Why Can’t Accident Victims Remember What Happened to Them?

Memory blanks, flashbacks and an eventual distortion of the traumatic event are all normal reactions to experiencing a disaster

Photo: ICMA Photos

What happens when you’ve been through something traumatic, like a car crash or a train derailment? Often, victims don’t even remember what happens. It’s not just because the accident was too horrible to want to remember; however much the victim might want to piece together what happened, his brain wasn’t working on making memories—it was working on survival. Scientific American explains:

The same mechanisms that kept his brain sharp enough to escape immediate danger may also make it harder for both to recall the accident, and to put the trauma behind him. “The normal thing is that the person doesn’t remember the moment of the accident or right after,” says clinical psychologist Javier Rodriguez Escobar of trauma therapy team Grupo Isis in Seville…That’s because the mind and the body enter a more alert but also more stressed state, with trade-offs that can save your life, but harm your mind’s memory-making abilities.

In other words, while caught up in the event itself, your brain strips down to its most basic fight-or-flight response. Oftentimes, this helps the victim think clearly enough to find an escape route—at the cost, though, of processes like memory-making. Adrenaline starts pumping, helping the victim to react quickly and giving him extra strength to escape his predicament. SciAm:

also would have stimulated his vagus nerve, which runs from his spine to his brain. Although adrenaline cannot cross the blood–brain barrier, the vagus can promote noradrenaline production in the brain. That hormone activates the amygdala, which helps form memories.

But as SciAm points out, researchers know that an excessive flood of noradrenaline actually destroys the brain’s ability to store memories. Additionally, adrenaline tends to block out non-pertinent information, helping a person focus on only those things he needs to know in order to survive. For these reasons, trauma victims often do not remember key details they experienced during the disaster.

After the event, the victim may suffer from flashbacks. These, too, are a normal reaction to trauma, SciAm says. Usually, distressing flashbacks of the event fade over time. Pharmaceuticals and targeted therapy can help speed that process along, too. For serious trauma, this process can take weeks or months, on average.

More from Smithsonian.com:

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