Sleep and hippocampal function during an associative memory task are influenced by surgical menopause at midlife

Abstract

Background 17β‐estradiol loss is related to Alzheimer’s disease (AD) risk factors, including disordered sleep and associative memory decrements (Gervais et al., 2017; Rentz et al., 2017). Women have higher risk for AD than men, and those with mid‐life 17β‐estradiol loss due to surgical menopause, including bilateral salpingo‐oophorectomy (BSO) before age 48, have even higher risk (Rocca et al., 2007). Our learning objective was to investigate whether sleep and associative memory in women with BSO (mean age 44‐46) would be comparable to those with spontaneous/natural menopause (SM; mean age 57), and whether 17β‐estradiol‐based hormone therapy (ET) might mitigate these effects. Method We assessed sleep using the average of three nights of portable polysomnography (Temec) in women with BSO either taking ET (BSO+ET; n=16), or not (BSO; n=18), and in older spontaneously menopausal women (SM; n=14). Using EEG (Fp1‐Fp2), we obtained sleep staging automatically (Neurobit Technologies). Participants also completed a face‐name associative memory task during functional magnetic resonance imaging. Recognition accuracy and brain activation during encoding were measured. Result BSO exhibited reduced sleep efficiency compared to BSO+ET. For BSO, there was no relationship between percent of total sleep time in N3 and hippocampal activation during associative encoding, even though percent of total sleep time in N3 was negatively associated with hippocampal activation during associative encoding in BSO+ET. For all groups, including BSO, lower latency to consolidated N3 correlated with better associative memory accuracy. There were no group differences in associative memory accuracy. In contrast to BSO, SM showed significantly longer latency to consolidated N3 than BSO+ET. Conclusion Younger women with BSO have comparable sleep to older women in SM. In younger women with BSO, ET improves sleep efficiency. Further, while associative memory may be disrupted by increased latency to consolidated N3 in all women, BSO and BSO+ET showed similar associative memory accuracy and latency to consolidated N3. Only BSO+ET exhibited a significant correlation between hippocampal activity during associative encoding and time spent in N3, indicating that ET may support the negative relationship between N3 and hippocampal function. Overall, ET in younger women with BSO potentially ameliorates poor sleep and associative memory decrements.

Cardiometabolic health across menopausal years is linked to white matter hyperintensities up to a decade later

“…Participants with missing values ('Not a Number (NaN)', 'prefer not to answer ', 'do not know '), were excluded (missing datapoints = 520 for demographic factors, 2,974 for WMH volume, 8,448 for cardiometabolic risk factors, 4,562 for menopausal status, and 101 for hysterectomy/bilateral oophorectomy, with 10% of all participants having missing values for more than 2 variables). 1,015 participants who had undergone a hysterectomy and/or bilateral oophorectomy were excluded in order to focus the study on variation in natural menopause, as surgical menopause may involve independent risks for cardiometabolic diseases (Karia et al, 2021;Pu et al, 2017), as well as brain ageing and dementia (Brown et al, 2023;Gravelsins et al, 2023;Zeydan et al, 2019). 17 participants were excluded due to implausible menopause status data or age at menopause outliers (see section 2.2 for details).…”