The impact of sex hormones on neural correlates of sleep-dependent memory

Age and sex are two of three predictors of Alzheimer’s Disease, with women being twice as likely to suffer from the disease than men after the age of 75. One potential sex-specific factor is differences in sex hormones, which has been shown to affect spindle activity. We hypothesized that sleep-dependent memory consolidation may be influenced by sex hormones as their decline may be related to pathological aging. This project investigated the impact of sex hormones on sleep-dependent memory in young and midlife women as one potential mechanism for later cognitive vulnerability in women.

We probed the relation between sex hormone fluctuations and sleep-dependent memory consolidation by testing women four times during their menstrual cycle. With my team, we collected EEG and behavioral data from 112 participants. We used time lag cross-correlation and mixed linear models to analyze the significance and directionality of the sleep-mood relationship, and how the interaction between menstrual cycle status and sleep impacted mood levels. And we found the menstrual cycle was not accompanied by significant fluctuations in objective and perceived measures of sleep or in mood. Moreover, using simultaneous EEG-fMRI, I explored the impact of connectivity between hippocampus and cortex during sleep spindles, and the mediating role of this brain activity on memory consolidation. Our data showed that sleep spindles were associated with improved brain connectivity, but they were not influenced by menstrual cycle.

Related publications:

• Shuster, A. E., Simon, K. C., Zhang, J., Sattari, N., Pena, A., Alzueta, E., de Zambotti, M., Baker, F. C., & Mednick, S. C. (2023). Good Sleep is a Mood Buffer for Young Women During Menses. Sleep, zsad072. https://doi.org/10.1093/sleep/zsad072 • Alzueta, E., Zambotti, M. de, Javitz, H., Dulai, T., Albinni, B., Simon, K. C., Sattari, N., Zhang, J., Shuster, A., Mednick, S. C., & Baker, F. C. (2022). Tracking Sleep, Temperature, Heart Rate, and Daily Symptoms Across the Menstrual Cycle with the Oura Ring in Healthy Women. International Journal of Women’s Health, 14, 491–503. https://doi.org/10.2147/IJWH.S341917