by Joye C. Anestis
The New York Times is really into providing topics for PBB lately. Last night, I discovered the provocatively titled article "Morphine May Help Traumatic Stress." We have spent a good amount of time here on PBB discussing PTSD in general, as well as the data on its treatment...and neither Mike nor I have ever come across an article promoting morphine as an effective treatment, so my curiosity was peaked. Turns out, the Times was reporting on some preliminary data about morphine as a sort of "morning-after pill" for trauma (to use the words of journalist Benedict Carey) that would prevent the development of PTSD. Prevention of PTSD is definitely an important national health goal (as is the prevention of any mental illness)...and the use of a pill to do so is intriguing. I mean, just think of the implications if individuals brought into the hospital for trauma could be given a pill to reduce their risk of developing PTSD (for another treatment that purports to prevent PTSD, read about Critical Incident Stress Debriefing - this treatment has proven to be harmful for clients). After reading the Times summary of the study, and assuming that the findings were probably overstated (as research findings generally are in the media), I looked up the original article, published in the prestigious New England Journal of Medicine (looks like NEJM is currently offering free full text here).
Apparently, an earlier study noted that morphine administration had protected children with burn injuries from developing PTSD (Saxe et al., 2001). A few other studies offer some support for this practice in adults (e.g., Bryant et al., 2009). The current authors (who are employed by the Naval Health Research Center), combed through the U.S. Navy-Marine Corps Combat Trauma Registry Expeditionary Medical Encounter Database (they abbreviate this: CTR EMED), a large database designed to document the records of casualties in the Iraq military theater during and after battle. They looked at the use of morphine during early trauma care for injured military personnel. Injured military personnel were identified as those brought to "forward medical treatment facilities" (the facilities closest to the point of injury) with injuries during Operation Iraqi Freedom (defined as the 36-month period from January 2004 through December 2006). The Navy-Marine Corps CTR EMED contained information from "medical encounter forms" used at these facilities. These forms include "demographic data, time of arrival at the facility, detailed information on the mechanism of injury, and comprehensive treatment data, including medications administered during early resuscitation and trauma care, dosages, route of administration, and interval between arrival at the facility and initiation of treatment" (p. 111). Information was also available on the severity of injury. PTSD diagnoses were obtained from the Career History Archival Medical and Personnel System and verified by reviewing medical records. PTSD assessment were made 1-24 months from the date of injury and were based on DSM-IV criteria.
Of the 696 personnel, 243 developed PTSD and 453 did not. 90% of them had an Injury Severity Scale Score of 16 or less (the highest score on the scale is a 75). The remaining 10% (i.e., > 16) were considered to have serious injuries. There were no significant differences on the mechanism of injury between the PTSD and non-PTSD groups. Morphine use was common in both groups of personnel. Use of other meds with psychotropic effects was uncommon. The authors used odds ratios to examine the association between morphine use and risk of PTSD. An odds ratio is a measure of effect size which can be used to measure the strength of association between 2 binary variables. The use of morphine directly after injury was significantly associated with a reduced risk of PTSD (odds ratio, 0.47; p < 0.001), and the significant association remained after adjusting for severity of injury. Multivariate-adjusted odds ratios for the association between morphine use and reduced risk of PTSD, adjusting for demographic and clinical variables (age, injury severity, amputation status, mechanism of injury, mild traumatic brain injury), were also significant (odds ratio, 0. 49; p < 0.001).
Unlike the definitive conclusions drawn by the Times, the article's authors are cautious in discussing these findings - noting that morphine use in trauma care may be protective against subsequent PTSD. The data they provide is preliminary, and several limitations prohibit any grand conclusions. In my opinion, the primary problem with this study is its observational nature. Because they looked at morphine use and subsequent PTSD diagnosis retrospectively, the authors cannot say that morphine use caused a lower risk for PTSD. A more rigorous study would have taken injured military personnel and randomly assigned them to morphine treatment or a no-morphine control group (although there are definite ethical considerations in doing this, including the provision of some equally effective, alternative pain management solution).
However, while we are a long way from firmly arguing for the use of morphine to prevent PTSD, the ideas behind its use in a preventative fashion are based on some really interesting theories. One proposed mechanism of morphine's effectiveness is the relationship between morphine and memory. It is proposed that such pharmacotherapy could "decrease or impede memory consolidation and the associated conditioned response to fear after a person goes through a traumatic event" (Holbrook et al., p. 111). So, one potential route of effectiveness is that morphine would prevent traumatic memories from being formed, or at least decrease the intensity of the memory so that it would not be as fearsome. Another contributing idea is that a reduction in perceived pain levels may lower risk. This idea is based on some studies which have found that self-reported pain levels immediately after serious injury were significantly associated with risk for PTSD (Bryant et al., 2009; Norman et al., 2008; Zatzick & Galea, 2007). It seems that the more painful an experience is perceived, the more likely PTSD is as an outcome...by manipulating pain perception, this risk is decreased. I would love to hear your thoughts on these 2 proposed mechanisms of action. I personally find them compelling and fascinating,but don't have the expertise to speak to them with any confidence. Anyone out there with some expertise in memory development want to chime in? What about potential costs vs. benefits of memory alteration as a treatment? Any thoughts on the pain perception theory? I'm looking forward to your thoughts!