عادت کردن به بین جلسه و در جلسه در مواجهه درمانی طولانی مدت برای اختلال استرس پس از سانحه: یک رویکرد مدل سلسله مراتبی خطی

Prolonged Exposure Therapy is a frontline intervention for posttraumatic stress disorder, but the mechanisms underlying its efficacy are not fully understood. Previous research demonstrates that between- and within-session habituation of fear during exposure is associated with treatment outcome, but these calculations are historically performed with summary statistics such as mean subjective units of distress (SUDS). This question could be better assessed with an analytic technique that uses all SUDS measurements available within sessions. Hierarchical linear modeling was used to investigate the impact of treatment response on SUDS nested within therapy sessions nested within 14 patients. Symptom change (t = −2.43, p = .03) and responder status (t = −2.68, p = .02) predicted slope of SUDS across sessions, but did not reliably predict slope of SUDS within-session, indicating that high responders demonstrated differential between- but not within-session habituation. Thus, individuals who show greater habituation between treatment sessions may be more likely to respond to treatment.

Prolonged Exposure is a frontline intervention for posttraumatic stress disorder (PTSD) with substantial evidence supporting its efficacy for a variety of patient populations (Powers, Halpern, Ferenschak, Gillihan, & Foa, 2010; Rauch et al., 2009, Schnurr et al., 2007 and Tuerk et al., 2011). The factors associated with treatment efficacy are of considerable interest and debate (e.g. Bluett, Zoellner, & Feeny, 2014). Previous research demonstrates that habituation1 of fear is a key process in exposure and is associated with PE treatment outcome. In particular, previous findings have demonstrated that between-session habituation, or a decrease in patient-reported subjective units of distress (SUDS) between sessions, is an important contributor to symptom reduction. In several PE studies, greater reductions in mean and peak SUDS between the first and last imaginal exposure session of PE were associated with greater PTSD symptom reduction (Bluett et al., 2014Gallagher & Resick, 2012; Rauch, Foa, Furr, & Filip, 2004). Greater habituation between imaginal sessions one and two has also been shown to be a marker of treatment response (van Minnen & Hagenaars, 2002). Another study demonstrated that between-session habituation was associated with reduced PTSD symptoms both at treatment endpoint and at one-month follow-up (van Minnen & Foa, 2006). Additionally, a hierarchical clustering analysis revealed that the best treatment outcomes were associated with “high engagers/habituators”– individuals who showed high SUDS during the first imaginal exposure session and gradually declining SUDS over the course of the next six sessions (Jaycox, Foa, & Morral, 1998). Outcomes in this group were superior to the outcomes of the two other classes of response: high engagers/non-habituators and low engagers/non-habituators. These studies provide promising preliminary evidence that differences in SUDS between sessions are associated with positive treatment response. However, several studies of individuals with PTSD (Bluett et al., 2014; Pitman, Orr Altman, Longpre, Poiré, et al., 1996; Pitman, Orr Altman, Longpre, Poire, et al., 1996), and other disorders (Kozak, Foa, & Steketee, 1988; Lang & Craske, 2000; Meuret, Seidel, Rosenfield, Hofmann, & Rosenfield, 2012; Rowe and Craske, 1998 and Tsao and Craske, 2000) demonstrate positive treatment outcomes in the absence of between-session habituation. Thus, further research is needed to determine the relationship between treatment response and between-session habituation. Another habituation pattern that may be a beneficial component of PE is within-session habituation, or decline in SUDS over the course of an individual session. One PE study demonstrated that treatment responders showed greater within-session habituation than non-responders while listening to imaginal exposure at home, though not during the therapy session itself (van Minnen & Hagenaars, 2002). Another study found that amongst 106 individuals with various anxiety disorders, greater within-session habituation during the first exposure session was associated with lower risk for treatment dropout (Norton, Hayes-Skelton, & Klenck, 2011). Similarly, during the third exposure session, greater within-session habituation was associated with lower anxiety symptomatology at therapy endpoint (Norton et al., 2011). Thus, there is some evidence to suggest that a pattern of decreasing anxiety during a session of exposure is predictive of good treatment outcome. However, several studies show no evidence for the necessity of within-session habituation (Baker et al., 2010 and Bluett et al., 2014; Culver, Stoyanova, & Craske, 2012; Jaycox et al., 1998; Kozak et al., 1988Meuret et al., 2012; Pitman, Orr Altman, Longpre, Poiré, et al., 1996; Pitman, Orr Altman, Longpre, Poire, et al., 1996; Riley et al., 1995 and van Minnen and Foa, 2006; van Minnen & Hagenaars, 2002). Thus, there is mixed support for the association between within-session habituation and positive treatment response. In addition to habituation, several other markers of PE efficacy have been proposed. A recent investigation demonstrated that the perceived helpfulness of imaginal exposure homework had an indirect effect on the relationship between distress reduction and clinical outcome such that individuals with modest reductions in peak distress still experienced clinical improvement if they perceived homework to be helpful (Bluett et al., 2014). Reduced negative cognitions about the world and the self may also mediate treatment response (Foa & Rauch, 2004). Finally, distress tolerance has recently emerged as an important potential mechanism of change in exposure therapy (Craske et al., 2008 and Meuret et al., 2012). Fostering distress tolerance during exposure promotes the acquisition of inhibitory learning that weakens or negates the original conditioned stimulus-unconditioned stimulus expectancies (see Myers & Davis, 2002). While all these factors may contribute to successful treatment response, habituation remains the most consistent theoretical construct related to response in exposure therapy. Though several theories have been proposed, the question of what predicts success in PE could be better assessed by using analytic techniques that capitalize on the wealth of data that is available from standard PE treatment. During imaginal exposure in the standard PE protocol, SUDS is collected every five minutes. Given such a large number of data points, past studies (Bluett et al., 2014, Jaycox et al., 1998 and Rauch et al., 2004; van Minnen & Hagenaars, 2002) have used peak SUDS, mean SUDS, or another summary measure to estimate habituation, but no study to date has used the full extent of available data to model all of the variability in SUDS during imaginal exposure. The current analyses utilized all the SUDS data available in PE sessions from a small mechanistic study of PE to examine habituation both within and between sessions. Hierarchical linear modeling (HLM) is a multilevel modeling technique that accounts for the inherent nested nature of data generated by treatment studies. Unlike repeated measures ANOVA, HLM allows for different numbers of sessions between patients. In the current study, we modeled SUDS data points (level-one) nested within session (level-two), nested within patient (level-three). We then tested the effects of symptom change and treatment responder status at each level. We hypothesized that high responders would show greater reduction in SUDS than low responders both within session and between sessions.

In conclusion, the current study provides robust support for the importance of between-session habituation in PTSD treatment outcome. In addition, within-session habituation does not appear to be related to response. Instead, a pattern of slight increase in SUDS within a session is apparent in the overall sample, though not related to treatment response. As such, practitioners' efforts to optimize treatment should focus on those patients who are not showing reductions in SUDS across sessions. Indeed, discussion of within-session patterns of SUDS might include the fact that no change or even an increase in SUDS is not related to overall treatment response. Such patterns may represent engagement with the memory over the course of the session and suggest possible good outcomes for specific patients. Tracking SUDS changes across sessions can help practitioners monitor patient progress and can provide data to better guide decisions about implementing treatment modifications or enhancements.