The science of the “trauma brain” - WillingToHelpU

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today we have the luck to be able to learn about changes in the brain of trauma survivors from @WillingToHelpU. Please leave your thoughts on the topic and your appreciation for Will under this post.

The science of the “trauma brain” - WillingToHelpU

Disclaimer

After this disclaimer, there will be a summary section about this post. After the summary is a more detailed information section that uses more scientific language.

This post will be discussing neurological aspects of PTSD and dissociation, though research is still being done on these topics. Much of the research on dissociation and DID, especially in recent studies, are done on a sample of white females. This is a large limitation that future research hopes to continually address, but I wanted to make sure this disclaimer was made.

Summary

Our brain is constantly changing as we experience things in life, which includes when someone goes through trauma. When someone experiences trauma, they can have a variety of different responses, partially due to their genetics. This is why, for example, a group of soldiers who go through similar things might not all develop PTSD, some have a genetic ‘key’ that may lead them to developing a disorder. When someone has experienced trauma, many times they will either be hypervigilant, where they are always on the lookout for danger, or dissociative, where they are disconnected from themselves and other things, which can lead to people forgetting things.

Fear Response (Hypervigilance)

This looking out for danger is caused by the fear center of the brain doing too much work. It has been seen in PTSD that the area controlling this fear center does less work when exposed to triggering things, which causes the fear center to go into overdrive. It’s like a see-saw, when the area controlling the fear doesn’t activate, it goes down, which then skyrockets the fear center and produces that anxious feeling.

Forgetting (Dissociative Amnesia)

When people go through something traumatic, it is thought that the memory center of the brain doesn’t process that event fully, which can cause a lot of forgetting. In dissociative disorders such as DID, this is seen outside of trauma, where the brain can forget things more often. This is thought to be due to a specific area in the memory center not doing it’s job. In folks with DID, this area is smaller than in healthy individuals, so it has been highlighted as an area where this problem happens. It is thought that when something is happening, this part of the brain is responsible for taking that event and making it into a memory and that is not happening, which is what results in the forgetting of things. Now that we are able to locate this specific area of the brain for the forgetting, it is possible for us to do scans of the brain to see if someone is experiencing this type of forgetting and it opens the door for people to possibly find a way to help fix it. This research was published in 2023, however, so there is still a long way to go.

Detailed Information

Background

How changes may happen

In the brain, as certain neurological pathways are used, their connections strengthen (often resulting in larger volume). Thanks to neuroplasticity, these connections will continue to change throughout our lives. If a specific area of the brain is not used significantly, it will have a smaller volume, and if an area is hyperactive, it will have a larger volume. This is due to the number of connections an area has, like a tree, with more branches it will take up more space. Same thing in the brain.

Along with these changes, individuals can be predisposed to certain disorders due to genetics. This is part of the Diathesis-Stress Model, where both a genetic factor and a stressor come into play for a disorder. This can be anything from a sex difference (such as females are more prone to developing PTSD) or sizes of different brain areas.

The amygdala

The amygdala is a part of the brain that helps to process emotion and memory. It is also connected to the ‘fight-or-flight’ response that individuals may have.It has been seen that the amygdala has heightened responses in individuals with PTSD (Shin, et al., 2006), which makes sense, as a trait often seen in PTSD and trauma is hypervigilance and an increased startle response.

The hippocampus

The hippocampus is the ‘memory center’ of the brain, where it helps to create new memories. Damage to this area can result in amnesia and it has been seen to have smaller volumes in individuals with DID, though the specific reason why is unknown (Ehling, et al., 2008; Vermetten, et al., 2006).

PTSD and the rACC/mPFC

What is the rACC/mPFC?

The rostral anterior cingulate cortex (rACC) is a part of the medial prefrontal cortex (mPFC), which combines both emotion and cognition in the brain. This part of the brain also controls learning in the amygdala. The rACC has an inverse relationship of activity with the amygdala, where if the rACC is highly activated, the amygdala is not very activated and vice versa.

rACC in PTSD

It has been seen in people with PTSD, compared to people without, that they have lower regional cerebral blood flow (rCBF) in the rACC (Semple, et al., 2000). rCBF measures how much blood is sent to an area, and areas with increased blood flow are having increased activation.

It has also been seen that there is an increase in BOLD signal in the rACC in individuals without PTSD (and no increase in individuals with PTSD) when they are shown words that are combat related (Shin, et al., 2001). BOLD signal is similar to rCBF but also measures oxygen metabolism and blood volume. This means that when exposed to possibly triggering words, people without PTSD had activation in the rACC whereas people with PTSD did not.

What do these two studies mean?

They mean that people with PTSD have a less active rACC when compared to controls. This means that there is no inhibition from the rACC with the amygdala. In people without PTSD, the rACC was activated by triggering words, which would prevent the activation of the amygdala. In the people with PTSD, there is a failure of the rACC to inhibit amygdala activation, which can lead to the symptoms of fear and stress people with PTSD feel.

Dissociative Amnesia and the CA1

What is the CA1

The cornu ammonis is a part of the hippocampus divided into four different sections with different functions. Specifically, section one (CA1) is responsible for memory consolidation, where short-term memory becomes long-term memory.

Damage to the CA1 has shown impairments in autobiographical memory, which has been an area individuals with dissociative amnesia may have significant difficulty in (Bartsch, et al., 2011, 2015). It has also been seen that damage to this area can result in ‘dissociative personality states’ (Forrest, 2001).

Why CA1?

When an individual experiences dissociative amnesia, they are unable to remember specific things, and it is thought that this occurs due to an inability of memory consolidation, where those short-term memories fail to become long-term memories. It was thought that if the problem in dissociative amnesia was exclusively due to the lack of memory consolidation, then there would be a difference in the size of the CA1 in individuals experiencing dissociative amnesia.

What was seen? (Dimitrova, et al., 2023)

In a study looking at dissociation in individuals with DID, they saw smaller volumes in the CA1 with increased levels of dissociative amnesia. They also saw that emotional neglect reduced the volume of several areas of the brain, including the CA1, showing a possible correlation between emotional neglect and dissociation. This study indicates the CA1 as a possible biomarker for dissociative amnesia specifically (though more research needs to be done on this topic).

Conclusion

Amongst other areas of the brain not discussed here, the hippocampus, mPFC, and amygdala are three key areas of the brain related to trauma and dissociation. Further research needs to be done, especially when evaluating the CA1, to see significance across a wider population, but overall, this shows significant areas of the brain that are impacted by trauma and dissociation.

References

Please find all articles referenced here (APA style): https://docs.google.com/document/d/1xFeoQDQo7QTYxLLWUsM5KjXfh2bfeltMZvHtNTjIqs4/edit?usp=sharing