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Behaviour Research and Therapy 41 (2003) 1–10www.elsevier.com/locate/brat

Cognitive predictors of posttraumatic stress disorder inchildren: results of a prospective longitudinal study

A. Ehlersa,*, R.A. Mayoub, B. Bryantb

a Department of Psychology, Institute of Psychiatry, De Crespigny Park, Denmark Hill, London SE5 8AF, UKb Department of Psychiatry, University of Oxford, Oxford, UK

Accepted 30 October 2001

Abstract

The present study explored whether cognitive factors specified in the Ehlers and Clark model (Behav.Res. Ther. 38 (2000) 319) of posttraumatic stress disorder (PTSD) predict chronic PTSD in children whohad experienced a road traffic accident. Children were assessed at 2 weeks, 3 months, and 6 months afterthe accident. Data-driven processing during the accident, negative interpretation of intrusive memories,alienation from other people, anger, rumination, thought suppression and persistent dissociation at initialassessment predicted PTSD symptom severity at 3 and 6 months. On the basis of sex and stressor severityvariables, 14% of the variance of PTSD symptoms at 6 months could be explained. The accuracy of theprediction increased to 49% or 53% when the cognitive variables measured at initial assessment or 3months, respectively, were taken into account. 2003 Elsevier Science Ltd. All rights reserved.

Keywords:Posttraumatic stress disorder; Children; Cognitive predictors; Prospective study; Cognitive model

1. Introduction

There is increasing awareness that posttraumatic stress disorder (PTSD) is common in childrenwho have experienced traumatic events such as road traffic accidents (RTAs). Recent estimatessuggest that between 14 and 34% of children involved in an RTA will develop PTSD (e.g. Bryant,Mayou, Wiggs, Ehlers, & Stores, 2001; Canterbury & Yule, 1997; Di Gallo, Barton, & Parry-Jones, 1997; Ellis, Stores, & Mayou, 1998; Mirza, Bhadrinath, Goodyear, & Gilmore, 1998; Stal-

* Corresponding author. Tel.:+44-20-7848-5033; fax:+44-20-7848-0591.E-mail address:[email protected] (A. Ehlers).

0005-7967/03/$ - see front matter 2003 Elsevier Science Ltd. All rights reserved.PII: S0005-7967(01)00126-7

2 A. Ehlers et al. / Behaviour Research and Therapy 41 (2003) 1–10

lard, Velleman, & Baldwin, 1998). Very little is known, however, about factors that contributeto the development and maintenance of PTSD in children.

The present study explored whether psychological variables that have been shown to predictPTSD after an RTA in adults also predict PTSD in children. In previous research with adult RTAsurvivors, objective indicators of trauma severity such as injury severity were poor predictors ofPTSD symptoms. In contrast, the individuals’ subjective response to the event, in particular theirperceived threat to life, was consistently found to be a significant predictor (e.g. Blanchard et al.,1995; Ehlers, Mayou, & Bryant, 1998; Pynoos et al., 1987; see also review by March, 1993).Nevertheless, subjective stressor severity only explained a small proportion of the variance ofchronic PTSD symptoms. The accuracy of the prediction could be substantially improved if main-taining psychological factors derived from Ehlers and Clark’s (2000) model of PTSD were takeninto account (Ehlers, Mayou et al., 1998; Mayou, Ehlers, & Bryant, in press).

The Ehlers and Clark (2000) model highlights three factors thought to determine the develop-ment and maintenance of PTSD.

1. Trauma memory deficits. The memory for the traumatic event is poorly elaborated and inad-equately integrated with other autobiographical information. This leads (together with strongpriming and conditioning for associated cues) to easy triggering of re-experiencing symptomswhen matching cues are present. The deficit in elaboration/integration of the trauma memoryis due to (a) incomplete cognitive processing of the event while it is happening, and (b) cogni-tive avoidance after the event which prevents a change in memory. Ehlers and Clark (2000)specified three overlapping indicators of incomplete processing during the event, data-drivenprocessing (e.g. processing the sensory characteristics of the situation rather than its meaning),lack of self-referent processing, and dissociation.

2. Appraisals. The individual makes excessively negative appraisals of the traumatic event and/orits sequelae (including the initial PTSD symptoms), leading to a sense of current threat (seealso Ehlers & Steil, 1995; Steil & Ehlers, 1995).

3. Maintaining behaviours and cognitive strategies. The negative appraisals motivate the individ-ual to engage in a range of dysfunctional behaviours and cognitive strategies that are intendedto control the perceived current threat, but maintain the problem (see also Ehlers & Steil,1995; Steil & Ehlers, 1995). Examples include thought suppression, avoidance, rumination, andpersistent dissociation.

Evidence for the role of each of these three factors has been accumulated in a series of cross-sectional and prospective longitudinal studies of adult trauma survivors. First, indicators of traumamemory deficits and incomplete processing during trauma (data-driven processing, lack of self-referent processing and dissociation) predicted PTSD in adult RTA and assault survivors (Murray,Ehlers, & Mayou, in press; Halligan, Michael, Clark, & Ehlers, 2001). Second, negative appraisalsof the trauma and its sequelae were strongly related to PTSD severity across a range of differenttraumas (Dunmore, Clark, & Ehlers, 1999, 2001; Foa, Ehlers, Clark, Tolin, & Orsillo, 1999).Common negative appraisals of the trauma in PTSD include overgeneralization of danger, globalnegative thoughts about the self, preoccupation with unfairness and self-blame (Foa et al., 1999;Foa, Riggs, Massier, & Yarczower, 1995). Trauma sequelae that are often interpreted negativelyby trauma survivors include the initial symptoms of PTSD, e.g. intrusive memories may be inter-

3A. Ehlers et al. / Behaviour Research and Therapy 41 (2003) 1–10

preted as a sign of going crazy (Clohessy & Ehlers, 1999; Ehlers & Steil, 1995; Ehlers, Mayouet al., 1998; Steil & Ehlers, 2000), and the reactions of others in the aftermath of the event thatmay be interpreted as signs of alienation (Dunmore et al., 1999, 2001; Ehlers, Clark et al., 1998;Ehlers, Maercker, & Boos, 2000). Third, several studies of RTA survivors and ambulance staffhave supported the maintaining role of rumination and thought suppression (Clohessy & Ehlers,1999; Ehlers, Mayou et al., 1998; Murray et al., in press; Steil & Ehlers, 2000).

Dissociation has received special attention in many studies. It represents an indicator of incom-plete processing during trauma and is thus thought to lead to problematic trauma memories (e.g.Foa & Hearst-Ikeda, 1996; Spiegel & Cardena, 1990). Indeed, several prospective studies havefound that dissociation during trauma predicts subsequent PTSD (Ehlers et al., 1998; Halligan etal., 2001; Koopman, Classen, & Spiegel, 1994; Shalev, Peri, Canetti, & Schreiber, 1996; Murrayet al., in press). However, dissociation can also be a more persistent response style thought toprevent a change in trauma memories. Murray et al. (in press) and Halligan et al. (2001) foundthat persistent dissociation was a better predictor of PTSD at 6 months after an RTA or an assaultthan dissociation during the trauma.

The present study was designed to explore whether the Ehlers and Clark (2000) model can beapplied to children and adolescents. A prospective longitudinal study assessed children and ado-lescents who had been involved in an RTA at 2 weeks, 3 months, and 6 months. The assessmenthad to be brief to make the study feasible. Therefore, only a few key variables could be chosenfor the investigation:

1. Data-driven processing during the accident, as one of the indicators of incomplete processing.2. Appraisal measures that are thought to lead to a sense of current threat: negative appraisals of

intrusive memories, alienation from other people, and anger as a measure of preoccupationwith unfairness.

3. Dysfunctional cognitive strategies hypothesized to maintain PTSD: rumination, thought sup-pression, persistent dissociation, and, as children often do not have control over exposure toreminders, their parents’ attitude favouring avoidance strategies to deal with the event.

The study investigated whether these variables predict PTSD severity in children and ado-lescents at 3 and 6 months after an RTA, and whether they predict PTSD over and above whatcan be predicted from measures of objective and subjective stressor severity.

2. Method

The study was part of an investigation into the prevalence of children’s psychological symptomssuch as posttraumatic stress symptoms, travel anxiety, sleep disturbance, and behavioural problemsin the aftermath of an RTA. The prevalence data are presented in Bryant et al. (2001).

2.1. Participants

Children resident in Oxfordshire, UK, and aged 5–16 years who were passengers, pedestriansor cyclists involved in an RTA and who were taken to the emergency department of the John


Radcliffe Hospital, Oxford, in July 1997–July 1998 were recruited into a prospective study. Atotal of 150 children from 137 families were invited to take part in the study. Of these, 86 children(58%) from 80 families agreed to participate. For the 3 and 6 months assessments, data from 81(94%) and 82 (95%) of the children who participated in initial assessment were available. At 2weeks after the accident, 15% of the children met diagnostic criteria for acute stress disorder,and at 3 and 6 months, 25 and 18% of the children met criteria for PTSD, respectively (seeBryant et al., 2001, for a full description).

Non-participation was not related to the age or sex of the child, nor to the type of accident.Those with less severe injury were less likely to take part. Telephone conversations with theparents who declined participation suggested that the proportion of acute stress disorder in non-participants was comparable to that of the participants (see Bryant et al., 2001).

Fifty-five per cent of the participants were boys. Mean age was 12.3 years, SD 2.86. Abouthalf of the participants were teenagers, and one-fifth were under 10 years old. Most of the childrenhad contracted soft tissue injuries (73%), 23% had bony injuries, and 4% remained uninjured; 21had been admitted to hospital.

2.2. Measures

2.2.1. Symptoms of post-traumatic stress disorderThe dependent variable was the severity of PTSD symptoms as defined by DSM-IV (American

Psychiatric Association, 1994). When the study was planned, the best validated measures of PTSDsymptoms in children (see review by McNally, 1996) were the children’s version of the Impactof Event Scale (IES, Horowitz et al., 1979; children’s version by Yule and colleagues, e.g. Yule &Williams, 1990) and the Child Post-traumatic Stress Reaction Index (RI, Pynoos et al., 1987). Asitems of these scales have been shown to be appropriate for children, we used them to representthe DSM-IV symptoms whenever possible. Participants were instructed to rate the symptoms ona scale from 0 ‘no’ to 3 ‘yes, often’ . The total PTSD severity score was the sum of the scoresfor the 17 DSM-IV symptoms. If none of the IES or RI items measured a DSM-IV symptom,the authors constructed a new item; for example, symptom C6 was assessed with the questions:“ Is it difficult for you to have strong feelings? For example, do you find it hard to get reallyexcited or happy, or do you find it hard to cry when you are sad?” . To avoid duplication ofquestions, sleep disturbance was scored from the Sleep Behavior Questionnaire (Simonds & Par-raga, 1982). Some DSM-IV items were represented by two items, for example the IES items “Dopictures of the accident pop into your mind” and “Do you think about the accident even if youdon’ t mean to” both represented symptom B1. The maximum score for these items was used inthe overall severity score. For young children, the parent attending the interview (usually themother) complemented the child’s answers to the items and also provided information on symp-toms of repetitive play and reenactment.

2.3. Predictor variables

2.3.1. Stressor severity measuresThe Injury Severity Score (ISS) of the Abbreviated Injury Scale (AIS, American Association

for Automotive Medicine, 1985) assessed injury severity. Information was taken from the hospital


case notes. On the AIS, each injury is coded on a six-point scale from 1 ‘minor’ to 6 ‘maximum’ .The ISS is the sum of the squares of the highest AIS score in each of the three most injured ISSbody regions (head or neck, face, chest, abdominal, extremities). In addition, for comparability,two measures of injury severity as used in our previous study of adult survivors of RTAs wereincluded. First, we assessed whether children had no injury, soft issue injuries, or bony injuriesto distinguish between forms of minor injuries. Second, we assessed whether or not children wereadmitted to hospital.

Two measures of subjective stressor severity were taken. First, children indicated whether ornot they thought they were going to get hurt or die (perceived threat to life/physical integrity).Second, they indicated the extent to which they felt scared/frightened during the accident andwhile in hospital on a scale from 1 ‘not scared’ to 3 ‘a lot’ . The fear response score was themaximum of these two answers.

As presented elsewhere, characteristics of the accident and the children’s age and previouspsychological problems were not related to PTSD (Bryant et al., 2001).

2.3.2. Data-driven processing of the RTAParticipants indicated the extent to which they were muddled/confused during the accident on

a scale from 1 ‘not muddled’ to 3 ‘a lot’ .

2.3.3. Appraisal measuresThese measures were rated on a scale from 0 ‘no’ to 3 ‘yes, often’ . Negative interpretation of

intrusive memories was measured as the response to the question “Do you ever think that some-thing is wrong with you because you cannot forget the accident, for example, do you ever feelyou are going mad?” . Alienation from other people was measured as the response to the question“Do you feel like other people really don’ t understand what you went through?” . As an indirectmeasure of appraisals relating to unfairness, children were asked to rate “Do you get angry whenyou think about the accident?” .

2.3.4. Maintaining cognitive strategiesThese measures were rated on a scale from 0 ‘no’ to 3 ‘yes, often’ . As in Ehlers, Mayou et

al. (1998), rumination was scored as the mean of two items. Participants rated whether they keptgoing over the accident over and over again and whether they kept thinking again and again aboutwhy the accident happened to them. Thought suppression was measured as the response to thequestion “ If pictures of the accident pop into your mind do you try to stop them and push themout of your mind again?” . As a measure of persistent dissociation, three symptoms not includedin the symptoms of PTSD were used, i.e. feeling in a daze, feelings of unreality, and feelings ofdepersonalisation. Parental attitude favouring avoidance was measured by asking the parent torate how helpful they thought it would be to avoid reminders of the accident, for the child to pushthe memories of the accident out of his/her mind, and to act as if the accident had not happened.

3. Results

Table 1 shows the correlations of the predictor variables and PTSD symptom severity at 3 and6 months after the accident. Sex and measures of injury severity were not significantly related to


Table 1Prediction of children’s PTSD symptom severity at 3 and 6 months after a motor vehicle accident

Predictor PTSD severity

3 months 6 months

Female gender �0.01 0.13Indices of objective accident severity

Type of injury 0.07 0.00ISS score 0.01 0.12Admission to hospital 0.03 0.15

Indices of subjective accident severityPerceived threat to life/physical 0.37** 0.31**integrityMaximum fear during accident 0.28* 0.25*or in hospital

Cognitive factors assessed at 2 weeksTrauma memory measures

Data-driven processing during 0.30* 0.22(*)

accidentAppraisal measures

Negative interpretation of 0.36** 0.35**intrusionsAlienation 0.37** 0.41***Anger 0.30* 0.30*

Maintaining cognitive strategiesRumination 0.31* 0.22(*)

Thought suppression 0.29* 0.26*Persistent dissociation 0.51*** 0.42***Parental avoidant attitude 0.02 0.21(*)

Cognitive factors assessed at 3 monthsAppraisal measures

Negative interpretation of 0.27*intrusionsAlienation 0.55***Anger 0.41***

Maintaining cognitive strategiesRumination 0.55***Thought suppression 0.35**Persistent dissociation 0.61***

(*)p�0.10, *p�0.05, **p�0.01, ***p�0.00.

PTSD symptoms. The children’s perceived threat to life/physical integrity and their degree of fearduring the accident and while in hospital showed small significant correlations with subsequentPTSD. As expected, the cognitive variables predicted subsequent PTSD symptoms. Correlationswere small to moderate.

Hierarchical multiple regression analyses tested whether the cognitive factors predict PTSDsymptom severity over and above what can be predicted on the basis of sex and stressor severity.


In the first step, sex, hospital admission (as the injury measure with the highest correlation withPTSD symptoms), perceived threat to life and fear during the accident/time in hospital wereentered into the regression function. These variables predicted 14% of the variance, R2=0.136,F(4,57)=2.234, p=0.077. In the second step, we entered the cognitive predictors measured at 2weeks into the equation, with the exception of data-driven processing as there were some missingdata for this variable. The accuracy of the prediction increased significantly to 49% varianceexplained, R2 change=0.356, F change (7,50)=4.993, p=0.001, R2=0.491, F (11,50)=4.388,p�0.001.

The analysis was repeated using the cognitive variables measured at 3 months in the secondstep of the hierarchical regression. Again, the cognitive variables significantly improved the pre-diction of PTSD severity at 6 months, and together with sex and stressor severity explained 53%of the variance, R2 change=0.385, F change (5,51)=8.441, p�0.001, R2=0.534, F (9,51)=6.501,p�0.001.

4. Discussion

4.1. Do the cognitive variables derived from Ehlers and Clark’s model predict PTSD?

The results support the role of cognitive predictors of chronic PTSD in children. Our prospec-tive longitudinal study showed that cognitive factors measured soon after an RTA predict PTSDsymptom severity at 3 and 6 months after the accident. Nearly all of the cognitive variablesshowed significant correlations with PTSD severity.

Data-driven processing during the accident was related to subsequent PTSD symptoms at 3months and showed a trend for a correlation at 6 months. This pattern of results replicates findingsin adult survivors of trauma (Halligan et al., 2001) and is in line with the hypothesis that data-driven processing (like other indicators of incomplete processing) during trauma is involved inthe initial development of PTSD, and that its influence on PTSD in the long term depends on thepresence of maintaining factors.

The evidence for such maintaining factors in the present children sample was strong. All indi-cators of negative appraisals of the trauma and its sequelae, i.e. negative interpretation of intrusivememories, perceived alienation from others, and anger (as an indicator of appraisals relating tounfairness) were significant predictors of PTSD at 3 and 6 months. The results replicate thosefound with adult survivors of a range of traumas (Clohessy & Ehlers, 1999; Dunmore et al., 1999,2001; Ehlers, Mayou et al., 1998; Ehlers et al., 2000; Steil & Ehlers, 2000), and are in line withtwo recent studies by Steil, Hempt, & Deffke, 2001) who found that negative appraisals of intrus-ive memories and the trauma correlated highly with PTSD symptom severity in children andadolescents after RTAs. Ehlers and Clark (2000) propose that these appraisals lead to a sense ofcurrent threat and prevent the trauma survivor from putting the trauma behind them. They alsomotivate the use of dysfunctional behaviours and cognitive strategies that maintain PTSD (seealso Steil & Ehlers, 2000).

As expected, such dysfunctional cognitive strategies were also correlated with subsequent PTSDseverity in the children sample, i.e. rumination, suppression of intrusive memories, and persistentdissociation. For rumination, the relationship with subsequent PTSD appeared to become stronger


with time. It is possible that some degree of rumination is quite common in the initial weeksafter a traumatic event, and that only persistent rumination strongly predicts PTSD. Similar resultswere obtained in adults by Murray et al. (in press). The results for suppression of intrusive memor-ies parallel those of Steil and colleagues in a cross-sectional and a prospective study of childrenand adolescents after RTAs (Steil, Gundlach et al., 2001; Steil, Hempt et al., 2001).

Parental attitude favouring avoidance strategies only showed a trend for a correlation with thechildren’s PTSD severity at 6 months. It is possible that measures of parental behaviour ratherthan attitude would have been more predictive. It is also possible that a measure of the child’sperception of the parents’ behaviour would have been more predictive, as indicated by recentdata by Steil, Gundlach et al. (2001). Alternatively, in the present sample, the influence of theparents on their children’s way of coping with the accident and the symptoms arising from itmay have been limited, especially since about 50% of the sample comprised teenagers.

4.2. Do the cognitive variables predict PTSD over and above other predictors?

The power of the cognitive variables in predicting subsequent PTSD symptoms has to be inter-preted against a background of other variables that are potential predictors. Sex, injury severityand other accident and sample characteristics did not significantly predict PTSD symptom severity(Bryant et al., 2001). In line with other studies (reviewed by March, 1993), indicators of thesubjective stressor severity, i.e. perceived threat to life/physical integrity and the children’s fearresponse were significant predictors. However, the cognitive predictors derived from the Ehlersand Clark (2000) model predicted PTSD severity over and above what could be predicted fromsubjective stressor severity, increasing the accuracy of the prediction from 14% to about 50%explained variance.

4.3. Limitations and conclusions

The present study had several strengths and weaknesses. Among the strengths was the use ofa prospective longitudinal design and the recruitment from a consecutive sample of patients.Among the weaknesses was a modest participation rate and the use of few or single items tomeasure the constructs. The analysis of responses of parents who declined participation suggested,however, that the remaining sample was not biased towards a higher or lower PTSD rate. Similarto studies with adult RTA survivors, children who had contracted minor injuries were less likelyto participate than children with more severe injuries. It cannot be determined whether this affectedthe patterns of correlations reported in the study, although it seems unlikely, given that injuryseverity was unrelated to PTSD. However, the correlations of the cognitive predictors and PTSDseverity in the present study are likely to underestimate the true relationship as the use of singleitems rather than multi-item scales will have introduced some error variance due to measurementerror. Future studies are warranted that use standardized questionnaires of established reliabilityto measure the cognitive constructs. Such questionnaires have already been developed for adultpopulations, and with adaptions in wording may prove to be useful in the prediction of chronicPTSD in children (see also Steil, Gundlach et al., 2001; Steil, Hempt et al., 2001).


Acknowledgements

The study was funded by a grant from the Wellcome Trust. Anke Ehlers is a Wellcome PrincipalResearch Fellow. We thank Luci Wiggs and Ann Day for their help with the study. We aregrateful for the collaboration of the John Radcliffe Accident and Emergency Services. We wouldalso like to thank the parents and children who participated in the study.

References

American Association for Automotive Medicine (1985). The abbreviated injury scale. Des Plaines, IL: AmericanAssociation for Automotive Medicine.

American Psychiatric Association (1994). Diagnostic and statistical manual of mental disorders (DSM-IV) (4th ed.).Washington, DC: APA.

Blanchard, E. B., Hickling, E. J., Mitnick, N., Taylor, A. E., Loos, W., & Buckley, T. C. (1995). The impact of severityof injury and perception of life threat in the development of posttraumatic stress disorder after motor vehicle acci-dents. Behaviour Research and Therapy, 33, 529–534.

Bryant, B., Mayou, R.A., Wiggs, L., Ehlers, A., & Stores, G. (2001). Psychological consequences of road trafficaccidents in children and their mothers. Submitted for publication.

Canterbury, R., & Yule, W. (1997). The effects in children of road traffic accidents. In M. Mitchell (Ed.), The aftermathof road traffic accidents. London: Routledge.

Clohessy, S., & Ehlers, A. (1999). PTSD symptoms, response to intrusive memories, and coping in ambulance serviceworkers. British Journal of Clinical Psychology, 38, 251–265.

Di Gallo, A., Barton, J., & Parry-Jones (1997). Road traffic accidents: early psychological consequences in childrenand adolescents. British Journal of Psychiatry 170, 358–362.

Dunmore, E., Clark, D. M., & Ehlers, A. (1999). Cognitive factors involved in the onset and maintenance of PTSD.Behaviour Research and Therapy, 37, 809–829.

Dunmore, E., Clark, D. M., & Ehlers, A. (2001). A prospective study of the role of cognitive factors in persistentposttraumatic stress disorder after physical or sexual assault. Behaviour Research and Therapy, 39, 1063–1984.

Ehlers, A., & Clark, D. M. (2000). A cognitive model of posttraumatic stress disorder. Behaviour Research and Therapy,38, 319–345.

Ehlers, A., Clark, D. M., Dunmore, E. B., Jaycox, L., Meadows, E., & Foa, E. B. (1998). Predicting response toexposure in PTSD: the role of mental defeat and alienation. Journal of Traumatic Stress, 11, 457–471.

Ehlers, A., Maercker, A., & Boos, A. (2000). PTSD following political imprisonment: the role of mental defeat, alien-ation, and permanent change. Journal of Abnormal Psychology, 109, 45–55.

Ehlers, A., Mayou, R. A., & Bryant, B. (1998). Psychological predictors of chronic PTSD after motor vehicle accidents.Journal of Abnormal Psychology, 107, 508–519.

Ehlers, A., & Steil, R. (1995). Maintenance of intrusive memories in posttraumatic stress disorder: a cognitive approach.Behavioural and Cognitive Psychotherapy, 23, 217–249.

Ellis, A., Stores, G., & Mayou, R. (1998). Psychological consequences of road traffic accidents in children. EuropeanChild and Adolescent Psychiatry, 7, 61–68.

Foa, E. B., Ehlers, A., Clark, D. M., Tolin, D., & Orsillo, S. (1999). The Post-traumatic Cognitions Inventory (PTCI).Development and validation. Psychological Assessment, 11, 303–314.

Foa, E. B., & Hearst-Ikeda, D. (1996). Emotional dissociation in response to trauma: an information-processingapproach. In L. K. Michelson, & W. J. Ray (Eds.), Handbook of dissociation: theoretical, empirical, and clinicalperspectives. New York: Plenum Press.

Foa, E. B., Riggs, D. S., Massier, E. D., & Yarczower, M. (1995). The impact of fear activation and anger on theefficacy of exposure treatment for PTSD. Behavior Therapy, 26, 487–500.

Halligan, S.L., Michael., T, Clark, D.M., & Ehlers, A. (2001). Posttraumatic stress disorder following assault: the roleof cognitive processing, trauma memory, and appraisals. Submitted for publication.


Horowitz, M., Wilner, N., & Alvarez, W. (1979). Impact of event scale: a measure of subjective stress. PsychosomaticMedicine, 41, 209–218.

Koopman, C., Classen, C., & Spiegel, D. (1994). Predictors of posttraumatic stress symptoms among survivors of theOakland/Berkeley Calif., firestorm. American Journal of Psychiatry, 151, 888–894.

March, J. S. (1993). What constitutes a stressor? The ‘A’ criterion issue. In R. T. Davidson, & E. B. Foa (Eds.),Posttraumatic stress disorder and beyond (pp. 37–56). Washington, DC: American Psychiatric Press.

Mayou, R.A., Ehlers, A., & Bryant, B. (in press). Posttraumatic stress disorder after motor vehicle accidents: 3-yearfollow-up of a prospective longitudinal study. Behaviour Research and Therapy.

McNally, R. J. (1996). Assessment of posttraumatic stress disorder in children and adolescents. Journal of SchoolPsychology, 34, 147–161.

Mirza, K. A. H., Bhadrinath, B. R., Goodyear, I. M., & Gilmour, C. (1998). Post-traumatic stress disorder in childrenand adolescents following road traffic accidents. British Journal of Psychiatry, 172, 443–447.

Murray, J., Ehlers, A., & Mayou, R.A. (in press). Dissociation and posttraumatic stress disorder: two prospective studiesof motor vehicle accident survivors. British Journal of Psychiatry.

Pynoos, R. S., Frederick, C., Nader, K., Arroyo, W., Steinberg, A., Eth, S., Nunez, F., & Fairbanks, L. (1987). Lifethreat and posttraumatic stress in school-age children. Archives of General Psychiatry, 44, 1057–1063.

Shalev, A., Peri, T., Canetti, L., & Schreiber, S. (1996). Predictors of PTSD and injured trauma survivors: a prospectivestudy. American Journal of Psychiatry, 153, 219–225.

Simonds, J. F., & Parraga, H. (1982). Prevalence of sleep disorders and sleep behaviors in children and adolescents.Journal of the American Academy of Child Psychiatry, 21, 383–388.

Spiegel, D., & Cardena, E. (1990). Dissociative mechanisms in posttraumatic stress disorder. In M. E. Wolf, & A. D.Mosnaim (Eds.), Posttraumatic stress disorder: etiology, phenomenology, and treatment. Washington: AmericanPsychiatric Press.

Stallard, P., Velleman, R., & Baldwin, S. (1998). Prospective study of post-traumatic stress disorder in children involvedin road traffic accidents. British Medical Journal, 317, 1619–1623.

Steil, R., & Ehlers, A. (2000). Dysfunctional meaning of posttraumatic intrusions in chronic PTSD. Behaviour Researchand Therapy, 38, 537–558.

Steil, R., Gundlach, P., Muller, S., & Schier, F. (2001). Posttraumatic stress disorder in child and adolescent survivorsof motor vehicle accidents—is a cognitive model applicable to children and adolescents? Submitted for publication.

Steil, R., Hempt, A., & Deffke, I. (2001). PTSD in children and adolescents. Paper at the World Conference of theAssociation for the Advancement of Behavior Therapy, Vancouver, Canada, 21.7.2001.

Yule, W., & Williams, R. M. (1990). Post-traumatic stress reactions in children. Journal of Traumatic Stress, 3,279–295.

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