The role of oestrogen in the maturation of the female body alongside reproduction and pregnancy is well known. However, oestrogen has the potential for further physiological effects.
Existing research suggests that women are more prone to developing post-traumatic stress disorder (PTSD) than men, despite the fact that women experience fewer traumatic events than males, on average. A new study indicates that oestrogen may place a crucial role in the development of PTSD. This is a subject I am particularly interested in due to my interest in the military, and a topic I have begun loosely researching for my EPQ.
Different levels of oestrogen have been associated with the brains response to stress, via the hypothalamus, pituitary and adrenal glands. However, a key piece of information from other studies is that women who experience trauma seem to have more trauma related flashback episodes in a particular phase of their menstrual cycle.
This phase occurs around a week after ovulation, where the female body produces more progesterone and less oestrogen. Blood samples from 278 females were examined, and they participated in the Grady Trauma Project.  This is a large scale study that investigates the role of genetic and environmental factors in the development of PTSD among African-American females. 
At childbearing age, women’s levels of oestrogen go up and down depending on where they are in their menstrual cycle, whereas menopausal and postmenopausal women have lower levels of oestrogen.  Those involved in the study then assessed DNA methylation of blood, which is an epigenetic mechanism. It modifies the DNA in a way that suggests that some genes are “turned off.” It was found that a form of oestrogen, serum estradiol, is associated with DNA methylation across the genome.
This is potentially a single gene that is associated with the brain’s fear response, found to be affected by oestrogen levels. Researchers also examined brain functionality using brain imaging techniques.
Research has also been performed with experiments in mice to see if their findings would replicate in rodents. The mice experiments suggest that oestrogen can protect against the formation of PTSD. The authors add that in addition to its role in modulating the fear response, previous studies have also suggested that oestrogen alters pain perception. Scientists have also noted that their findings suggest that oestrogen could be used as a preventive treatment for PTSD. 
While this hypothesis still has a long way to go in terms of the evidence to provide oestrogen as a treatment for PTSD. I thought it was an interesting set of research. While the sample size was small and those who participated had very little variation, alongside the fact that side affects of the treatment have not been considered, I hope that the evidence for the use of oestrogen in the treatment of PTSD prevails.