Exploring the role of sex, sex steroids, menstrual cycle, and hormonal contraception use in visual working memory: Insights from behavioral and EEG analyses

Sex hormones have been shown to influence cognitive and emotional processes, yet their effects on visual working memory (VWM) are poorly understood. This study aimed to investigate the relationship between VWM, sex, and female hormonal status in participants aged 18-35 years. We recruited 32 males (M) and 133 females, categorized into four groups: naturally cycling females in the early follicular (NCF, n = 33) and mid-luteal (NCL, n = 35) phases of the menstrual cycle, oral contraceptive (OC, n = 37), and intrauterine device users (IUD, n = 28). Participants completed a bilateral change detection task while behavioral and EEG data were recorded. We evaluated VWM performance and associated brain electrophysiological responses, specifically Contralateral Delay Activity (CDA). Salivary levels of testosterone, progesterone, and estradiol were assessed. We found no systematic differences in VWM task performance or CDA between groups, nor any correlations with hormone levels. However, an exception to this was that NCF females performed worse than OC users when recalling four items. Age emerged as a significant covariate, with greater age being linked to poorer performance. An interaction between age and group in memory capacity highlighted differential patterns of age-related cognitive decline across sexes and female hormonal status groups. These findings provide valuable insights into the broader relationship between sex, sex hormones, and cognition. They suggest that in studies employing a between-subject design, hormone-dependent differences in more complex processes, such as visuospatial performance, are unlikely to stem from the role of sex hormones in VWM and may instead arise from other factors.