I was asked to write a little bit about memory and how it works and why some people with PTSD end up with memory problems. What we call neurocognitive stuff isn’t my specialty, but I’ll do my best to explain the issue from a clinician’s perspective.
Memory is made of multiple parts. To form a memory, we must first perceive something. With perception, let’s start with our five senses: Taste, Touch, Smell, Sight, Sound. As some of you know, I like to consider emotions as our sixth sense. These senses give us information about the world.
After we perceive something, to remember it, we must then encode it. In other words we have to decide (consciously or unconsciously) that something is worthy of our attention and actually notice it. Think about meeting someone new and remembering their name. I’m terrible at this because I don’t encode what I hear. Some people have learned that to remember a name, when they hear it, they repeat it, deliberately taking note so that it can be encoded and recalled later.
Once encoded, the memory gets stored. How this works and where in the brain memories get filed away is beyond my area. What I do know is that brain damage can damage memory. This includes actual structural trauma to the brain (traumatic brain injury, concussion, stroke, icepick lobotomy) as well as the degeneration of neurons with aging, drinking too much, poor diet, doing drugs etc… They have found that by learning new skills, new connections between the neurons are built which adds in some redundancy to stave off dementia.
We then must be able to retrieve or recall the memory. This means sorting through what’s in our brains, figuring out the filing system, and pulling it up. Many have noticed that when under stress, memory retrieval can be challenging. I know I’ve been sitting in an interview feeling like a dumb ass literally at a loss for words because stress impedes my ability to recall even very basic information. I would guess everyone has noticed that a certain smells or hearing a song can retrieve memories that are associated with that sense. And certainly, when we are in a depressed mood, it’s easier to recall every awful thing in our lives and much harder to remember good things. The retrieval of memory can be triggered by the 5 and sixth senses as well as intentional effort.
With PTSD, and frankly anxiety and depression, perception, encoding, storage, and retrieval of memories are impacted. Based on our moods we may be more likely to perceive certain things. Someone with PTSD might see threat where no threat exists, someone with depression is likely to see things with a negative bias. The brain tends to recall negative events more easily anyway under the best of circumstances from left over survival needs; kind of like our appendix. The information then gets encoded with that interpretation embedded with it and then the memory is stored in close proximity to other similar memories.
Sometimes people’s brains deliberately (consciously and unconsciously) forget what has been stored in memory because it’s significantly traumatic; but! Even though we block the ability to recall something, the something is still there. When we try not to remember something that we remember, it’s called dissociation. In the past it’s been called the thousand yard stare. Someone is present physically but not mentally because they are deeply engaged in remembering something they don’t want to or effortfully blocking the memory as it tries to come forth. Dissociation can also happen when sometimes tries to split off emotional experience from life: the emotional experiences happen and impact the 4 processes of memory even when someone is engaged in emotional numbing as is common in PTSD.
If someone is in a heightened emotional state (fight flight freeze type stress) when something happens, the ancient monkey, instinctive, highly emotional brain is online and doing the memory work as opposed to our more rational decision making, planning, evolved homosapien brain. This has a significant impact on the accuracy of the memory and our ability to make sense of it. It causes the memory to create an almost instinctual response when it’s recall is triggered. This is also true of memories from early childhood when even small things can seem traumatic.
The rational behind the PTSD treatment EMDR is to use bilateral stimulation to access that old instinctual brain and the new rational brain while recalling a memory that has previously been stored in the old brain to integrate it into the new brain so that the memory is no longer on an emotional instinctive hair trigger. This treatment is now also being used to address relational and attachment issues.
Essentially, at the end of the day, those of us who are in a state of heightened stress or emotional activation will have difficulty with memory and recall accuracy. That’s why when you go to the doctor for a memory check the first thing they ask about is mood. When we address the mood issues through therapy, we increase the ability to recall, but it is still important to fact check what we remember particularly if it was encoded in a heightened mood state.