Habituation of distress during exposure and its relationship to treatment outcome in post-traumatic stress disorder and prolonged grief disorder.

Background: Reliving distressing memories is a core component of treatments for post-traumatic stress disorder (PTSD) and prolonged grief disorder (PGD). There is little understanding of how reliving these memories functions in the treatment of these disorders. Objective: This study investigated whether reliving functions comparably in the treatment of PTSD and PGD, and whether it is comparably related to treatment outcome. Method: This study conducted a reanalysis of patients with either PTSD ( n  = 55) or PGD ( n  = 45) who underwent treatments that comprised at least four sessions of reliving memories of either their traumatic experience or the loss of the deceased person. Results: PTSD participants displayed greater habituation of distress across sessions during reliving than PGD participants. Between-session reduction in distress during reliving was associated with symptom remission in PTSD, but this pattern was not observed in PGD. Conclusion: This pattern of findings indicates that although reliving appears to be a useful strategy for treating both PTSD and PGD, this strategy does not function comparably in the two conditions and may involve distinct mechanisms.