Up to 70% of Americans experience trauma at some point in their lives, according to the Post-traumatic Stress Disorder Alliance. And its long-term effects may be influenced by any number of factors.
Some of us may never get over the moment of pain — whether mental or physical — forever etched in our memories. Others may be more able to shrug it off, to flip over that memory like a playing card in the brain, its face forever hidden.
There are, of course, middle grounds and other outcomes. To learn more about why we respond to trauma the way we do, we turned to Jennifer Stevens, PhD, assistant professor in the Department of Psychology and Behavioral Sciences at Emory University in Atlanta. She is a memory and trauma expert.
WebMD: What happens in the brain when someone experiences trauma?
Stevens: There is sort of a systemic physiological response that we casually refer to as the fight-or-flight response. This involves the brain detecting a danger in the environment, which is mediated by the amygdala brain region that is important for recognizing threats.
When the fight or flight response is activated, this causes the release of hormones like norepinephrine, which have an effect on different parts of the body. It frees up energy resources and affects memory consolidation processes.
WebMD: Memory consolidation process. That’s interesting. How does that work?
Stevens: During an experience, memory traces are being laid down. Hormones like norepinephrine can promote plasticity — that just means making changes to how two neurons are wired together, which forms the physiological basis of the memory.
WebMD: Does that last a long time? Meaning does the impact of trauma last forever?
Stevens: We know some memories can last a lifetime. Studies, for example, of Holocaust survivors, show that experiencing an event, a highly traumatic event like that, influences the physiology of the brain and the body in terms of medical disorders that are related to stress. And those effects can even be passed down to the next generation.
WebMD: Is this where the phrase “seared in your brain” comes from?
WebMD: Is it possible that some people have that seared-in-your-brain response and some experience a sort of blocking of those traumatic memories? Can they both be true?
Stevens: Many times when people experience a trauma, there are parts of the memory they can’t access or won’t access, and a lot of times in psychology we chalk that up to avoidance. The brain is unwilling to access the parts of the memory where the worst emotions, or the most traumatizing events are. And so both avoidance and the possible loss of memory are part of the diagnostic process. Those are fairly common responses to trauma.
WebMD: Is there a reason one would experience it one way or another?
Stevens: There are definitely risk factors for responding in a particular way when someone experiences a trauma.
We know that more than 60% of Americans will experience a trauma in their lifetime, but not everyone will result with PTSD or depression. Six to 10 percent will have something like post-traumatic stress disorder. Which means there’s something happening prior to the trauma that puts certain people at risk. From huge batches of scientific research we know there are physiological reasons. (People who experience trauma as a child) are at much higher risk of then having PTSD or depression an adult if they experience trauma.
One thing I really wanted to point out is that women are at much higher risk for both post-traumatic stress disorder and depression from experiencing a trauma. There’s a much higher inherited factor for women.
WebMD: What could be an explanation for that?
Stevens: The field of understanding risk factors or psychiatric factors after trauma, it’s really exploding right now. We’re finding that we have to have huge sample sizes to be able to do this sort of research, on the order of tens of thousands of people. The genes we know are going to be reliably related to PTSD and depression are only beginning to emerge.
What they are and whether they influence, like, the release of cortisol and the fight or flight response, we’re probably going to find in the next year.