Understanding sex differences in extinction retention: Pre-extinction stress and sex hormone status.

Difficulties in fear regulation can sometimes result in maladaptive fear responses. To better understand how to improve fear regulation, it is important to determine how known factors, such as sex hormone status and stress, might interact to influence fear memory. Research has shown that women with high estradiol levels (mid-cycle) and men exhibit better extinction retention compared to women with low estradiol levels (women in the early follicular cycle or using oral contraceptives). Stress has also been demonstrated to affect both the learning and retention of extinction. Despite documented interactions between stress and sex hormones, their combined effects have not been thoroughly studied. This study aims to examine the impact of stress as a function of sex hormone status on extinction learning and retention. A total of 168 non-clinical participants were studied, including men (n = 46), women using oral contraceptives (n = 38), women in the early follicular phase (n = 40), and women in mid-cycle (n = 44). On Day 1, fear acquisition training was performed. On day 2, prior to extinction training, half of the participants were exposed to a psychosocial stressor, while the other half performed a non-stressful control task. On day 3, extinction retention was tested. Fear was quantified using skin conductance responses, while stress hormones were quantified through saliva samples. Exposure to stress prior to extinction training did not affect extinction learning, regardless of sex hormone status. In contrast, pre-extinction stress exposure had different effects on extinction retention depending on hormone status. Stressed men showed impairment in extinction retention compared to controls, while the experimental condition had no effect on naturally cycling women. Regardless of stress exposure, early follicular women exhibited a deficit in fear regulation, while mid-cycle women showed effective fear regulation. Among women using oral contraceptives, the stress group demonstrated better extinction retention compared to the control group. These results demonstrate the importance of considering sex hormone status and stress exposure during extinction learning, as both components may modulate extinction retention. These results could help identifying hormonal conditions that may enhance the effectiveness of extinction-based psychological therapies used in the treatment of fear-related disorders.