When people go through very stressful events—like natural disasters, mass shootings, or serious personal trauma—it can leave behind lasting emotional and memory problems.
A new study from researchers at the University of California, Irvine, has found that levels of estrogen in the brain may play a surprising role in how vulnerable someone is to these lasting effects. This could help explain why women are more likely than men to develop post-traumatic stress disorder (PTSD) and face a higher risk of memory issues.
The research team, led by Dr. Tallie Z. Baram, discovered that when people face multiple stressful events at once, they are more likely to experience long-term memory issues. These can include trouble remembering what happened and becoming easily upset by things that remind them of the trauma.
These effects can last for weeks or months. But interestingly, just one stressful event doesn’t seem to cause the same level of harm. It turns out that what’s happening in the brain at the time of the stress.
Estrogen is a hormone often known for its positive effects on memory and learning. But in this study, the scientists found that when estrogen levels in the brain’s memory center—the hippocampus—are high, people (or in this case, female mice) actually become more vulnerable to the negative effects of stress.
Female mice exposed to stress during phases of their hormonal cycle when estrogen was high showed worse memory and more fear when reminded of the trauma.
Interestingly, males were affected too. While men don’t have the same hormonal cycles, their brains also produce estrogen, especially in the hippocampus. These male mice were also affected by stress, but in a milder way and through different types of estrogen receptors in their brain cells.
What’s happening inside the brain is that high estrogen changes how genes work in brain cells. It makes the DNA more “open,” a state called permissive chromatin.
Usually, this helps the brain learn and adapt, but when too much stress hits, this openness can allow damaging changes in the brain’s memory circuits. It’s like the brain is too ready to change, and those changes end up locking in painful memories.
The study also found that different kinds of estrogen receptors are involved in this process. In men, the “alpha” receptor seems to drive the effect, while in women it’s the “beta” receptor.
When researchers blocked these specific receptors, they were able to prevent the long-term memory problems—even though estrogen levels stayed high. This suggests that future treatments could target these receptors in a gender-specific way to reduce the risk of PTSD and other memory issues after trauma.
One key point the study makes is that the timing of stress matters. If someone experiences a traumatic event during a time when their estrogen is already high, their brain may be more sensitive, making the effects of the stress worse and longer lasting.
This could explain why women are more likely to develop PTSD and why their symptoms might be more intense or last longer.
The study also offers new insights into how these brain changes could relate to dementia risk. If stress during high-estrogen periods leads to long-term damage in brain areas responsible for memory, it could increase the chances of memory loss or dementia later in life.
In summary, this research shows that high levels of estrogen, while generally helpful for memory, can actually make the brain more vulnerable during times of intense stress.
This could help explain why women are more affected by PTSD and might also help scientists develop new treatments that are specific to men or women. Understanding how hormones and stress work together in the brain is a big step toward better mental health care.
If you care about brain health, please read studies about inflammation that may actually slow down cognitive decline in older people, and low vitamin D may speed up cognitive decline.
For more health information, please see recent studies about common exercises that could protect against cognitive decline, and results showing that this MIND diet may protect your cognitive function, prevent dementia.
The study is published in Neuron.
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