The study included 147 healthy women, including women of menstruating age and women still using oral contraceptives. The participants underwent examinations during which researchers studied brain function, activity, and response to various events.
Both current and former users of oral contraceptives showed a higher fear reaction in a safe environment compared to women who did not use these drugs.
The effect was most pronounced among women using medications containing a high dose of the hormone ethinyl estradiol.
Neuroimaging studies revealed that the strongest fear responses were accompanied by reduced activity in the hippocampus and medial prefrontal cortex, two brain regions responsible for context recognition and anxiety suppression.
Researchers believe that the hormones in oral contraceptives may disrupt the brain's ability to detect "safety signals" in the surrounding environment, and that the effects of these drugs persist even after they are discontinued. They believe these findings offer explanations for why anxiety and post-traumatic stress disorder are more common in women than in men.
