Dense-Sampling the Menstrual Cycle Using EEG in a Single Case Study: Relating Markers of Cognitive Control and Mental Health

Please refer to the most recent version of this document (09-09-2026).Introduction. Women may show menstrual cycle-related susceptibility to depressive and anxiety symptoms during estradiol (E2) and progesterone (P4) fluctuations. Electrophysiological (EEG) markers, including the error-related negativity (ERN) and resting-state theta/beta ratio (TBR) index cognitive control processes and are emerging biomarkers of adverse mental health outcomes. Methods. Using a proof-of-principle, hypothesis-generating approach, we intensively tracked one healthy, naturally cycling woman in her late twenties for 30 days. We collected daily salivary E2 and P4, mental health data, and EEG. We provide a descriptive case study to showcase a dense-sampling and dynamic time warping (DTW) combination. Results. EEG markers varied considerably across the menstrual cycle. The ERN was larger around ovulation, coinciding with an E2 peak. Around midluteal phase the ERN was smaller, coinciding with a P4 peak. TBR varied most during the early-follicular phase. The DTW networks suggested the ERN was related to TBR, that TBR was related to positive and negative affect, and to response bias on a Go/No-Go task. Discussion. Our descriptive, hypothesis-generating results suggest that cognitive control markers can vary across a menstrual cycle, and that they can be important targets for further study regarding women’s mental health and precision medicine. Cognitive control markers exhibited considerable daily variability, underscoring the importance of accounting for such fluctuations in research.