Study reveals why women more likely to develop PTSD

High brain oestrogen may raise women’s PTSD risk if severe stress strikes during high oestrogen phases, causing memory problems and stronger fear responses, new research has revealed.

The study found that exposure to several simultaneous stressors can lead to persistent memory problems, difficulty recalling events and stronger reactions to trauma reminders.

Tallie Baram is distinguished professor of paediatrics, anatomy and neurobiology, and neurology at UC Irvine’s School of Medicine, and led the research.

Baram said: “High oestrogen is essential for learning, memory and overall brain health.

“But when severe stress hits, the same mechanisms that normally help the brain adapt can backfire, locking in long-lasting memory problems.”

Oestrogen, which usually supports learning and memory, can increase vulnerability when levels are high in the hippocampus, a brain region central to memory formation and retrieval.

Researchers reported that female mice stressed during cycle phases with high oestrogen developed enduring memory loss and heightened fear of reminders, while lower levels were protective. Males, who also have high hippocampal oestrogen, were susceptible more mildly and through different receptor pathways.

High oestrogen loosens the packaging of DNA in brain cells, known as permissive chromatin.

This normally helps learning, but under extreme stress it can allow harmful, lasting changes in memory circuits.

Memory problems were driven by different oestrogen receptors in men and women, alpha in men and beta in women.

Blocking the relevant receptor prevented stress-related memory issues even when oestrogen stayed high. Vulnerability depended on hormone levels at the time of stress, not afterwards.

Co-author Elizabeth Heller is associate professor of pharmacology at the University of Pennsylvania Perelman School of Medicine.

She said: “A lot of what determines vulnerability is the state your brain is already in.

“If a traumatic event hits during a period when oestrogen is already unusually high, the biology can amplify the impact in lasting ways.

“This study shows that a state of high oestrogen in a specific brain region promotes vulnerability to stress in both male and female subjects.”