical thickness was obtained from T1-weighted structural scans using the CIVET pipeline. We recruited middle-age women with BSO, some of whom were taking ET (BSO+ET; n=15), and some not (BSO; n=15). We compared their sleep and cortical thickness with that of age and education-matched premenopausal controls (AMC; n=18). Results Women with BSO (BSO, BSO+ET) had lower minimum SPO2% values than AMC, and thinner right medial orbitofrontal (rmOF) cortices. There was a trend for women with BSO to have lower average SPO2% than AMC. Analyses separating groups based on ET therapy status (BSO vs BSO+ET vs AMC) revealed only trending differences between groups, such that women with BSO tended to have lower minimum SPO2% and thinner rmOF cortices than AMC. Conclusion These preliminary results suggest early loss of E2 due to BSO may drive greater drops in SPO2% in middle-age women, and may be related to reduced prefrontal cortical thickness. This study is the first to show hypoxia in women with BSO. Support (if any) Ontario Graduate Scholarship Award (to LG), Alzheimer’s Association Research Fellowship (co-sponsored by Brain Canada Foundation; AARF-17-504715 to NJG), Alzheimer’s Society Canada Postdoctoral Fellowship (to AA), Canadian Institutes of Health Research (CIHR) Masters Award (to LG, AB, and RR), Wilfred and Joyce Posluns Chair in Women’s Brain Health and Aging (from the Posluns Family Foundation, CIHR, Ontario Brain Institute, and Alzheimer Society of Canada; WJP-150643 to GE)