Most individuals exposed to trauma recover subsequently to their normal levels of response to environmental stimuli. With posttraumatic stress disorder (PTSD), the individuals continue to respond as if by reflex to the cues that remind them of the trauma even though there is no present danger. This is termed extinction failure. Extinction refers to the unlearning of the old learned association between the trauma-related cues and the responses, or to the learning of new inhibitory responses that block the earlier learned response.
Symptoms of PTSD
PTSD comprises both symptoms related to the trauma specifically, such as avoidance of cues that remind the individual of trauma, or arousal with physical or emotional symptoms when faced with a trauma-related cue, and those that represent general distress and dysphoria such as disruption of sleep, irritability, loss of interest, and low mood. All too vivid memories, intrusive thoughts, flashbacks or nightmares, emotional numbness and avoidance are all part of PTSD symptoms.
PTSD affects women twice as often as men after a traumatic event, even though men are more likely to face trauma. In addition, women are likely to have symptoms persisting much longer, on average four times as long, as men, with greater resulting inability to carry on with daily activities. They are more likely also to require more support and urgent care, with higher consumption of health services.
Sex differences in PTSD
This is partly explained in lower animals by the involvement of the sex hormones produced in the male and female reproductive glands in fear learning processes. These observations have led some scientists to postulate that deficits in fear learning cause a higher risk of PTSD symptoms in individuals who have lower levels of the female sex hormones, estradiol and progesterone.
In rats, estrogen administration increases fear conditioning but also promotes extinction and extinction recall. The latter occurs especially well with high levels of estradiol and progesterone, probably because estradiol promotes synaptic potentiation in the region of the brain that inhibits fear responses.
In fact, estradiol may increase the strength of learning in general, thus accounting for the learning of these two contradictory types of response. It may influence multiple systems such as the response of the hypothalamus–pituitary–adrenal (HPA) axis, and the inhibitory gamma-aminobutyric acid (GABA)-ergic, and excitatory noradrenergic systems to stressors.
Other theories put forward to explain this disparity include the fact that assaults are more likely to lead to PTSD and dissociation responses; the difference in the type of violence that men and women are more likely to experience; and the sex-based differences in the perception or experience of trauma.
Menstrual cycles and PTSD symptoms
In support of the sex hormonal theory, it has been observed that anxiety disorders emerge around the age of puberty when women begin to have their monthly cycles, with widely fluctuating hormonal levels across the menstrual phases. During the menstrual cycle, estradiol peaks in the second half of the follicular phase of the cycle and then rises again during the mid-luteal phase, at which time progesterone reaches its peak.
Some scientists showed that PTSD symptoms are more likely to worsen in the mid-luteal phase when the trauma occurred or when the woman was assessed. The postpartum and perimenopausal periods are also known for their high risk of anxiety disorders. All three phases are marked by lower levels of female sex hormones.
In human studies, there has been limited examination of the role of sex differences in this type of learning, which is important in PTSD. One experiment showed that individuals with PTSD had more symptoms related to phobic anxiety during the early follicular phase and late luteal phase, indicating that depression and anxiety were more likely during these phases.
Phobic anxiety symptoms such as feeling afraid in open spaces or on the streets, or avoiding some activities or places out of fear, were thus higher in these specific phases, but in women with PTSD vs those without this condition, phobic symptoms were higher in the early follicular phase than in the mid-luteal phase. This fluctuation was not observed in the non-PTSD group.
It may be that periods of low or falling estradiol and progesterone make women with PTSD more vulnerable to symptoms related to fear or avoidance of trigger factors, for instance. The differences between the timing of exacerbations could be due to the differences in the methods used for different studies. On the other hand, it is still possible that women with PTSD suffer from these symptoms across the cycle, even when estradiol levels are high.
Again, certain phases of the cycle may produce effects that vary by type of trauma. With acute trauma, the impact at different cycle times may differ from that of chronic PTSD. One example is the embedding of trauma-related memories in the mid-luteal phase and hence the development of a pathological trauma response to acute trauma.
As mentioned earlier, the extinction deficits and fear symptoms that occur during the early follicular and late luteal phases may keep PTSD going once it is established. “Our results suggest that lower estradiol might render women more prone to negative affective states [moods] and thus negative thoughts or feelings about past events, including past trauma,” say Rieder and colleagues.
Further research is urgently needed to understand how changes in the hormone levels and their metabolites contribute towards PTSD symptoms in women over the menstrual cycle, especially as other factors are likely to interact with the hormonal fluctuations, including psychological, biological and sociocultural factors.
The cycling of symptoms, if validated by further studies, could pose diagnostic challenges for doctors, emphasizing the need for a better understanding of the dynamics of hormone changes in relation to PTSD symptomatology. Interviews could be timed accordingly to enhance the sensitivity of detection.
Such investigations could also help such women deal with their traumatic experiences by providing a biological explanation.