When American soldiers came home from the Vietnam War, many found it hard to return to normal life. They were haunted by nightmares; unable to shake the images of explosions and death from their minds, even while awake. They struggled with feelings of anxiety, depression, and anger; confused about how to to make sense of what they had witnessed. In 1980, the afflictions of these soldiers — along with research on the psychological impact of trauma on Holocaust survivors, rape victims, and others — led the American Psychiatric Association to define a new condition called Post Traumatic Stress Disorder (PTSD) in the DSM.
Although people often associate PTSD with veterans affected by the horrors of war, the condition can develop in anyone who has experienced a dangerous, shocking, or life-threatening event such as rape, childhood abuse, or a serious accident. According to the National Institute of Mental Health, PTSD will affect 6.8% of U.S. adults in their lifetime. The condition is defined by symptoms like panic attacks, depression, and insomnia, but one of the most characteristic and debilitating symptoms of PTSD is something called “flashbacks.”
Flashbacks are like waking nightmares. They are intense, repeated episodes of re-living the traumatic experience while you’re fully awake. Flashbacks can come on suddenly and feel uncontrollable. They are more like a nightmare than a memory because sufferers often cannot distinguish between the flashback and reality, feeling like the traumatic experience is happening again, in the moment. Flashbacks are vivid, sensory experiences. During one, a sufferer might see, hear, and smell things they saw, heard and smelled during the traumatic moment.
How can flashbacks be such an all consuming, visceral experience? How can they transport you back to the traumatic experience almost instantly? To understand that, we’ll explain what’s happening in your brain when a flashback occurs.
The Impact of Traumatic Events on Memory
To understand what happens in your brain during a flashback, you first need to understand how memories are formed and how trauma disrupts the way this process normally works.
What Happens to Different Parts of the Brain
Memory is a complex process that involves many parts of your brain, but to keep it simple, we’ll focus on two of the key players: the amygdala and the hippocampus. The amygdala is associated with emotional memory — especially the formation of fear-related memories. It evolved to ensure your survival by strongly encoding memories of past dangers you’ve experienced so that you recognize and respond to those threats if you see them again.
The hippocampus, the other region of your brain heavily involved in memory, acts like the brain’s historian. It catalogs all the different details of an experience like who was there, where it happened, and what time of day it was into one cohesive event you can consciously recollect as a memory. In your typical, day-to-day life, your amygdala and hippocampus work together to turn your experiences into distinct long-term memories.
However, during a traumatic event this system works a bit differently. Because you are in danger, your body’s built in fight-or-flight mechanism takes over and your amygdala is overactivated while the hippocampus is suppressed. From an evolutionary perspective, this makes sense: the processes involved in building a cohesive memory are de-prioritized in favor of paying attention to the immediate danger. As a result, your memory becomes jumbled.
After the Threat has Passed
When the threat has passed, you are left with a strong, negative emotional memory of the experience, but you lack clear recollection of the context of the event. In other words, you may learn to associate individual sights, smells, and sounds from the event with danger, but be unable to recall the sequence of events clearly.
Later on, if you encounter things that remind you of the traumatic event, like a smell that was present when it happened, your amygdala will retrieve that memory and respond strongly — signaling that you are in danger and automatically activating your fight-or-flight system. This is why during a flashback, you start sweating, your heart races, and you breath heavily — your amygdala has set off a chain reaction to prepare your body to respond against a threat.
Normally when your amygdala senses a possible threat, your hippocampus will then kick in to bring in context from past memories to determine whether or not you are really in danger. But because the hippocampus wasn’t functioning properly during the traumatic experience, the context of the memory wasn’t stored, and there’s no feedback system to tell your amygdala this situation is different and you’re not in danger. Also, since the memory is retrieved without context like where or when the experience happened, you might even feel like the traumatic experience is happening again.
Therapy Can Help You Overcome Flashbacks
Understanding what’s happening in your brain during a PTSD flashback can help you learn strategies to cope. You can work with a therapist to identify triggers for your flashbacks, such as certain objects, people, or places. Then, you can work with them to identify ways to respond calmly to these triggers through relaxation techniques as well as cognitive and exposure therapies.
While PTSD can be a debilitating condition — in some cases taking years for the survivor to be stable and healthy enough to process the trauma — with appropriate treatment it can be successfully overcome.