Denise Sloan, associate director at the US National Center for PTSD, has produced many fine publications on therapeutic writing.  However I think she has surpassed herself with her most recent:

Sloan, D. M., B. P. Marx, et al. (2012). "Written exposure as an intervention for PTSD: A randomized clinical trial with motor vehicle accident survivors"  Behaviour Research and Therapy 50(10): 627-635. The present study examined the efficacy of a brief, written exposure therapy (WET) for posttraumatic stress disorder (PTSD).  Participants were 46 adults with a current primary diagnosis of motor vehicle accident-related PTSD. Participants were randomly assigned to either WET or a waitlist (WL) condition. Independent assessments took place at baseline and 6-, 18-, and 30-weeks post baseline (WL condition not assessed at 30 weeks). Participants assigned to WET showed significant reductions in PTSD symptom severity at 6- and 18-week post-baseline, relative to WL participants, with large between-group effect sizes. In addition, significantly fewer WET participants met diagnostic criteria for PTSD at both the 6- and 18-week post-baseline assessments, relative to WL participants. Treatment gains were maintained for the WET participants at the 30-week post baseline assessment. Notably, only 9% of participants dropped out of WET and the WET participants reported a high degree of satisfaction with the treatment. These findings suggest that a brief, written exposure treatment may efficaciously treat PTSD. Future research should examine whether WET is efficacious with other PTSD samples, as well as compare the efficacy of WET with that of evidence-based treatments for PTSD.

This is exciting territory - "a brief, written exposure treatment" that can "efficaciously treat PTSD".  Remember (apart from witnessing trauma involving someone else), "being involved in a life-threatening accident" is likely to be the most commonly experienced trauma in Western societies (Kessler, Sonnega et al. 1995).  Previous research on expressive writing hasn't been able to show effective help for PTSD.  Just last year Sloan & colleagues - in their paper "A test of written emotional disclosure as an intervention for posttraumatic stress disorder" - failed to show benefit from getting PTSD sufferers to use written emotional disclosure.  So what has been done differently this time?  Well there were hints from the team's earlier work as to what should be tried next.  So in their paper "Peritraumatic dissociation and experiential avoidance as predictors of posttraumatic stress symptomatology", they had showed that "experiential avoidance" (attempts to avoid thoughts, feelings, memories, physical sensations, and other internal experiences - even when doing so creates harm in the long-run) is important in understanding the problems faced by PTSD sufferers.  Actually - and this is very interesting when considering the possible value of therapeutic writing for other psychological difficulties - experiential avoidance is likely to be of importance in many other psychological difficulties as well - see, for example "Experiential avoidance as a generalized psychological vulnerability".  In their papers "Further examination of the exposure model underlying the efficacy of written emotional disclosure" and "Does altering the writing instructions influence outcome associated with written disclosure?", Sloan et al had made it look likely that, if standard 20 minutes x 3 therapeutic writing instructions didn't cut the mustard, it would be worth seeing if more prolonged and more emotionally intense instructions might be more effective.  And that's what they have done in this most recent paper.  They wrote: "Through additional treatment development work, we determined that five, 30-min sessions would be sufficient to produce signi!cant reductions in arousal and negative affect among participants meeting diagnostic criteria for PTSD. Based on this initial pilot work, we made some other changes to the treatment protocol, including the addition of psychoeducation and treatment rationale components to the first session. The psychoeducation component includes information on symptoms of PTSD and other maladaptive behaviors that maintain these symptoms (e.g., avoidance). The treatment rationale emphasizes the importance of confronting the trauma memory, rather than avoiding or attempting to avoid, and the use of writing as a means of confronting the trauma memory. In addition, based on prior study findings (Sloan et al., 2005, 2007), we modified the writing instructions, such that participants are directed to write about the same trauma memory during each session and focus on the details of the trauma, with particular attention to felt emotions, the meaning of the traumatic event, and 'hot spots'."

For more on this, see tomorrow's post "Written exposure therapy: how do you do it?"