The current study provides evidence that both the physical concerns and cognitive concerns anxiety sensitivity dimensions are uniquely associated with overall posttrauma stress symptoms, and that the cognitive concerns dimension may be especially important. This finding differs somewhat from past research that has found that only one of the dimensions predicts posttrauma stress symptoms (Asmundson & Stapleton, 2008
; Lang et al., 2002
; Vujanovic, Zvolensky, & Bernstein, 2008
). The mixed findings from past studies using an older version of the ASI may have been due to reliance on a measure that does not adequately measure anxiety sensitivity dimensions (Taylor et al., 2007
). The current study used a measure of anxiety sensitivity that was specifically designed to measure the dimensions of anxiety sensitivity, providing a stronger test of the contribution of each facet of anxiety sensitivity. However, there are differences between past studies and the current study, such as the use of clinical versus nonclinical samples, and the type of trauma. Regardless, the finding that the cognitive concerns dimension seems particularly relevant to posttrauma stress symptoms is consistent with clinical observations (Taylor, 2004
This study also found evidence that, cross-sectionally, anxiety sensitivity moderated the relationship between hyperarousal symptoms and reexperiencing symptoms, and between hyperarousal symptoms and numbing symptoms. Controlling for pre-shooting trauma levels did not eliminate the evidence of that anxiety sensitivity moderated the relationship between hyperarousal symptoms and reexperiencing symptoms, though it did partially explain the moderating role of anxiety sensitivity on numbing symptoms, and on numbing/avoidance symptoms. Contrary to predictions, anxiety sensitivity was not found to moderate the relationship between hyperarousal symptoms and avoidance symptoms when the avoidance cluster was examined alone. These findings might be due to the difference between the avoidance symptom cluster and other symptom clusters based on mode of processing. For example, Foa, Zinbarg, and Rothbaum (1992)
have suggested that avoidance is an effortful and strategic process used in response to intrusive symptoms, whereas numbing is an automatic analgesia response resulting from uncontrollable overstimulation (i.e., reexperiencing). Therefore, concern about the meaning of arousal symptoms may have more of an effect on processes that are automatic in nature. The findings from the current study may also provide support for the relevance of conceptualizing avoidance and numbing symptoms as being distinct clusters given the differential prediction of the interaction of ASI and hyperarousal on each cluster.
In sum, the moderating role of anxiety sensitivity found in this study is consistent with the view of hyperarousal as driving the course of posttrauma stress symptoms (Schell et al., 2004
), specifically when considering the observed specificity of the effects in the current study. Anxiety sensitivity appears to moderate the relationship of hyperarousal on other posttrauma stress symptom clusters in this study, but more convincing evidence of the moderating role of anxiety sensitivity would come from studies that examine the hypothesis prospectively or experimentally.
The effect of anxiety sensitivity appears modest in this study. Relevant to this issue, common method variance may have inflated the effect sizes in these analyses, including the estimation of the interaction effect. We note, however, that one of the predictors (i.e., hyperarousal) and the dependent variables were assessed using scales from the same measure (i.e., the DEQ), suggesting that the relationships between these variables are likely inflated due to common method variance. Thus, the reexperiencing and numbing measures are less methodologically distinct from the hyperarousal measure than they are from the anxiety sensitivity measure. Such strong relationships between the DEQ scales create stringent tests for examining the linear and moderating effects of anxiety sensitivity. Future research using multimethod assessment may be better able to estimate the magnitude of the linear and moderating effects of anxiety sensitivity. In addition, the effect sizes associated with anxiety sensitivity may be greater in clinical populations because of greater variance in the variables of interest. Evidence of a moderation effect of anxiety sensitivity is consistent with a functional relationship of hyperarousal with reexperiencing and numbing, but no predictions regarding how long it takes for the process to manifest were made. Thus, the concurrent assessment of anxiety sensitivity, hyperarousal, and the outcome variables (reexperiencing and numbing) may underestimate the magnitude of the relationships between these variables. Never-the-less, the evidence of a small moderation effect found in the current study does not, by itself, warrant targeting anxiety sensitivity in treatment or prevention.
Related to this issue, the measure of anxiety sensitivity is dimensional, but there is growing evidence that the latent structure of anxiety sensitivity is taxonic (e.g., Bernstein et al., 2006
). Research on the latent structure underlying the ASI-3 items is needed, as well as clarification regarding the moderating role of the anxiety sensitivity taxon.
A central limitation to the current study centers on restrictions in generalizing the findings to symptoms consistent with a PTSD diagnosis. The majority of the sample likely would not have a level of exposure to the mass shooting consistent with current conceptualizations of a Criterion A stressor, which precludes the possibility of a PTSD diagnosis. Follow-up analyses were restricted to only those students who were considered to be in the moderate to high exposure groups in order to determine whether the observed findings were relevant for participants in those groups while excluding those participants who would clearly not have met Criteria A.
The short latency between the campus shooting and the launch of the Time 2 assessment is a strength of the study because a large proportion of the sample completed the assessment within 30 days of the shooting. This time frame is consistent with the study’s focus on posttrauma stress symptoms, but raises questions about the applicability of these results to understanding PTSD, which requires the presence of symptoms for greater than 30 days. Thus, the symptoms assessed in the current study may be viewed as acute reactions to mass violence.
Another important limitation of this study is that the measure of posttrauma stress symptoms was not specifically designed to assess four symptom clusters (i.e., splitting the avoidance/numbing cluster). For example, the numbing cluster, as measured by the DEQ, only consists of two items since this cluster was not designed to be measured separately from the avoidance cluster. Another limitation is that anxiety sensitivity was only measured after the shooting. Although anxiety sensitivity is conceptualized as a relatively stable individual difference factor (Reiss & McNally, 1985
), the findings of the current study do not constitute evidence that a pre-trauma elevation in anxiety sensitivity is a risk factor for the development of PTSD symptoms. Because anxiety sensitivity was assessed posttrauma, the index used in this study might also reflect appraisals that depend upon the posttrauma context, including the individuals’ internal states. For example, anxiety sensitivity appears to increase after an unexpected panic attack (Schmidt, Lerew, & Joiner, 2000
). Thus, the findings of the study might be interpreted as implicating the valence of anxiety sensations, as perceived by the individual following the trauma. The degree to which these perceptions are influenced by stable individual difference factors that existed prior to the trauma is an open question for possible future research. There are some prospective studies, however, that do implicate pre-trauma levels of anxiety sensitivity (Keogh et al., 2002
; Asmundson et al., 2002
We also note that the sample consisted of only female undergraduate students taking an introductory psychology course, limiting the ability to generalize the current findings. This limitation is especially pertinent given research suggesting differences between females and males, both in terms of prevalence and chronicity of PTSD symptoms (see Norris, Foster, & Weisshaar, 2002), and in terms of the association between anxiety sensitivity and posttrauma stress symptoms (Feldner, Zvolensky, Schmidt, & Smith, 2008
). Limits to generalizability may also be associated with the nature of the traumatic experience of focus in the present study. Because all participants in the study completed the DEQ related to the mass shooting, results are limited to reactions to that singular traumatic event. In addition, the reported relationships between anxiety sensitivity and posttrauma stress symptoms in the current study are cross-sectional, precluding conclusions about the direction of effects. The specificity of the moderation effects observed, however, partially increases confidence in the view that hyperarousal leads to other posttrauma stress symptoms. Clearly, additional research is needed to better understand the structural relationship among PTSD symptom clusters.