Re:Retelling the Story

Sandra:

I do not, and never have, denied procedural differences between exposure and EMDR. I have, however, questioned whether the procedural differences actually mean that there are different mechanisms at work. This is an empirical question and there are methodological guidelines for how how you would go about demonstrating this. The strongest evidence would be to demonstarte what is referred to a "double dissociation," where you show that a single variable has the opposite effects on the the outcome for the two treatments. Ulirch has suggested a candidate for such a test: blockading endorphine receptors with naltrexone. There are published data to indicate that, at least in phobias, administration of naltrexone prior to conducting exposure reduces the efficacy of exposure relative to placebo. Ulrich has stated that there are pilot data suggesting the opposite is true for EMDR: That naltrexone enhances the efficacy of EMDR.

Now, if someone were to conduct a single experiment in which patients were randomly assigned to the four different conditions created by crossing psychological treatment (exposure therapy vs. EMDR) with medication condition (naltrexone vs. pbo) AND found that exposure plus placebo was superior to exposure plus naltrexone AND that EMDR plus naltrexone was superior to EMDR plus placeboe, THAT is the kind of data that would make me change my mind about whether EMDR and exposure share common mechanisms. Short of such data, however, it is (IMO) just speculation.

In your post, you describe a number of seperate events that might be part of a single overall trauma. Some of the examples you give are things that we would include as part of the trauma imagery. For example, we might very well include both the accident and the ambulence ride to the hospital following the accident in the same trial of imagery. So the difference in that case is simply whether you conduct treatment on different parts of the event as part of a single memory or as seperate memories targeted sequentially.

There are no data of which I'm aware that suggests that this would be a critical problem for exposure therapy. I would expect, on average, that exposure therapy would work just as well if you took a whole memory and worked on it repeatedly or broke it down into chunks that are worked on sequentially. The fact is, we routinely do both, depending on how long the memory is, whether certain parts of the memory are differentially distressing (so called "hot spots" get seperate focus and if there are more than one, get treated sequentially).

Other examples you give are things we wouldn't necessarily target with exposure at all. For example, I'm assuming that things such as "lies in the police report" and the "stupid lawyer" are things that provoke anger. We don't typically target anger with exposure therapy. We do have some data that indicate that simply treating PTSD results in a reduction of anger, without having to target it in treatment (Cahill et al., in press). At the present, the data are limited to the state-portion of the state-trait anger experession inventory, so we have no idea whether this anger is truely "trauma-related" or not. We just know that patients are less angry after treatment for PTSD, that this is true whether we treatmetn with exposure or with SIT (which is an effective stand alone treatment for anger), and that the benefits of treatment for PTSD on anger are present for people whose pretreatment anger is within normal limits and for those whose pretreatment anger levels is well above (i.e., 2 standard deviations above) the norm.

Just to be provocative, at the present time, there are no convincing data that exposure and SIT operate through different mechanisms. And in that case, the procedural differences between exposure and SIT are far greater than the procedural differences between exposure and EMDR.

I may be madening, but I try to be consistent.

Replies:

Re:Retelling the Story, by Sandra Paulsen Inobe PhD, 02/10/03

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