memory & PTSD
- A number of changes in memory functioning have been identified in PTSD - bias toward enhanced recall of trauma-related material
- DSM: PTSD characterized both by high-frequency, distressing intrusive memories & by amnesia for the details of the event
- flashbacks
flashbacks
- a notable feature of memory in PTSD - reliving the experience of the trauma
- dominated by sensory detail
- Images & sensation are usually disjointed & fragmentary
- distortion in the sense of time → the traumatic events seem to be happening in the present rather than belonging to the past
- triggered involuntarily
attention & PTSD
- there is an AB operating very early in processing - shown by slowed color naming of subliminal trauma words on Stroop task + speeded RT to trauma words in a dot probe paradigm
- While AB is clearly important in PTSD, research does not provide evidence that the effects are unique to PTSD
dissociation & PTSD
Symptoms most commonly encountered in trauma: emotional numbing, derealization, depersonalization, and ‘out-of-body’ experiences
When symptoms occur in the course of a traumatic experience = peritraumatic dissociation
* Studies have found peritraumatic dissociation shortly after a trauma to be a good predictor of later PTSD
cognitive-affective reactions to PTSD
- DSM-IV: requirement is to experience intense fear, helplessness or horror at the time of the trauma
- Mental defeat = perceived loss of all autonomy, a state of giving up in one’s own mind & all efforts to retain one’s identity as a human being
- Some emotions depend on an element of cognitive appraisal - traumatic events vary in the time that the victim has to appraise what is happening & to generate corresponding emotions
- High levels of anger (specifically anger with other) → predict slower recovery from PTSD
- Feelings of guilt, shame, sadness, betrayal, humiliation & anger frequently accompany PTSD
beliefs & PTSD
- the subjective perception of threat is often a more influential predictor of distress & failure to respond to treatment
- Central idea: traumatic events shatter people’s basic beliefs & assumption
- A general increase in neg beliefs about the self, others & the world found in trauma victims with PTSD
- PTSD is associated with the belief that trauma has brought about a neg & permanent change in the self & the likelihood of achieving life goals
- Neg interpretations of of symptoms → predicted a slower recovery
cognitive coping strategies & PTSD
- Attempts to suppress unwanted thoughts are usually doomed to fail + afterwards, the thoughts return even more strongly
- deliberate avoidance of intrusive thoughts & memories are unhelpful - related to a slower recovery from PTSD
social support & PTSD
- Social support has been shown to have the strongest effect size of risk factors for PTSD
- a neg social env is a better indicator of PTSD symptomatology than lack of pos support
- Neg social support appears to be more prevalent for women + relationship between neg social support & later PTSD symptoms is stronger for women
what is EMDR
Eye movement desensitization and reprocessing (EMDR): an effective treatment for alleviating trauma symptoms & used to treat PTSD
*Involves patient recalling traumatic memories while simultaneously making horizontal eye movements
* Original rational: catalyzing a rebalancing of the NS → leads to a shift of info that is dysfunctionally locked in the NS
* a lot of support for use & effectiveness
a model of EMDR
procedure of the model of EMDR
- Healthy volunteers recall unpleasant memories for a few seconds → rate those memories in terms of vividness & emotionality
- Then recall those memories again for a longer time - during this recall there is either no dual task (recall only) or the participant makes eye movements while recalling the memories (recall + eye)
- There is a break - lasts between minutes to days
- Memory is recalled under the same conditions & is rated again for vividness & emotionality
This model can be used to test hypothesis about EMDR
hypothesis of EMDR
EMDR works by recalling aversive memories & eye movements do not contribute anything
- PTSD patients often afraid of recalling traumatic memories → prolonged exposure to traumatic memories has pos effects = EMDR may be nothing more than an ‘imaginal exposure’ therapy
- If this is correct: both conditions should the same effect
- 16 relevant experiments all found that vividness & emotionality responses decreases with the addition of eye movements
Conclusion: eye movements matter - the effects cannot be explained by exposure alone
HYPOTHESIS NOT SUPPORTED
hypothesis of EMDR
EMDR works by stimulating interhemispheric communication
- Believed that eye movements increase communication between the left & right hemispheres = enhances ability to remember an aversive event while not being neg aroused
- Gunter & Bodner (2008): posited that if eye movements need to be horizontal to decreases vividness of memories = vertical eye movements would have no or less effect
- Vertical movements: vividness & emotionality decreased just as much
Conclusion: contradicts the interhemispheric communication theory
HYPOTHESIS NOT SUPPORTED
hypothesis of EMDR
EMDR works by taxing working memory during recall
- When we simultaneously do 2 tasks that use WM → the tasks compete for the limited capacity
- Recalling an emotional memory & making eye movements both require WM capacity = leaves less capacity for the memory = memory should become less vivid & less emotional
- During recall: memory becomes alterable = events during recall influence how the memory is restored & may be recalled in the future
HYPOTHESIS IS SUPPORTED
EMDR + WM theory implication
not only eye movements, but any taxing task should attenuate the vividness and hence the emotional tone of the memory
pos memories should be just as affected by EMDR as neg memories - just as neg memories become less unpleasant after using recall+eye, pleasant memories should also become less pleasant
If taxing WM during recall leads to changes in the memory, one might think that increasing the taxing load would increase the memory effects
- found that link between taxing WM and the memory-effect has the form of an inverted U
exposure therapy for PTSD
3 types of exposure procesure
- In vivo (real-life) exposure
- Imaginal exposure (revisiting the distressing traumatic memory in imagination)
- Interoceptive exposure
exposure therapy for PTSD
exposure therapy & EPT
- Exposure therapy does not alter the existing pathological structure → forms a competing structure that does not include pathological associations among stimulus, response, & meaning representations
- The pathological & normal structures contain overlapping elements = can be activated by the same stimuli & responses
- When therapy is successful → the new structure is more easily retrieved when shared elements are present
- But when the old, pathological structure is activated = relapse
prolonged exposure therapy for PTSD
2 principal components of PE therapy:
- In vivo exposure to trauma reminders designed to help patients overcome avoidance of safe situations and objects
- Imaginal exposure designed to help patients process & digest the traumatic event
Goal of PE: to promote emotional processing through deliberate, systematic confrontation with trauma-related stimuli
prolonged exposure therapy for PTSD
in vivo exposure
designed to target PTSD patients’ wrongful perceptions about stimuli, thier anxity & themselves
* Exercises involve approaching safe situations that patients perceive to be dangerous + situations that they avoid because the situations are trauma reminders
* designed to achieve the two necessary conditions for emotional processing: activation of the trauma cognitive structure & disconfirmation of the expected disasters
prolonged exposure therapy for PTSD
imaginal exposure
a large part of the PE session - individuals with PTSD frequently hold wrongful belief that recalling the trauma memory is dangerous or harmful + that anxiety will last forever when thinking about the trauma
designed to:
* Help patients organize the memory, reexamine neg perceptions about themselves & others
* Distinguish between thinking about the trauma & reexperiencing the trauma
* Remember the trauma without causing undue anxiety through extinction
* Foster the realization that engaging in the trauma memory does not result in harm
prolonged exposure therapy for PTSD
steps of PE therapy process
- first session: therapist provides a rationale + together with patient determine which trauma to focus on
- second session: discussion of common reactions to trauma + introduction to in vivo exposure (conducted outside sessions)
- third session: therapist presents a rationale for imaginal exposure & conducts it
- remainder: begins with a review of the previous week’s homework followed by imaginal exposure & processing
- final session: therapist & patient review progress, discuss lessons learned & develop a plan for relapse prevention
prolonged exposure therapy for PTSD
effectiveness
- PE has compared favorably to waitlist, supportive counseling & treatment as usual
- PE vs EMDR: both produced significant improvement in PTSD, depression & anxiety, but they did not differ
- PE has been found to be effective with PTSD sufferers across a wide variety of trauma types & it has demonstrated efficacy with PTSD sufferers with a number of common comorbid disorders
brain changes in PTSD
Amygdala and medial prefrontal cortex activation in PTSD
- Present happy and fearful faces to PTSD and healthy controls
- Measured amygdala and mPFC activities to these faces
- PTSD group showed hyperactivation of amygdala and hypoactivation of prefrontal
cortex in response to fearful faces compared to the control group - Disbalance of prefrontal-amygdala system
brain changes in PTSD
abnormal structural changes in the hippocampus
- Reduced hippocampal volume impairs one’s capability to contextualize, leading to maladaptive fear reactions
does PTSD reduce hippocampal volume:
* No differences in hippocampal volume between PTSD and healthy twins
* reduced hippocampal size is a genetically determined trait that pre-dates the exposure to combat (Risk factor!)
* tldr: PTSD doesn’t reduce hippocampal volume
