سرکوب افکار مزمن و علائم پس از سانحه: داده های حمله تروریستی 11 مارس 2004 مادرید

Although a considerable number of people either witnessed directly or in the mass media the traumatic scenes of the terrorist attack that took place on March 11th, 2004 in Madrid, only a fraction of Madrid citizens developed posttraumatic symptoms. In this study, posttraumatic stress-related symptoms, degree of exposure, coping strategies related to the attack, and chronic attempts to avoid intrusive thoughts (i.e., thought suppression) were assessed in a general population Madrid sample (N = 503) 2–3 weeks after the attacks. Our results showed that participants with higher scores in chronic thought suppression exhibited higher levels of PTSD symptoms. Higher scores in chronic thought suppression also correlated positively with the use of avoidant coping strategies after the attacks. We discuss the possible common roots of avoidance of intrusive thoughts and avoidant coping strategies and the implications of this relationship for the emergence of stress-related symptoms as well as for public health policies.

Terrorist attacks are events that can be considered as an important source of traumatic responses (DiMaggio & Galea, 2006; Norris, Byrne, Diaz, & Kaniasty, 2001). Moreover, the fact that terrorism is directly provoked by humans whose only goal is to generate deaths, suffering, and horror may aggravate its psychological consequences (Danieli, Brom, & Sills, 2005). However, not all of those who are directly or indirectly exposed to this type of events develop substantial symptoms of stress or even posttraumatic clinical disorders. For instance, recent studies in community samples have shown that only a rather low percentage of people exposed to terrorist attacks develop clinically significant disorders as a consequence of the attack (e.g., Galea et al., 2003; Vázquez, Pérez-Sales, & Matt, 2006). Although the initial symptom levels are usually high in the first weeks after the attacks (e.g., Blanchard et al., 2004 and Muñoz et al., 2004; Silver, Holman, Mcintosh, Poulin, & Gil-Rivas, 2002), these initial responses return to previous levels for most of the people within weeks (Galea et al., 2003 and Miguel-Tobal et al., 2006; Shalev & Freedman, 2005). What makes some people vulnerable to developing posttraumatic symptoms? Recent meta-analyses (Brewin, Andrews, & Valentine, 2000; Ozer, Best, Lipsey, & Weiss, 2003) have identified several factors related to the characteristics of the traumatic episode (e.g., severity, sudden, repeated, and intentional events) and clinical and demographic factors (e.g., female gender, low socioeconomic status, previous psychiatric history, previous history of childhood abuse, and lack of social support) that increase the probability of developing stress-related symptoms. Vulnerability factors related to psychological mechanisms have also received attention as probable etiological components of psychopathological responses to traumatic events. Most of the psychological models of trauma-related responses have emphasized the fact that the magnitude of the responses depends on the way the event is subjectively appraised and is finally accommodated into the individual's self- and world-schemas (Janoff-Bulman, 1992). In processing threatening information, several factors, such as the ability to handle intrusive memories (Brewin, Dalgleish, & Joseph, 1996), the ability to provide meaning to the stressful experience (Davis, Nolen-Hoeksema, & Larson, 1998), or previous beliefs that one's psychological skills are effective to deal with stressful situations (Roussis & Wells, 2006), have all been found to play an important role in coping with traumatic events (see Brewin & Holmes, 2003; Dalgleish, 2004). Research on cognitive processes in stress-related symptoms has consistently found that certain coping strategies such as the use of effortful strategies to avoid thinking of the traumatic event (i.e., thought suppression), are usually not effective to adequately process emotional information (Horowitz, 1986; Lavy & van den Hout, 1990). The concept of thought suppression, originally developed by Wegner and his group (Wenzlaff, Wegner, & Roper, 1988), is particularly relevant as it highlights the consequences of employing avoidance as a strategy to cope with intrusive thoughts. In a classical paradigm to study thought suppression mechanisms, participants who are requested to suppress an image (e.g., a white bear) typically experience more intrusions in the subsequent period of time than participants who are told to think about such an image. Although the underlying mechanisms of this “rebound effect” are still under discussion (e.g., Liberman & Förster, 2000), this phenomenon has been often found in the literature (for a detailed discussion, see Wenzlaff & Wegner, 2000) and has been proposed as an explanation of why intrusive images are paradoxically maintained despite the individual's efforts to get rid of them. It has been suggested that thought suppression can be understood as either a state or a trait level. That is, some people could be chronically inclined to use thought suppression as a typical way of coping with undesired thoughts ( Wegner & Zanakos, 1994). According to this view, chronic thought suppression is defined as the general tendency or desire to suppress distressing thoughts. After traumatic experiences, trying to block intrusive cognitions and images might be experienced as a useful strategy in the short term by chronic suppressors. However, it might actually interrupt cognitive processing and, consequently, perpetuate the threatening cognitions and the anxiety associated with them. Preliminary evidence for such a relationship has been found in diverse groups of survivors. For example, a study with survivors of rape found that those who developed PTSD showed more difficulties suppressing rape-related thoughts and more frequent rebound experiences than the survivors without PTSD (Shipperd & Beck, 1999). Thought suppression has also predicted PTSD severity in samples of flood survivors (Morgan et al., 2001) and survivors of traffic accidents (Ehlers et al., 1998 and Ehlers et al., 2003). In evaluating the specific role of thought suppression as a maintenance factor, Mayou, Bryant, and Ehlers (2001) found that thought suppression assessed 3 months after a motor vehicle accident predicted the persistence of PTSD 3 years later. Similarly, Engelhard, van den Hout, Kindt, Arntz, and Schouten (2003) found that patients who showed higher levels of peritraumatic dissociation also showed higher levels of thought avoidance which, in turn, was associated with trauma-related symptoms. Coping research has also revealed a significant relationship between avoidance strategies and trauma-related symptoms, which is highly relevant in this discussion, as chronic attempts to suppress distressing thoughts might be considered a specific type of avoidant coping strategy. For example, studies with brain injury patients (Bryant, Marosszeky, Crooks, Baguley, & Gurka, 2000) and victims of traffic accidents (Bryant & Harvey, 1995) have found an association between patients’ avoidant coping style and PTSD severity. In a sample of burned patients, a pattern of avoidant behaviors at discharge predicted the severity of intrusions 4 months later even after controlling for initial level of intrusions (Lawrence, Fauerbach, & Munster, 1996). An additional study with victims of physical and sexual assault found that specific avoidant coping strategies such as denial by fantasy or mental undoing (e.g., trying to erase memories of the assault) were associated with the persistence of PTSD symptoms (Valentiner, Foa, Riggs, & Gershuny, 1996). Thus, it seems that there is a consistent relationship between the use of avoidant cognitive and behavioral strategies and the severity and persistence of stress-related symptoms. However, the relationship between cognitive processes and behavioral avoidance strategies remains relatively unexplored in the context of PTSD research. The goal of the present study was to investigate the relationship between the tendency to suppress unwanted thoughts and both posttraumatic symptomatology and specific trauma-related coping behaviors in the immediate weeks after the Madrid 11-M terrorist attack. On March 11th 2004, exactly 2.5 years after the September 11 attacks on the United States, an unprecedented terrorist attack targeted the citizens of Madrid (Spain). That day, a series of bombs exploded almost simultaneously in three different train stations of the metropolitan area of Madrid, killing 191 and wounding more than 1500 people. The September 2001 attacks on American soil instigated the analysis of psychological effects of large scale terrorist attacks on general population (Galea et al., 2002, Schlenger et al., 2002 and Schuster et al., 2001). However, perhaps because of the difficulty of designing this kind of study in an emergency setting (North & Pfefferbaum, 2002), until now the works on the impact of terrorist attacks have focused almost totally on the symptoms and prevalence of psychological disorders, and they lack information on the role of the psychological processes involved in such naturalistic traumatic situations (Mehl & Pennebaker, 2003). Thus, when designing our study a few days after the attack, we included not only clinical measures (e.g., a PTSD questionnaire) but also, among other measures, a self-report measure of a cognitive process (i.e., chronic thought suppression) that is hypothetically related to vulnerability to developing clinical symptoms. Our main hypotheses were twofold. First, it was hypothesized that higher levels of thought suppression would be positively correlated to higher severity of trauma-related symptoms. Our second hypothesis was that higher scores on chronic thought suppression would, in turn, be positively associated with a pattern of avoidant behaviors and cognitions specifically related to the terrorist attack.

3.1. Description of the sample Data from 503 participants were initially included in the study. Twenty participants (4.0%) reported having been directly exposed to the terrorist attack, and seven (1.4%) suffered injuries as a consequence of the attack. Seventy-three participants (14.5%) were daily users of the subway lines that were affected by the attack, and 218 participants (43%) knew someone affected by the attack; 116 (23%) were friends of some of the direct victims, whereas 32 participants (6.4%) were relatives of someone directly affected by the attack. 3.2. Posttraumatic symptoms Table 1 shows the means and standard deviations of posttraumatic symptoms assessed by the PCL-C, which includes the PCL total score and its three subscales (i.e., Intrusions, Avoidance, Hyperarousal). In our sample, the mean PCL-C total score was 31.9 (S.D. = 12.9). Using the standard cut-off scores suggested for the PCL (Blanchard et al., 2004; Ruggiero, Del Ben, Scotti, & Rabalais, 2003), 13.3% of the participants scored 44 or above in the PCL-C total scores, whereas 7.2% of the sample scored 50 or above.