Acute stress disorder: A critical review of diagnostic issues

Pergamon

Clinical Psychology Review, Vol. 17, No. 7, pp. 757-773, 1997 Copyright @ 1997 Elsevier Science Ltd Printed in the USA. All rights reserved 0272-7358/97 $17.00 * .00

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ACUTE STRESS DISORDER: A CRITICAL REVIEW OF DIAGNOSTIC ISSUES Richard A. Bryant and Allison G. Harvey University of New South Wales

ABSTRACT. Acute stress disorder (ASD) is a recently developed diagnosis that describes

posttraumatic stress reactions that occur in the first month following a trauma. Diagnostic criteria include dissociative, intrusive, avoidance, and arousal symptoms. ASD was driven by the proposal that trauma leads to dissociative reactions, and these are predictive of longer-term psychopathology. This paper reviews a series of anomalies in the diagnostic criteria, highlights" discrepancies between criteria for ASD and posttraumatic stress disorder (PTSD), and illustrates the lack of empirical evidence for some assumptions inherent in the conceptualization of ASD. It is argued that future revisions of ASD criteria need to be based on empirical evidence of acutely traumatized individuaL~. © 1997 Elsevier Science Ltd

ONE OF the new diagnoses introduced in the latest edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-1V;, American Psychiatric Association, 1994) was acute stress disorder (ASD). This diagnosis appears in the anxiety section of the manual and was conceptualized as an acute f o r m of posttraumatic stress disorder (PTSD) that occurs within 2 days and 4 weeks of a traumatic experience, after which time a PTSD diagnosis should be considered. However, there are significant theoretical and diagnostic differences between DSM-IVconceptualizations of ASD and PTSD. Although ASD is regarded as an acute f o r m of PTSD, ASD is distinguished from PTSD by its emphasis on dissociative symptoms. In contrast to PTSD, a diagnosis of ASD requires that the individual satisfy at least three dissociative symptoms. In addition, and m o r e consistent with PTSD diagnosis, the individual must also experience intrusive, avoidance, and arousal symptoms. ASD was purportedly included in DSM-IV in recognition of the potentially high levels of distress that individuals can experience in the acute t r a u m a phase. In addition, drawing on research showing a relationship between acute stress reactions and PTSD, ASD is r e g a r d e d as a predictor of longer-term posttraumatic psychopathology (Classen, K o o p m a n , & Spiegel, 1993; K o o p m a n , Classen, Cardena, & Spiegel, Correspondence should be addressed to Richard A. Bryant, School of Psychology, University of New South Wales, NSW, 2052, Australia. E-mail: [email protected].

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1995; Koopman, Classen, & Spiegel, 1994). At present, however, little empirical work has been conducted to support these claims (Koopman et al., 1995). This paper reviews the diagnostic criteria of ASD, and highlights a n u m b e r of shortcomings in the current description and theoretical basis of this acute trauma condition. THE STRESSOR DEFINITION

The Objective Definition The diagnostic criteria for ASD commences with the requirement that the individual has experienced or witnessed an event that has been threatening to either themselves or another person. Further, it prescribes that the "person's response involved intense fear, helplessness, or h o r r o r " (American Psychiatric Association, 1994, p. 431). This definition is identical to the stressor definition of PTSD. The relative contributions of the objective and subjective components of the stressor have been strongly debated in recent years. Although diagnostic reliability and homogeneity may be increased with an objective definition of the stressor, there is strong evidence that a stringent definition of the stressor severity would lead to false negative diagnoses (Snow, Stellman, Stellman, & Sommer, 1988). There are many examples of PTSD symptoms occurring following less severe traumas (Burstein, 1985; Helzer, Robins, & McEvoy, 1987). Further, there have been numerous reports that emphasize the importance of perceived threat in predicting PTSD (Bryant & Harvey, 1995a; Mikulincer & Solomon, 1988; Speed, Engdahl, Schwartz, & Eberly, 1989). Accordingly, DSM-IVadopted the position that the definition of the stressor should involve both objective and subjective dimensions (March, 1993). Use of this definition in ASD is somewhat supported by findings that acute stress responses are associated with both severe stressors (Marmar et al., 1994) and subjective perceptions of threat (Bryant & Harvey, 1996).

The Subjective Definition The subjective c o m p o n e n t of the stressor definition is problematic, however, in the context of the dissociative cluster of symptoms. The first dissociative symptom cited in DSM-IV is "a subjective sense of numbing, detachment, or absence of emotional responsiveness" (American Psychiatric Association, 1994, p. 432). Although incidence of this symptom has not been rigorously indexed in studies to date, there is some evidence that an absence of emotional response can occur in the acute trauma phase (Feinstein, 1989; Noyes, Hoenk, Kuperman, & Slymen, 1977). T h e r e appears to be an inherent inconsistency in the juxtaposition of the requirement of a fearful perception of the event and the experience of emotional numbing. For example, an individual who has survived an earthquake but reports no salient emotional response to this event would not satisfy the stressor criterion for ASD. It is possible, however, that this individual's lack of emotional response may be attributed to a dissociative reaction to the trauma. Thus, a strict adherence to the DSM-1Vcriteria may result in false negative diagnoses. Although this potential problem also exists in the diagnosis of PTSD, which includes the symptom of emotional numbing, it appears to be a more p r o m i n e n t difficulty in ASD because of the requirement that diagnosed individuals must display dissociative symptoms. We suggest that modifying the description of the response to the stressor to include behavioral manifestations of distress (such as nonresponsiveness or detachment) may reconcile, to some extent, the anomaly of dissociative responses and the requirement that the individual responds with fear or helplessness.

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DISSOCIATIVE SYMPTOMS

Theoretical Perspective of Dissociation The distinctive nature of ASD lies in its emphasis on dissociative reactions to the trauma. Whereas PTSD acknowledges possible inclusion of amnesia of the trauma or feelings of detachment, these symptoms are not necessary for a diagnosis of PTSD. The diagnosis of ASD, however, requires that the individual have at least three of the following: (a) a subjective sense of numbing or detachment, (b) reduced awareness of their surroundings, (c) derealization, (d) depersonalization, or (e) dissociative amnesia. T h e underlying theory of ASD is that dissociation is a primary coping mechanism for managing traumatic experiences. Tracing its historical roots to Janet's (1907) theory of dissociation, this theory proposes that individuals minimize the adverse emotional consequences of trauma by restricting their awareness of the experience (van der Kolk & van der Hart, 1989). Such reduction in awareness of the traumatic experience can be manifested in perceptual alterations, m e m o r y impairment, or emotional d e t a c h m e n t from one's environment (Cardena & Spiegel, 1993). The proposal that individuals attempt to manage overwhelming anxiety associated with a trauma is consistent with Horowitz's (1986) emphasis on denial as a primary posttraumatic coping strategy. The role of dissociative responses has recently been integrated into cognitive network models of PTSD (Foa & Hearst-Ikeda, 1996). Network models posit that following a trauma, fear structures develop that contain mental representations of the traumatic experience and are characterized by excessive threatrelated beliefs (Foa & Kozak, 1986). It is proposed that these fear networks result in an attentional bias to threat-related material, and can explain such posttraumatic symptoms as intrusive memories, hypervigilence, and avoidance. This model suggests that adaptive recovery from a trauma depends on two conditions. First, the fear structure must be activated so that the cognitive schema can be modified. Second, there needs to be introduction of new information that challenges the fear-related schema. According to this theory, resolution of posttraumatic stress is impaired if strategies are employed that prevent the individual from accessing the fear networks and processing the affectively-laden memories. It has been proposed that initial dissociative responses may impede activation of the fear structures, and this impaired emotional processing may lead to chronic PTSD (Foa & Hearst-Ikeda, 1996). Consistent with this theory are findings that traumatized individuals display disorganized and fragmented memories (Foa, Molnar, & Cashman, 1995) and have overgeneral memories of their trauma (McNally, Lasko, Macklin, & Pitman, 1995).

Empirical Evidence of Dissociation T h e r e are many reports of dissociative symptoms during the acute trauma phase. A sense of numbing (Feinstein, 1989; Noyes et al., 1977) and reduction in awareness of one's environment (Berah,Jones, & Valent, 1984; Hillman, 1981; Titchener & Kapp, 1976) are reportedly c o m m o n during a traumatic experience. Derealization refers to the perception that one's environment is unreal or dreamlike. This reaction has been reported in 40% of earthquake survivors (Cardena & Spiegel, 1993), 30% of accident survivors (Noyes & Kletti, 1977), and 53% of witnesses of an execution (Freinkel, Koopman, & Spiegel, 1994). Depersonalization involves the sense that one's body is detached or one is seeing himself/herself from the outside. This experience has been reported in 25% of earthquake survivors (Cardena & Spiegel, 1993), 31% of accident

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survivors (Noyes et al., 1977), 54% of airline disaster survivors (Sloan, 1988), 26% of prisoners of war (Siegel, 1984), and 40% of execution witnesses (Freinkel et al., 1994). Finally, dissociative amnesia has been reported in 29% of earthquake survivors (Cardena & Spiegel, 1993), 57% of ambush victims (Feinstein, 1989), 61% of tornado survivors (Madakasira & O'Brien, 1987), and 5% of World War II combatants (Torrie, 1944). These reports indicate that dissociative responses are c o m m o n in the acute phase of a traumatic experience. Frequency of dissociative symptoms immediately following a trauma does not support the p r o m i n e n c e of this cluster of symptoms in the diagnosis ofASD. Horowitz (1986) has argued that dissociative responses are common, and potentially adaptive, short-term reactions to a trauma, and can subsequently lead to adequate resolution of the traumatic experience. A major reason for emphasis on dissociative symptoms in the diagnosis of ASD is the extent to which they predict subsequent PTSD. Numerous studies have reported that dissociative reactions at the time of trauma are predictive of PTSD diagnosis (Holen, 1993; Koopman et al., 1994; Marmar et al., 1994; McFarlane, 1986; Shalev, Orr, & Pitman, 1993; Shalev, Peri, Canetti, & Schreiber, 1996; Solomon & Mikulincer, 1992; Solomon, Mikulincer, & Benbenistry, 1989). In one of the first studies to investigate this issue, Holen (1993) found that the peritraumatic dissociative responses in survivors of the North Sea oil rig disaster predicted subsequent adjustment. Solomon et al. (1989) reported that numbing in the acute trauma phase accounted tor 20% of the variance of subsequent PTSD. Factor analytic studies have also provided support for the association between dissociative responses and PTSD. In an analysis of DSM-III-R symptoms of PTSD in female assault victims, symptoms loaded on arousal-avoidance, numbing, and intrusion. Numbing, which included numbing of feelings, detachment from others, loss of interest, and a sense of foreshortened future, most accurately distinguished those individuals with PTSD from those without PTSD 3 months after the assault (Foa, Riggs, & Gershuny, 1995). It needs to be recognized, however, that most of these studies have collected data on acute dissociative reactions retrospectively (Holen, 1993; Marmar et al., 1994; McFarlane, 1986; Solomon et al., 1989). This methodology casts serious doubts over the extent to which current symptomatology influenced retrospective reports of their trauma reactions. The tendency for m e m o r y for trauma to change over time is well d o c u m e n t e d (Foa, et al., 1995; Wagenaar & Groeneweg, 1990). Further, there is evidence that m e m o r y distortion for traumatic events is influenced by PTSD symptomatology (Southwick, Morgan, Nicotaou, & Charney, 1997). It is possible that trauma survivors who are more disturbed recall more dissociative-type reactions in the acute trauma phase because their recall of the trauma will be affected by their current mood. If this is the case, it would not be surprising that retrospective reports of peritramnatic dissociative experiences predicted severity of later PTSD. Accordingly, the relationship between peritraumatic dissociative reactions and subsequent PTSD must be evaluated on the basis of prospective studies. T h r e e prospective studies have recently investigated the relationship between initial dissociative symptoms and subsequent PTSD (Dancu, Riggs, Hearst-Ikeda, Shoyer, & Foa, 1996; Koopman et al., 1994; Shalev et al., 1996). Although Koopman et al. (1994) did not diagnose ASD, acute dissociative symptoms better predicted PTSD than initial anxiety symptoms (Spiegel, Koopman, Cardena, & Classen, 1996). Similarly, Shalev et al. (1996) reported peritraumatic responses 1 week posttrauma predicted PTSD diagnosis 6 months later. The relationship between initial dissociation and PTSD does not appear to be straightforward. Dancu et al. (1996) found that whereas early

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dissociative responses are linked to persistent PTSD in nonsexual assault victims, this relationship was not observed in rape victims. This study found that initial dissociative responses following rape were related to posttraumatic psychopathology. This finding supports the hypothesis that dissociation may be associated with general psychopathology rather than specifically to PTSD. A retrospective investigation of ASD following motorvehicle accidents found that dissociation was not associated with subsequent PTSD (Barton, Blanchard, & Hickling, 1996). Further, Holen (1993) reported that whereas peritraumatic reactions were predictive of the short-term outcome, they were less important in contributing to longer-term adjustment. In short, although there are initial indications that suggest a relationship between peritraumatic dissociation and PTSD, there is still insufficient empirical evidence that ASD is directly linked to PTSD. Further prospective studies are required that delineate the relative power of each of the symptom clusters of ASD to predict subsequent PTSD. Previous studies of dissociative reactions following trauma are also limited, to varying degrees, by their reliance on measures that have not been adequately validated. Use of questionnaires that p u r p o r t to index dissociative reactions is the p r e d o m i n a n t means by which peritraumatic dissociation is indexed. These measures have not been sufficiently validated against clinician judgements, and it is unknown what factors mediate e n d o r s e m e n t of items on dissociation questionnaires in the posttraumatic phase. Such lack of development of adequate measurement procedures (see later) underscores the need for caution in interpreting previous findings concerning peritraumatic dissociation.

Ambiguities in Diagnosing Dissociation The role of dissociation in ASD is further complicated by the ambiguity concerning when the dissociative response occurs. According to DSM-IV,, the dissociative symptoms may occur "either during or after experiencing the distressing event." This flexible timeframe for the dissociative symptoms is in contrast to the r e q u i r e m e n t that the intrusive, avoidance, and arousal symptoms need to be experienced as ongoing problems. Further, it is in contrast to the requirement that the disturbance arising from the ASD persists for a minimum of 2 days after the trauma. Much of the research that has d o c u m e n t e d a relationship between initial dissociative reactions and subseq u e n t PTSD has not clearly defined when the dissociative responses occurred (Koopman et al., 1994; Marmar et al., 1994; McFarlane, 1986; Shalev et al., 1993; Solomon et al., 1989). Although it is theorized that peritraumatic dissociation is predictive of PTSD, there are insufficient data to indicate the extent to which short-lived or persistent dissociation is predictive. Transient dissociative responses are reportedly c o m m o n during the traumatic experience (Cardena & Spiegel, 1993; Noyes & Kletti, 1977; Noyes et al., 1977; Sloan, 1988) and may not necessarily be indicative of subsequent psychopathology. Further, alterations in attentional focus can be experimentally elicited with minimally distressing stimuli (Kramer, Buckhout, & Eugenio, 1990; Maas & Kohnken, 1989). In terms of a cognitive model of PTSD, dissociative symptoms that are transient should not necessarily impede emotional processing of the traumatic experience. On the other hand, persisting dissociation would be expected to impede activation of fear structures and may contribute to longer-term psychopathology. To differentiate normal and pathological reactions, there is a need to delineate the degrees to which dissociative symptoms that occur at the time of the trauma and those that occur in the days following the trauma predict subsequent

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PTSD. The stipulation that dissociative symptoms that occurred at any time satisfies the ASD criteria may be ovefinclusive. A stronger empirical basis for the duration of dissociative symptoms would clarify the role that they should have in the ASD diagnosis. T h e r e is also ambiguity c o n c e r n i n g the required severity of alterations in awareness that are necessary in order to satisfy dissociative criteria. As Hilgard (1977) has pointed out in his seminal work on dissociation, dissociative-type experiences are c o m m o n p l a c e and occur at many points on a c o n t i n u u m of severity (see Kihlstrom, Glisky, & Angiulo, 1994). F u r t h e r m o r e , studies that have employed the Dissociative Experiences Scale (DES; Bernstein & Putnam, 1986) have indicated that mild dissociative experiences are c o m m o n l y reported by nonclinical populations (Frischholz et al., 1992; Gilbertson et al., 1992; Ross, Joshi, & Currie, 1990). Consistent with experimental findings that alterations in awareness can occur during exposure to stress (Kramer et al., 1990; Maas & Kohnken, 1989), it is likely that mild alterations in attention c o m m o n l y occur during traumatic experiences. In contrast to the stipulation that intrusive, avoidance, and arousal symptoms n e e d to be " m a r k e d " or "persistent," there is no direction in DSM-IV that the dissociative symptoms n e e d to be experienced at a significant level of severity. This ambiguity may further result in an overinclusive definition of dissociation. To date there are no empirical data to inform us of the discriminatory power of the specific dissociative symptoms. Is there any overlap between the dissociative symptoms? For example, it is possible that traumatized individuals who report amnesia of the event may do so because reduced awareness of their surroundings impaired their encoding of the event. There is experimental evidence to indicate that during stressful experiences attentional resources are restricted (Kramer et al., 1990; Maas & Kohnken, 1989). Whether such attenfional narrowing is a result of heightened distractability or attention to specific threatening details, there is a consequent reduction in encoding. It appears repetitive to identify both awareness reduction and amnesia in an acutely traumatized person if the former is actually the mechanism by which they could not recall aspects of the trauma. I f a strict definition of dissociative amnesia is to be adopted, the content of the m e m o r y is available to the individual but temporarily inaccessible (Kihlstrom et al., 1994). That is, the need to minimize awareness of the traumatic recollections has resulted in retrieval processes being impaired. A person does not suffer dissociative amnesia if they do not recall material because it was not adequately encoded. That is, two processes may mediate a report of poor recall of the trauma. Failure to distinguish between encoding and retrieval may lead to a single symptom being mistakenly identified as multiple dissociative responses. Overall, the r e q u i r e m e n t that three dissociative symptoms be present to enable a diagnosis of ASD is based on a theoretical premise that currently lacks strong empirical support. Although there is preliminary evidence that initial dissociation is an i m p o r t a n t posttraumatic response, available evidence does not indicate that three acute dissociative symptoms are effective predictors of PTSD. Studies are required that assess the sensitivity and specificity of the acute dissociative symptoms to predict later PTSD. In the spirit of DSM-IV, the specification of the n u m b e r and type of acute dissociative symptoms required for a diagnosis of ASD should be empirically d e m o n strated in order to provide the optimal index of pathological acute response to a traumatic experience.

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REEXPERIENCING SYMPTOMS

Role of Reexperiencing in ASD The DSM-IV diagnosis of ASD requires that the trauma "is reexperienced in at least one of the following ways: recurrent images, thoughts, dreams, illusions, flashback episodes, or a sense of reliving the experience; or distress on exposure to reminders of the traumatic event" (American Psychiatric Association, 1994, p. 432). Reexperiencing symptoms have often been recognized as the hallmark symptoms of PTSD (Calhoun & Resick, 1993). Similarly, they have been commonly observed in the acute phase of a trauma (Bryant & Harvey, 1996; Kilpatrick & Resnick, 1993; Shalev, 1992). It is recognized by most models of posttraumatic stress that emotional processing of the trauma can be facilitated by intrusive thoughts and images (Foa & Hearst-Ikeda, 1996; Horowitz, 1986). It is proposed that reexperiencing symptoms allow the individual to process the trauma-related schema by allowing activation and modification of the schema. In this sense, acute reexperiencing symptoms are conceptualized as potentially adaptive. Consistent with this proposal, there is evidence that intrusive recollections of the trauma are not strong predictors of ongoing PTSD (McFarlane, 1988; Perry, Difede, Musngi, Frances, &Jacobsberg, 1992; Shalev, 1992). Accordingly, it has been postulated that persistent, rather than initial, intrusive recollections of the trauma are associated with posttraumatic psychopathology (Ehlers & Steil, 1995). There is also evidence, however, that reexperiencing symptoms in the immediate trauma phase can be predictive of persistent PTSD (Rothbaum, Foa, Riggs, Murdock, & Walsh, 1992). According to network models of trauma response, initial intrusions can result in avoidance activity that impedes activation and modification of the fear network (Creamer, Burgess, & Pattison, 1992). This model would suggest that the extent to which initial intrusions are predictive of later PTSD depends, in part, on the presence of avoidance during the acute trauma phase.

Reexperiencing in ASD and PTSD Although the description of reexperiencing symptoms in the ASD diagnosis appears similar to the parallel cluster of symptoms in the PTSD diagnosis, the two clusters are differentiated in two important ways. First, whereas the PTSD diagnosis stipulates that reexperiencing symptoms must cause the individual distress, the ASD diagnosis makes no mention of the negative emotional response to the traumatic thoughts or images. There is evidence that individuals vary markedly in their subjective response to intrusive recollections of trauma. For example, whereas terrorist attack survivors reported equivalent frequencies of intrusive memories within the first week of the attack, they reported variable levels of distress in response to these memories (Shalev, Schreiber, & Galai, 1993). Similar variations in distress have been reported in motorvehicle accident survivors (Ehlers & Steil, 1995). Failure of DSM-IVto include distress as a response to reexperiencing symptoms is inconsistent with evidence that not all unwanted thoughts are unpleasant (Rachman & de Silva, 1978), and the finding that acute stress is mediated by the extent to which individuals fear their memories of the trauma (Bryant & Harvey, 1996). Second, unlike the PTSD diagnosis, the ASD diagnosis does not require that the reexperiencing be unwanted or involuntary. Intrusive thoughts have been reported by 39% of earthquake survivors (Cardena & Spiegel, 1993), 71% of airline crash survivors (Sloan, 1988), and all survivors of a military ambush (Feinstein, 1989). Despite these figures, the DSM-1V diagnostic cri-

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teria do not refer to the uncontrollable nature of reexperiencing symptoms. This omission in the ASD diagnosis appears inconsistent with findings that controllability and frequency of unwanted thoughts are distinct factors (Parkinson & Rachman, 1981; Rachman & de Silva, 1978). Further, there is evidence that poor control of intrusive posttraumatic memories is associated with elevated distress (Harvey & Bryant, 1997). T h e r e does not appear to be a theoretical rationale or empirical evidence for not requiring posttraumatic thoughts to be involuntary in an ASD diagnosis, while at the same time requiring involuntariness of intrusions in a PTSD diagnosis. The role of reexperiencing symptoms in the acute trauma phase, and their contribution to persistent PTSD is poorly understood. Available evidence suggests that the distressing and intrusive nature of reexperiencing symptoms may be associated with more severe posttraumatic symptomatology. Future modifications of the ASD definition may need to consider changing the current description of reexperiencing symptoms to establish consistency between ASD and PTSD descriptions. The current discrepancy renders any comparison between reexperiencing symptoms in ASD and PTSD questionable.

AVOIDANCE SYMPTOMS Diagnostic criteria for ASD stipulates that the individual must display "marked avoidance of stimuli that arouse recollections of the trauma." Such avoidance includes avoidance of thoughts, feelings, activities, conversations, and people that may remind the individual of their traumatic experience (American Psychiatric Association, 1994, p. 432). Active avoidance in the acute phase has been reported by 30% of earthquake survivors (Cardena & Spiegel, 1993), 10% of tornado survivors (North, Smith, McCool, & Lightcap, 1989), and 50% of motor-vehicle accident survivors (Bryant & Harvey, 1996). In most cognitive models of PTSD (Creamer et al., 1992; Foa & Kozak, 1986; Litz & Keane, 1989) avoidance is conceptualized as the primary response to intrusive thoughts of the trauma that can provide either temporary relief as the traumatic material is gradually integrated, or if exercised excessively, can impede emotional processing of the traumatic memories. It is held that cognitive or behavioral avoidance strategies can impair the opportunity for traumatic material to be engaged and resolved, and therefore it is theorized that avoidance is a primary predictor of chronic PTSD. Although avoidance behavior in PTSD has been reported to be predictive of ongoing disturbance (Bryant & Harvey, 1995c; Schwartz & Kowalski, 1992; Solomon, Mikulincer, & Flum, 1988), the relationship between avoidance and intrusive thoughts appears to be complex. Two recent prospective studies employed path analyses to clarify the relationship of intrusions and avoidance (Creamer et al., 1992; McFarlane, 1992a). Both studies reported that earlier intrusive symptoms, but not avoidance, predicted disturbance at 1 year. Further, although the relationship between intrusions and avoidance is strong soon after the trauma, it weakens as time elapses (Creamer et al., 1992). The degree of independence between intrusions and avoidance when assessed some time after a trauma may indicate that factors other than intrusions contribute to avoidance behaviour (Ehlers & Steil, 1995). In this context, it is worth noting Horowitz's (1986) earlier claim that initial avoidance may serve as a modulating defence that permits m a n a g e m e n t of adverse emotions as the individual deals with their experience. In this sense, initial avoidance may serve a beneficial function and assist resolution during the acute phase. Taken together, available data suggest that whereas persistent avoidance is associated with PTSD, the relationship between initial

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avoidance and later PTSD is not adequately understood. Further prospective study is required that identifies the interaction between initial intrusions and avoidance, and longer-term psychopathology. The ASD description of avoidance varies from the PTSD diagnosis by its more flexible definition. Whereas the PTSD diagnosis requires that the individual displays at least three specified avoidance symptoms, the ASD diagnosis does not require a specific number of avoidance symptoms. The requirement that the individual suffer " m a r k e d " avoidance is vague and lacks standard parameters. This ambiguity in definition may be particularly problematic in the context of ASD, where the individual sometimes has limited exposure to reminders of the trauma, and therefore has restricted opportunity to demonstrate avoidance. For example, the trauma patient who is hospitalized may not have the opportunity to demonstrate avoidance in a range of contexts that may precipitate avoidance behavior. It is probable that the vague definition of avoidance behaviour in the ASD diagnosis may contribute to excessive variation in diagnostic decisions. AROUSAL SYMPTOMS

The ASD diagnosis requires that marked arousal be present for at least 2 days following the trauma. Arousal symptoms include restlessness, insomnia, hypervigilence, concentration difficulties, and irritability. These symptoms are reportedly common in the acute trauma response. Insomnia is reported in 68% of plane crash survivors (Sloan, 1988), 50% of ambush victims (Feinstein, 1989), 44% of earthquake survivors (Cardena & Spiegel, 1993), and nearly all the Buffalo Creek disaster survivors (Titchener & Kapp, 1976). Concentration deficits are reported in 71% of earthquake survivors (Cardena & Spiegel, 1993) and 29% of tornado survivors (North, Smith, McCool, & Lightcap, 1989). Irritability is reported in 71% of plane crash survivors (Sloan, 1988). Elevated autonomic arousal is reported in 93% of ambush survivors (Feinstein, 1989), 36% of earthquake survivors, and 70% of plane crash survivors (Sloan, 1988). The extent to which elevated arousal in the acute trauma phase reflects psychopathology is yet to be clarified. The extent to which acute arousal predicts longer-term psychopathology needs to be investigated to validate the role of this symptom cluster in the ASD diagnosis. Weisaeth (1989) found that the persistence of anxiety and sleep disturbance after the first 2 weeks posttrauma was predictive of subsequent PTSD. Others have commented from a theoretical perspective of the potential importance of initial arousal symptoms in predicting subsequent PTSD (Shalev, 1992). There is evidence, however, that the acute arousal symptoms observed following trauma typically subside in the following weeks (Cardena & Spiegel, 1993). The role of acute arousal symptoms in predicting PTSD has received surprisingly little empirical attention. Recent commentaries that have noted the emphasis on intrusive and avoidance symptoms have led to arousal being neglected by many researchers (McFarlane, 1992b). The definition of " m a r k e d " arousal also requires further clarification because it lacks specificity. Whereas the diagnosis of PTSD requires that at least two arousal symptoms be evident, the ASD diagnosis only requires "marked" arousal. This ambiguity may further contribute to diagnostic variability. Considering the problem of comorbidity of posttraumatic conditions and the commonality of many of the arousal symptoms in numerous posttraumatic disorders, it is imperative that future research clarifies the role of arousal. Specifically, prospective studies are required that delineate

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the optimal m i n i m u m n u m b e r of arousal symptoms that provide the strongest predictive power of subsequent psychopathology.

DURATION CRITERION T h e diagnosis of ASD stipulates that the disturbance must be present for at least 2 days after the trauma, and does not persist for m o r e than 1 month. It is assumed that a diagnosis of PTSD would be suitable after this time. The m i n i m u m duration of 2 days after the trauma appears to be somewhat arbitrary in that this duration is not based on empirical findings c o n c e r n i n g n o r m a l or pathological acute trauma reactions. If the diagnosis of ASD is m e a n t to describe acute responses that are predictive of longer-term psychopathology, there is a need to demonstrate that responses that do not remit within 2 days of the trauma are m o r e predictive of psychopathology. Prospective studies are required to indicate that durations of 2, rather than 3, 4, or 5 days are the strongest predictors of later disturbance. T h e r e is evidence that marked remission and change occurs in symptomatology over time. In a recent study of 48 motor-vehicle accident survivors who satisfied PTSD diagnosis between 1 and 4 months posttrauma, half had remitted at 6 months and two thirds by 12 months after the trauma (Blanchard et al., 1996). Such remission may be even m o r e marked in the first m o n t h following a trauma. For example, it is possible that an individual may display m a r k e d ASD symptoms on the third day after a trauma, process the traumatic m e m o r i e s in an adaptive m a n n e r in the ensuing days, and no longer m e e t diagnostic criteria seven days after the event. No provision has b e e n m a d e in DSM-IV for such changes. Future formulations of ASD should include in the duration criterion information based on longitudinal investigations of symptom duration to assist in differentiating between adaptive short-term and clinical responses predictive of long-term symptomatology.

Exclusion Criteria The diagnosis of ASD is not m a d e if the disturbance is better accounted for by a medical condition or substance use. Differentiating ASD symptoms f r o m the effects of some medical conditions is particularly difficult. T h e effects of traumatic brain injury (TBI) can closely mimic a range of ASD symptoms. Arousal is frequently observed a m o n g the postconcussive symptoms following TBI (Bohnen &Jolles, 1992). Further, depersonalization, derealization, and dissociative amnesia can present similarly to reports of impaired consciousness that occur in a TBI (Grigsby & Kaye, 1993). Although there are some qualitative differences between organic and dissociative amnesia (Sivec & Lynn, 1995), the distinction between mild TBI and the dissociative symptoms often reported during trauma are difficult to disentangle. Recent reports, however, have highlighted that TBI patients can experience acute posttraumatic stress symptoms (Bryant & Harvey, 1995b, 1996). Considering the traumatic circumstances that s u r r o u n d occurrence of many TBI injuries, it is likely that m a n y of these individuals may be vulnerable to ASD development. Should a diagnosis of ASD be excluded for all TBI patients because of the potential c o n f o u n d between organic and dissociative symptoms? Should one attempt to differentiate those symptoms that may result from organic versus dissociative functions? Excluding all patients who have sustained even a mild TBI may result in false negative diagnoses in this population. Alternatively, adopting a flexible definition of dissociative symptoms in TBI patients may increase the rate of false positive diagnoses. Future research that m o r e clearly

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TABLE 1. Diagnostic Criteria for Acute Stress Disorder and Posttraumatic Stress Disorder Criteria

Acute Stress Disorder

Posttraumatic Stress Disorder

Stressor

Both: Threatening event Fear, helplessness, or horror

Both: Threatening event Fear, helplessness, or horror

Dissociation

Minimum three of.' Numbing Reduced awareness Depersonalization Derealization Amnesia

NA NA NA NA NA

Reexperiencing

Minimum one of: Recurrent images/thoughts/distress Consequent distress not prescribed Intrusive nature not prescribed

Minimum one of.' Recurrent images/thoughts/distress Consequent distress prescribed Intrusive nature prescribed

Avoidance

"Marked avoidance of: Thoughts, feelings, or places

Minimum three of: Avoid thoughts/conversations Avoid people/places Amnesia Diminished interest Estrangement from others Restricted affect Sense of shortened fllture

Arousal

"Marked arousal, including: Minimum two of: Restlessness, insomnia, irritability, Insomnia hypervigilance, and concentration difficulties Concentration deficits Hypervigilence Elevated startle response

Duration

At least 2 days and less than 1 month posttrauma Dissociative symptoms may be present only during trauma

At least 1 month posttrauma

Impairment

Impairs functioning

Impairs functioning

delineates the distinction between dissociative a n d postconcussive s y m p t o m s may p e r m i t a m o r e accurate diagnosis o f acute stress reactions in TBI patients.

COMPARABILITY OF ASD A N D PTSD It is a p p a r e n t that there are n u m e r o u s inconsistencies between the diagnostic criteria for ASD a n d PTSD. T h e differences a n d similarities are o u t l i n e d in Table 1. A p a r t f r o m the emphasis o n dissociative s y m p t o m s in ASD, there are m o r e stringent requirem e n t s for the diagnosis o f the intrusive, avoidance, a n d arousal s y m p t o m s in the diagnosis o f PTSD. Accordingly, it is possible for an individual to satisfy criteria for

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ASD, and to not satisfy PTSD diagnostic criteria after 1 m o n t h has transpired even if the symptomatology has remained unchanged. For example, an individual may have satisfied ASD diagnosis by displaying marked avoidance and arousal symptoms but may not have m e t the PTSD criteria for multiple symptoms within each cluster. Such inconsistency could result in an individual satisfying criteria for a psychiatric disorder at 3 weeks posttrauma but not receiving a diagnosis 2 weeks later. In legal contexts, for example, this inconsistency could have significant ramifications. While there is no empirical justification for parallel criteria to be applied to both ASD and PTSD, there is also no data to justify the differential requirements for the disorders. Considering that DSM-IVstipulates that after 4 weeks a diagnosis of PTSD should be considered, it would seem reasonable that there should be m a x i m u m comparability between the diagnostic criteria to permit a consistent identification of individuals who are to be regarded as suffering from a pathological posttraumatic condition. MEASUREMENT OF ACUTE STRESS DISORDER Considering the recent d e v e l o p m e n t of the ASD diagnosis, it is not surprising that there are no established measures of this disorder. Researchers have traditionally indexed acute stress responses by employing measures that have been developed for PTSD. For example, the I m p a c t of Event Scale (Horowitz, Wilner, & Alvarez, 1979) has been employed to index intrusive and avoidance symptoms in the acute posttraumatic phase (Bryant & Harvey, 1995b, 1996; Dancu et al., 1996; Shale~, 1992). Measures of PTSD symptom severity, such as the PTSD Symptom Scale (Foa, Riggs, Dancu, & Rothbaum, 1993), have been employed to index intrusive, avoidance, and arousal symptoms (Dancu et al., 1996; Foa, Hearst-Ikeda, & Perry, 1995). Measures of PTSD are limited, however, in that they do not directly index dissociative symptoms. Many studies have focused on dissociative reactions following trauma by employing the DES (Branscombe, 1991; B r e m n e r et al., 1992; Dancu et al., 1996; O r r et al., 1990). This scale was developed to measure pathological dissociation, and indexes identity, perceptual, and m e m o r y disturbances. It does not index intrusive, avoidance, or arousal symptoms of ASD. Further, critical reviews of the DES have suggested that the extent to which it indexes dissociation is influenced by respondents' perceptions of the purpose of the questionnaire (Silva & Kirsch, 1992). The Peritraumatic Dissociation Experiences Questionnaire (Marmar et al., 1994) was developed to specifically index dissociative responses during and following a trauma. Accordingly, it focuses on depersonalization, derealization, and amnesia. Taken together, measures that index PTSD or dissociative symptomatology do not encompass the full range of ASD symptoms, hrhereas each of these measures has utility in indexing aspects of the acute stress response, they cannot be recognized as indices of ASD. Two measures have recently been proposed to measure acute stress responses. The Stanford Acute Stress Reaction Questionnaire (SASRC; Cardena, Classen, & Spiegel, 1991) is a 73-item inventory that indexes dissociative and anxiety symptoms that can occur during and immediately following a trauma. The questionnaire includes the symptoms that are described in the ASD diagnosis. The SASRC was not developed on the basis of ASD diagnosis, however, and there is currently no available data that indicates its utility in identifying those who satist~¢ ASD diagnosis. The Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D; Steinberg, 1993) has been offered as a structured interview for ASD. Although this interview encompasses many aspects of dissociative pathology, it provides scant measures of intrusive, avoid-

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ance, and arousal symptomatology. More importantly, there are no data c o n c e r n i n g the utility of the SCID-D with ASD populations. In summary, there are currently no standardized measures of ASD symptomatology. Whereas there are numerous structured interviews and serf-report inventories of FFSD, investigating ASD relies largely on unstructured clinical interviews. The current poor understanding of ASD may be attributed, in part, to a lack of standardized measures that are employed in the acute trauma phase. Reports of acute trauma symptoms include variable rates of incidence. For example, the rate of dissociative amnesia is reported to occur in between 5% (Torrie, 1944) and 61% (Madakasira & O'Brien, 1987) of cases in the acute trauma phase. Although such variance in incidence may be a product of differences in trauma severity or trauma population, it is also possible that differences in assessment methodology may result in discrepant patterns. Development of structured interviews and serf-report inventories that have sound psychometric properties are essential if rigorous research into ASD is to proceed. TRAUMA POPULATIONS T h e utility of ASD needs to be d e t e r m i n e d in the context of a range of trauma populations. It is possible that the variability of r e p o r t e d findings may be attributed, in part, to differential responses of distinct trauma populations. For example, there is evidence that dissociative responses are m o r e frequently observed in p r o l o n g e d and severe traumas ( H e r m a n , Perry, & van der Kolk, 1989). It is possible that the role of peritraumatic dissociative responses in m o r e severe traumas, such as p r o l o n g e d rape, may be different f r o m the role of dissociative responses in less protracted or severe traumas. Generalizing from findings of one trauma population to others may be unjustified. T h e ASD criteria n e e d to be applied to a range of trauma populations to index the utility of the symptom criteria in identifying the prognostic value of those symptoms in each population. W H A T IS A PATHOLOGICAL RESPONSE? A fundamental issue that needs to be addressed in the conceptualization of ASD is the distinction between normal and pathological responses in the acute posttrauma phase. Should extreme distress be considered pathological in the wake of a traumatic experience? Should dissociative, reexperiencing, or arousal symptoms be d e e m e d abnormal? The preceding review indicates that there is convergent evidence that these responses are very c o m m o n in the period immediately following a trauma, and that they often remit in the following weeks. This pattern indicates that pathological responses should include those that persist beyond the acute phase of the trauma, and persistently cause distress and .impairment to the individual. On this basis, the criteria for ASD should be based on the extent to which symptoms can predict subsequent psychopathology. FUTURE DIRECTIONS New diagnostic categories often have teething problems. It is only when a diagnosis enters psychiatric n o m e n c l a t u r e that standard parameters exist that allow controlled investigation of the disorder. T h e diagnosis of ASD is heavily based on a theoretical perspective that involves a causal relationship between t r a u m a and dissociation, and an assumption that ASD is predictive of longer-term posttraumatic psychopathology. T h e r e is now a n e e d for controlled investigation of these assumptions to d e t e r m i n e

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t h e m o s t a p p r o p r i a t e c r i t e r i a f o r A S D d i a g n o s i s . T h e r e a r e a n u m b e r o f critical a r e a s t h a t this i n v e s t i g a t i o n s h o u l d a d d r e s s . T h e r e l a t i v e i m p o r t a n c e o f d i s s o c i a t i v e , i n t r u sive, a v o i d a n c e , a n d a r o u s a l s y m p t o m s in p r e d i c t i n g l a t e r d i s t u r b a n c e m u s t b e clarified. T h e d u r a t i o n o f e a c h s y m p t o m c l u s t e r n e e d s to b e e m p i r i c a l l y e s t a b l i s h e d in t e r m s o f its p r e d i c t i o n o f l o n g e r - t e r m p a t h o l o g y , h n p o r t a n t l y , t h e s p e c i f i c n u m b e r o f s y m p t o m s in e a c h c l u s t e r also r e q u i r e s s p e c i f i c a t i o n . T h e p r e l i m i n a r y e v i d e n c e t h a t some features of the acute response can predict longer-term psychopathology suggests t h a t t h e i n t r o d u c t i o n o f A S D is a valid a n d i m p o r t a n t d e v e l o p m e n t . T h e p r o b l e m s i n h e r e n t in t h e c u r r e n t c r i t e r i a f o r this d i a g n o s i s m a y b e a t t r i b u t e d , in p a r t , to t h e l a c k o f e m p i r i c a l r e s e a r c h t h a t p r e c e d e d this d i a g n o s i s . As r e s e a r c h c o n t i n u e s in this critical a r e a , f u t u r e r e v i s i o n s o f A S D c r i t e r i a s h o u l d b e d e t e r m i n e d by e m p i r i c a l evidence rather than theoretical propositions.

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