In this post we’ll look at the impact of trauma on memory and what that means for someone living with PTSD.
This is one of the things that I struggled to convey to people after experiencing my trauma. Each time I complained that I thought my memory wasn’t working the way it should, the way I was used to it being, I was told that inability to concentrate was a common symptom of PTSD. It was explained to me that the brain was attending to too many things in my environment and that it had little resource left to move things from short term to longer term storage. I was reassured that everything would return to normal once I was “healed”.
It was difficult to explain exactly what it was that I was experiencing that felt so disturbing to me. I would say things like, “My timelines seem screwed up in my memory.” and again, I would be met with the “inability to concentrate” excuse which didn’t quite fit what I was sensing, especially since my re-experiencing symptoms had lessened and were far less impactful to my day to day. It wasn’t until I heard it actually explained to me via Bessel Vander Kolk in the Treating Trauma series through NICABM, that any light-bulbs popped on in my head. I spent 8 years looking for this answer that had been out there all along.
Okay, so this may be a little bit difficult to follow but I’m going to try to keep it as clear as I possibly can. To fully understand how trauma impacts our memory we first have to understand that there are two major categories of memory and four subtypes of memory and that because trauma directly affects the brain, it also directly impacts these four types of memory.
The first major category of memory is called Explicit or Declarative memory, it is a conscious memory and involves awareness of facts or events that have happened to a person. It sounds pretty straight forward but this category is further subdivided into two additional types of memory, semantic and episodic.
Semantic memory is the memory of general knowledge and fact; these are memories that help you to identify things in your environment, like to know a bicycle is a bicycle, or know what a television is. It is essentially our general knowledge of the world around us.
Episodic memory is the other sub-type of our declarative memory system, and it is our autobiographical memory of an event or experience – the who, what and where of that event. Take for example, a bad call at work, you will remember who was there, what street you were on and when that particular event happened. This is autobiographical memory at its best.
Before I go into how trauma effects these memory systems I want to go over the second major category of memory, the Implicit or Non-declarative memory system. This system is a subconscious system, that is, it operates below our level of conscious awareness and is made up of our Emotional and Procedural memories.
Emotional memories are just that, they are memories of an emotion that you felt at the time of the experience or event. We can often look at something, an object perhaps or hear a melody and be overwhelmed by intense feelings associated with a past experience or event related to that object or melody, this is how emotional memories are expressed.
Procedural memories are basically our knowledge of how to do things without having to resort to conscious memory. Examples of procedural memory are things like riding a bike, once we’ve learned how to ride the bike, we don’t have to sit and relearn those procedures over and over each time we pick up the bike, we merely employ our procedural memory system and ride away. Things like starting an IV or driving your vehicle all rely upon procedural memory.
Okay, so now we have a basic knowledge of our memory systems and what each of them does for us, so lets look at how trauma impacts each of those types of memory.
So lets go back to our Implicit memory system, specifically our semantic memory (remember, bike, television, car, etc.), these memories are created in the temporal lobe and inferior parietal cortex using information from different areas of the brain. When we experience a trauma this ability to collect and store the information can be disrupted. Sounds, words, images, etc. all arise from different areas of the brain and usually would combine in these brain areas to form a semantic memory, unfortunately, trauma prevents the combination of these incoming information signals and thus a semantic memory of the environment cannot be formed.
Our next Implicit memory system is Episodic memory, and this is the one that was most relevant to my concerns. We form and recall episodic memory in the hippocampus, and we already know that the hippocampus is a major site of dysregulation in terms of PTSD. When we experience trauma, it can shut down our episodic memory system and fragment the sequence of events. The thing with this is it doesn’t only effect the moment of trauma or the trauma memory itself, it has a longer term effect in that it can fragment our sequencing timeline for newer events as well. So when I am asked a question about whether I remember X event, I often respond with confusion because where the person is talking of an event months ago, I am swearing it only happened days or a week ago – my autobiographical memory is fragmented because that memory system is not working properly. (I am not crazy!!!).
Further to this, we can now understand why some people who experience trauma have a relative amnesia to the event or parts of the event/experience. We can now see why, when someone is trying to describe their traumatic experience, they can have difficulty with the sequencing of events within that memory and it is a very distressing and disturbing experience for the sufferer. It also alludes to the experience of actually “being further away” from the traumatic event but not feeling like you are. I am currently 9 years from the traumatic call that ended my career, but in my recall, it seems to sit only within the 2 or 3 year autobiographical timeline. (Our brains are truly fascinating organs.)
Okay, so that was our conscious awareness, now lets see how trauma impacts our Implicit memory system, starting with our Emotional memory.
Emotional memory is regulated by the amygdala – yep, that’s a huge area of concern in terms of PTSD. Now what trauma does, is it causes dysregulation of emotional signalling and so someone whose suffered trauma can experience emotional memories that are out of context to the environment they are in. Highly emotional and painful reactions can seem to appear out of nowhere and have little to no relevance to the environment the person finds themselves in. That is because the majority of emotional memory processing is occurring below the level of conscious awareness, so while the brain may be attending to the processing of the traumatic event, the person is consciously doing something completely innocuous and unrelated to the trauma. You may think you’re doing something to get your mind off the trauma, but your brain is not.
Finally, we have procedural memory. New habits are formed in the striatum of the brain and procedural memories are just that, a type of habit that is so routine it does not require conscious thought to perform. Trauma can change the patterns of procedural memory and not allow those patterns to extinguish. Let’s put it this way, a procedural memory requires learning a coordinated sequence of physical movements to the extent that you don’t require conscious thought to perform the task or movement. When you experience an overwhelming traumatic event, your brain and body remember the pattern of reactions that were activated in response to that threat/trauma, it forms a procedural memory which does not extinguish and prevents us from restoring the body to a calm, peaceful state. Any reminder of a threat/trauma will activate that procedural memory. Ducking or running when you hear a loud noise, or automatically going into a protective stance upon interpretation of the slightest threat are examples of procedural memories acquired at the point of trauma.
It is all well and good to identify where our brains are fouling up and simplistically think that all we need to do is over ride that mistake but for people with trauma, a lot of what they are experiencing is below the level of conscious awareness, they are not in control of what their brain is doing at that level and so these behaviors will surface as if out of nowhere from the perspective of an outsider. Truly they are not out of nowhere, and if we can all understand and accept this as sufferers, it can drastically reduce the experiences of embarrassment or shame we feel when these things happen. It’s not you, it’s how the PTSD affects your brain.
I hope that helps to clear up some issues for those out there who don’t understand why they are reacting the way they are after their trauma. I hope it helps to normalize the things you are experiencing now in your post trauma world.
Always remember, it’s not You, it’s just the PTSD.