Research master thesis | Psychology (research) (MSc)
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Menstrual cycle-related fluctuations in the hormones estradiol and progesterone affect brain function and structure, leading to changes in behavior and cognition. Low or falling estradiol,...Show moreMenstrual cycle-related fluctuations in the hormones estradiol and progesterone affect brain function and structure, leading to changes in behavior and cognition. Low or falling estradiol, especially with high or increasing progesterone, may impair cognition, while estradiol may enhance it. However, the precise interaction between these hormones and cognitive processes remains unclear, with inconsistent study results. Recent neuroimaging findings suggest using dense-sampling designs to track hormonal and cognitive fluctuations intensively. This study used such a design to examine the effects of progesterone/estradiol on cognitive performance and the theta/beta ratio (TBR), a marker of attentional control. We expected high estradiol to enhance cognitive performance. Additionally, we anticipated that TBR would mediate the relationship between progesterone and cognitive performance, with high progesterone levels leading to decreased TBR, indicating enhanced attentional control. Daily hormone levels and quasi-daily cognitive performance and TBR measures were collected from a healthy, naturally-cycling woman. We used a Flanker task to capture response conflict and an N-Back task with three levels of complexity to capture response sensitivity. For our analyses we used generalized additive models (GAMs). Increased progesterone/estradiol ratio was associated with improved response inhibition accuracy (but not speed) and working memory. Furthermore, decreased progesterone/estradiol ratio was additionally associated with improved working memory. Higher progesterone/estradiol levels were associated with increased N-Back sensitivity, and this was mediated by attentional control. Higher progesterone relative to estradiol also correlated with increased allocation of attentional control resources, suggesting enhanced cognitive processing capacity during high progesterone phases. This aligns with an idea of more flexible cognitive strategies during these phases to compensate for low estradiol. These findings, though needing replication, are the first to combine dense-sampling with electroencephalography, enhancing our understanding of how menstrual cycle hormones impact cognition. This knowledge can inform workplace and educational policies to create more supportive environments for women. Future studies are encouraged to include baseline dopamine levels and time-lagged models.Show less
