When most people hear “Post-Traumatic Stress Disorder” or “PTSD”, an image of a distraught soldier assimilating back to regular life comes to mind whether it is from a television show, a movie, or a family member. PTSD is a highly prevalent disorder in the world population but is highest among veterans. The disorder can come from any traumatic event that threatens a person’s life. This includes victims of abuse and natural disaster survivors to name a few. Those with the disorder experience extremely vivid flashbacks, nightmares, intrusive memories, and repetitive replay of the traumatic memory. These major symptoms show that the heart of PTSD is memories. Not only do memories make up a large part of the disorder, but fear as well. After the traumatic event, a person may overgeneralize fear to harmless stimuli – causing daily distress and constant vigilance.
In the article “Emotional Memory in Post-traumatic Stress Disorder: A Systematic PRISMA Review of Controlled Studies,” authors Durand et al. (2019) characterize PTSD as a disorder of emotional memory. Emotional memory “refers to the attribution of emotional significance to a stimulus or event, promoting memory retention.” (Durand et al., 2019). But, in the case of PTSD, this is a maladaptive process that contributes to fear generalization and flashbacks that are triggered by similarities of the traumatic event seen in their everyday life. When asked to do emotional memory tasks (e.g., react to trauma-related words), those with PTSD had more activity in the left dorsal anterior cingulate cortex (dACC) and the right insula. This neuroimaging suggests that PTSD is reliant on emotional memory as the dACC and insula function in emotion processing. Based on this study, current and effective “PTSD treatment such as EMDR (Eye movement desensitization and reprocessing) therapy, could modify and normalize the impact of emotion in memory.” (Durand et al., 2019)
But what if there could be a new kind of therapy based on memory? Authors Grella et. al (2022) provide insight in their article "Reactivating hippocampal-mediated memories during reconsolidation to disrupt fear." The study used fear conditioning as a model for PTSD fear generalization in mice. After a negative experience (i.e., a shock), a competing positive memory (i.e., running on a wheel) was formed to consolidate with the fear memory to make it less negative. Grella et al. used optogenetic tagging of neurons in the dentate gyrus– a hub for memory engrams– to express the positive memory during the reconsolidation of a fear memory successfully. Both studies solidify how key emotional memory consolidation and storage are in PTSD and that the memories are malleable.
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| Emotional Network in the Brain |
Grella et al. worked with mice and optogenetics, but for humans to get those same results, they just need to think of a positive memory. As Durand et al. said, PTSD memories are fixed and hard to change as they are emotional. Therefore, this type of therapy must be done as soon as possible after the traumatic event. In this proposed “memory therapy”, the client can think about something positive in the context of talking about the traumatic event while receiving transcranial magnetic stimulation (TMS) on the insular cortex, dACC, and other areas related to emotional memory. Since this idea is very new, there are different ways to attempt memory reconsolidation for the PTSD client in therapy. They could think back to a positive memory in the place where the bad thing happened or virtual reality could enhance this process by making the image more vivid. But, ethics must be considered as to how often reliving the trauma is too harmful.
Memory-targeted therapy for PTSD has a lot of ethical and practical considerations. But given how prevalent and debilitating PTSD is, new therapies are worth pursuing in research. The studies by Durand et al. and Grella et al. are relatively new. Thus, the future holds potential for emotional memory work in the therapy room.
Durand, Florence et al. “Emotional Memory in Post-traumatic Stress Disorder: A Systematic PRISMA Review of Controlled Studies.” Frontiers in psychology vol. 10 303. 5 Mar. 2019, https://doi.org/10.3389/fpsyg.2019.00303
Grella, S.L., Fortin, A.H., Ruesch, E. et al. Reactivating hippocampal-mediated memories during reconsolidation to disrupt fear. Nat Commun 13, 4733 (2022). https://doi.org/10.1038/s41467-022-32246-8
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