5 PTSD and EMDR Flashcards
How does EMDR work?
• Effective treatment for alleviating trauma symptoms , and the positive effects of this treatment have been scientifically confirmed under well-controlled condition
- Providing an opportunity to explore how EMDR works
• The present paper reports on how findings of a long series of experiments that disprove the hypothesis that eye movements or other dual tasks are unnecessary
• These experiments also disproved the idea that ‘bilateral stimulation’ is needed
- moving the eyes up and down produces the same effect as horizontal eye movement, and so do tasks that require no eye movement at all.
• However, it is important that the dual task taxes working memory.
• Several predictions can be derived from the working memory explanation for eye movements in EMDR.
• These seem to hold up extremely well in critical experimental tests, and create a solid explanation on how eye movements work.
• This paper discusses the implications that this theory and the empirical findings may have for the EMDR technique.
History and Effects of EMDR
• Used to treat PTSD
• Recall trauma whilst making horizontal eye movements
- Or bilateral beeps
• The founder of the intervention writes about catalysing a rebalancing of the nervous system, and this leading to a shifting of information that is dysfunctionally locked in the nervous system
• Scepticism from scientific community
• The treatment has met the strict criteria for ‘evidence-based practice’ set by the National Institute for Clinical Excellence
- but it fell short of meeting the Institute of Medicine’s even stricter criteria for efficacy for treating PTSD
• A 2007 article in the British Journal of Psychiatry reconfirmed the conclusion and further stated that was no evidence of a difference in efficacy between EMDR and cognitive behavioural therapy
• Importantly, a recent meta-analysis suggests that Eye Movements are more than clinical folklore, but add to the beneficial effects of EMDR
How to proceed now?
• One option would to leave it at this, accredit EMDR courses, train therapists, and start working with EMDR
• How does it work though?
- As long as that remains unclear, so does patient selection: why is EMDR applied to PTSD, and should it be used to treat all patients with PTSD? How about other Axis I disorders, and, if so, which ones?
- Eg the beeps have never been studied -Since this release (2009) a study was in fact released studying effects of beeps EMDR: Eye movements superior to beeps in taxing working memory and reducing vividness of recollections
van den Hout, M.A., et al. (2011). Behaviour Research and Therapy, 49, 92-98.
• How do you get a solid explanation for how EMDR works?
- Given the confidence with which views supported exclusively by clinical experience are presented, there seem to be quite a few practitioners who believe that gaining clinical experience with EMDR is an ‘effective enough’ strategy.
• But people are bad at intuitive statistics and tend to show confirmation bias: information that agrees with their hypothesis is given more weight than information that disagrees.
• EMDR can be studied using a laboratory model
- Using this model, researchers have tested and discarded a few hypotheses about the effectiveness of EMDR.
A Model of EDMR
• Simple
• First, healthy volunteers recall unpleasant memories for a few seconds.
- They rate those memories in terms of vividness and emotionality
• They then recall those memories for a second, longer time (e.g., several periods of about 24 s)
- During this second recall, there is either no dual task (‘recall only’) or the participant makes eye movements while recalling the memories (‘recall + eye movements’), by visually tracking a white circle that moves from side to side on a computer screen.
• After a break, lasting from between a few minutes to a few days, the memory is recalled under the same conditions as the first time and is rated again in terms of vividness and emotionality.
• This model can be used to test hypotheses about EMDR, such as the following…
Hypothesis 1
EMDR Works by Recalling Aversive Memories and Eye Movements Do Not Contribute Anything
• PTSD is an anxiety disorder, and patients are often afraid of recalling memories of the traumatic event.
• Prolonged exposure to traumatic memories has positive effects and so EMDR may be nothing more than an ‘imaginal exposure’ therapy.
- Eye movements may be unnecessary
• If this is correct, then ‘recall only’ should have the same effect as ‘recall + eye movements’.
- If eye movements do matter, then vividness and/or emotionality should decrease more after ‘recall + eye movements’.
• There are at least 16 relevant experiments that measure vividness and emotionality
- In all of these experiments, vividness and emotional responses decreased with the addition of eye movements to recall, usually for both measures and sometimes just for one
• The pattern of results is unusually robust for this field of study.
• In a meta-analysis from clinical studies (outside the lab), Davidson and Parker (2001) reported that there was no convincing evidence for the efficacy of eye movements.
- Lee and Cuijpers (2012) noted that Davidson and Parker treated all studies as if they were of equal weight, but that the usual practice in meta-analysis is to weigh each study in relation to the number of participants and to calculate the degrees of freedom using the total number of participants, which yields a more appropriate test of significance and provides more power to investigate small magnitude effect sizes.
• An improved meta-analysis by Lee and Cuijpers (2012) involved 14 studies (15 comparisons) that compared eye movements versus no eye movement in full EMDR treatments
- In seven of the studies, all or most participants met criteria for a clinical diagnosis
- This meta-analysis suggests that eye movements have an additive effect (Lee & Cuijpers, 2012).
• The conclusions are clear: eye movements matter, the effects cannot be explained by exposure alone, and this hypothesis can be dismissed.
Hypothesis 2
EMDR Works by Stimulating “Interhemispheric Communication”
• Widely accepted
- many people have come to believe that eye movements increase communication between the left and right brain hemispheres, thereby enhancing the ability to remember an aversive event while not being negatively aroused
- it does not matter which sensory channels are used to stimulate “interhemispheric communication” as long as the stimulus is alternating and rhythmically left-right: beeps that are presented left and then right, left and right tactile stimulation, left and right taps on the table, etc.
• Gunter and Bodner They posited that if eye movements need to be horizontal to decrease the vividness of memories, then vertical eye movements would have no or less effect.
- Participants were asked to recall unpleasant memories under three conditions: eyes fixated, horizontal movements, or vertical movements
- ‘Recall only’ had no effect
- When the white circle moved back and forth horizontally (one movement per s) and was visually tracked, the familiar pattern occurred: vividness and emotionality decreased.
- When the circle moved up and down, vividness and emotionality decreased just as much.
- This is at odds with the ‘interhemispheric communication’ theory
• A counterargument may be that – because an eye projects ipsi-laterally and contra-laterally on the visual cortex– vertical eye movements may also strengthen the interhemispheric communication.
- There is some logic to this, but not much: interhemispheric communication is stimulated more by horizontal eye movement than by vertical eye movement.
Hypothesis 3
EMDR Works by Taxing Working Memory During Recall
• Stored information that is currently active and is used to perform cognitive operations is located in working memory (WM)
- Capacity limited
• Long-term memory, on the other hand, contains memories and knowledge that is not currently active.
- Capacity extremely large
• When we simultaneously do two tasks that each tax WM, the tasks compete for this limited capacity.
• Recalling an emotional memory and making eye movements both require WM capacity, so moving your eyes from side to side while recalling a memory leaves less capacity for the memory
- Should become less vivid and emotional
• This is not unique to traumatic memories; it should also apply for mildly negative memories.
• The next step is important.
- During recall, a memory becomes ‘labile’, meaning that events during recall influence how the memory is restored (or “reconsolidated” as in current parlance) and may be recalled in the future.
- Imagination Inflation effect: When a person tries to form a vivid and detailed image during recall, this influences the original memory, which becomes more vivid and realistic- notorious in police interrogation
- From a WM standpoint, the ‘recall + eye movements’ combination will lead to ‘imagination deflation’. And this should also be evident when the memory is recalled after the dual-task session.
• According to this theory, it makes no difference whether eye movements are horizontal or vertical.
- The effects of vertical eye movements do not agree with an ‘interhemispheric communication theory’, but they do agree with a WM theory.
Other tasks
• A fresh next implication of the WM theory is that not only eye movements, but any taxing task should attenuate the vividness and hence the emotional tone of the memory.
- This has been found.
• While recalling negative memories, participants were asked to perform another task or, as a control condition, performed no dual task.
• These tasks included
1. Auditory shadowing
2. Copying a complex figure
3. Playing a computer game
4. Mental arithmetic
5. Calculating out loud
6. Mindful breathing
• Compared to the ‘recall only’, memories became less vivid and/or less emotional during all these tasks.
Positive Memories
• For obvious reasons, EMDR practitioners are more interested in decreasing unpleasantness of negative autobiographical details than in weakening joyful memories.
• But according to the WM theory, all emotional memories should lose their vividness when WM is taxed during recall.
• A standard part of the EMDR protocol is installing ‘positive cognitions’ by asking the patient to activate a positive cognition, seemingly in an attempt to strengthen this memory trace.
• Curiously, patients are also asked to move the eyes from side to side during the ‘installation of positive cognitions’.
- This seems impractical, because the theory suggests that eye movements do not sharpen, but rather weaken the image.
• Using the very EMDR technique, Hornsveld et al. (2011) tested the effects of (1) recall only, (2) recall + horizontal eye movements and (3) recall+ vertical eye movements on positive memories.
- Consistent with WM theory, findings showed that making eye movements during activation of positive thoughts rendered these thoughts less vivid and less positive, irrespective whether the movements were horizontal or vertical.
• This part of the EMDR protocol is not only ineffective: it is counter-effective, and results in effects that are opposite to the desired ones.
Prospective Memory and Flash-Forwards
- EMDR started out as a trauma therapy, but therapists have begun using it to treat a wide range of disorders
- Many patients with, for instance, anxiety disorders, eating disorders, hypochondriasis, or depression are not (only) tormented by images and thoughts of past aversive events (stored in ‘retrospective’ memory), but also by disturbing images and thoughts about possible future events.
- Such future-oriented images and thoughts are located in ‘prospective’ memory.
- The WM theory says that flash-forwards can be stripped of their impact in the same way as flashbacks.
- The application of EMDR to other disorders than PTSD is mainly anecdotal.
- The WM theory and flashforwards research seem to provide a rational basis for applying the intervention.
How Do We Know If And How Much WM Is Taxed?
• A traditional method for determining whether and how much cognitive capacity a mental task requires was developed by F.C. Donders: the reaction time (RT) task.
• The reasoning is simple and effective:
- task A is administered, where the participant responds as quickly as possible to a probe, and the RT is measured.
- Next, task B is added to A.
- The degree to which the RT to task A slows down produces a quantitative index of the amount of cognitive capacity required by B: the more slowing down, the more capacity B requires.
• When participants were asked to respond to high versus low tones by saying ‘high’ or ‘low’, the RT of the discrimination task was about 600 ms.
• But when people simultaneously made EMDR-like eye movements, the RT increased to about 700 ms, which is a significant difference
Low Working Memory Capacity? Benefit From EMDR
- There are individual differences in working memory capacity in general.
- For individuals who have a stronger delay during an RT task when they make eye movements, eye movements evidently have a large impact.
- The WM theory suggests that, precisely because of this big impact, people with low working memory capacity should benefit a lot from making eye movements
- Five studies were conducted to examine whether working memory capacity predicts how much memory vividness and emotionality decreases as a result of eye movements and other dual tasks during recall.
- Gunter and Bodner (2008) found a significant correlation between working memory capacity and the reduction in vividness and emotionality of memories as a result of ‘recall + eye movements’
- The correlations are negative: individuals who are more distracted by eye movements or other dual tasks (as evidenced from a large delay during a RT task) benefit more greatly from EMDR-type procedures.
Inverted U
• If taxing WM during recall leads to changes in the memory, one might think that increasing the taxing load would increase the memory effects.
- This is a misconception
• The WM theory states that the competition between recall and the distracting task leads to a decrease in vividness and emotionality.
- For this to happen, there needs to be a minimum degree of taxing, but if this taxing exceeds a certain level there will be too little room for recall
- This would, in turn, mean that the link between taxing WM and the memory-effect has the form of an inverted U: too little and too much taxing both have little or no effect.
- We don’t know the optimal level yet
• Emotionality did not decrease after ‘recall without a dual task’ or ‘recall + complex arithmetic’, but it did after ‘recall + slightly complex arithmetic’
• This seems to imply the existence of an inverted U: not taxing WM or heavily taxing it during the recall does not change the memory, but taxing at a level somewhere in between does produce effects
The Effect of Beeps
• Theories about how a procedure such as EMDR works influence how the procedure is applied.
• The theories of ‘bilateral stimulation’ and ‘increase of interhemispheric communication’ inspired practitioners to replace eye movements with other forms of bilateral stimulation.
Eg alternating beeps
- However, registering beeps is a passive task that may not even tax WM.
- During this test, a probe is presented at alternating intervals and participants only needs to indicate whether they registered the stimulus
- Eye movements affected RT about three times as much as beeps did.
• When we tested the effects of beeps and eye movements on the emotionality and vividness of memories, we found no effect for emotionality in any of the three conditions; for vividness, the RT pattern was reflected.
• Vividness was not affected by ‘recall only’, but dropped substantially as a result of eye movements and a small but significant amount as a result of beeps.
• The effects of eye movements were about three times that of the beeps
• No studies have been conducted on the clinical effects of beeps, but earlier experimental data suggest that effective interventions need to tax the WM and the present experiments show that the beeps contribute little.
• They reduce the vividness of a memory but one needs to look very closely to see the effects, and the effect was only about one-third of the effect observed with the eye movements.
• Recently, we tested whether beeps might be as effective as eye movements in a clinical context
- Before and after each intervention the patient shortly recalled the image and rated its vividness and aversiveness.
- The largest decreases were found for recall + eye movements, and there was no effect at all for recall + beeps.
• Curiously, patients expressed a preference for beeps relative to eye movements and in written clarifications of their preferences; they mentioned that eye movements were “distracting” and “tiring”, and, ironically, this may signal the efficacy of the eye movements.
Mindfulness and Mindful Breathing
• Mindfulness-based cognitive therapy (MBCT) is effective in preventing relapse after treatment for depression, and treating patients with depression
• Like EMDR, MBCT is a package of interventions, but eye movements are a crucial element of EMDR, just like ‘mindful breathing’ (MB) is the core part of MBCT.
- In weekly group or individual sessions, patients are taught to focus their attention on breathing.
• Although EMDR and MBCT differ in many respects, they show a striking procedural parallel:
- both start with patients reporting disturbing thoughts or images;
- patients are instructed not to suppress the images, but to accept them; and
- patients are advised to perform another task while having those thoughts
- This made us curious about whether the WM theory could be used to explain how MB may work in MBCT.
• A first, cautious step was to find out whether MB taxes WM, and, if so, how this taxing compares to eye movements.
• This was done using two different RT tasks:
- a stimulus discrimination task and a random interval task
• Findings were identical: for both tasks, participants’ RTs increased when making eye movements and when practicing MB.
- Also eye movements and MB both significantly reduce memory emotionality
- Both interventions reduced emotionality of memories in study 1, and eye movements also reduced vividness, but MB did not (second experiment found that MB did)
• It therefore appears that eye movements and MB tax WM to the same degree and grosso modo both techniques affect vividness and emotionality of unpleasant memories.
