For the week’s topics of Anxiety and Obsessive-Compulsive Disorders and Trauma: Abuse, Neglect, and Domestic Violence, analyze the primary arguments present

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

Cognitive predictors of posttraumatic stress disorder in children: 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, UK b 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 who had experienced a road traffic accident. Children were assessed at 2 weeks, 3 months, and 6 months after the accident. Data-driven processing during the accident, negative interpretation of intrusive memories, alienation from other people, anger, rumination, thought suppression and persistent dissociation at initial assessment predicted PTSD symptom severity at 3 and 6 months. On the basis of sex and stressor severity variables, 14% of the variance of PTSD symptoms at 6 months could be explained. The accuracy of the prediction increased to 49% or 53% when the cognitive variables measured at initial assessment or 3 months, 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 children who have experienced traumatic events such as road traffic accidents (RTAs). Recent estimates suggest 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 contribute to the development and maintenance of PTSD in children.

The present study explored whether psychological variables that have been shown to predict PTSD after an RTA in adults also predict PTSD in children. In previous research with adult RTA survivors, objective indicators of trauma severity such as injury severity were poor predictors of PTSD symptoms. In contrast, the individuals’ subjective response to the event, in particular their perceived 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 of chronic 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 taken into 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 strong priming and conditioning for associated cues) to easy triggering of re-experiencing symptoms when matching cues are present. The deficit in elaboration/integration of the trauma memory is 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-driven processing (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/or its sequelae (including the initial PTSD symptoms), leading to a sense of current threat (see also 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 intended to control the perceived current threat, but maintain the problem (see also Ehlers & Steil, 1995; Steil & Ehlers, 1995). Examples include thought suppression, avoidance, rumination, and persistent 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 trauma memory 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 appraisals of the trauma and its sequelae were strongly related to PTSD severity across a range of different traumas (Dunmore, Clark, & Ehlers, 1999, 2001; Foa, Ehlers, Clark, Tolin, & Orsillo, 1999). Common negative appraisals of the trauma in PTSD include overgeneralization of danger, global negative 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 negatively by trauma survivors include the initial symptoms of PTSD, e.g. intrusive memories may be inter-

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preted as a sign of going crazy (Clohessy & Ehlers, 1999; Ehlers & Steil, 1995; Ehlers, Mayou et al., 1998; Steil & Ehlers, 2000), and the reactions of others in the aftermath of the event that may 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 staff have 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 have found that dissociation during trauma predicts subsequent PTSD (Ehlers et al., 1998; Halligan et al., 2001; Koopman, Classen, & Spiegel, 1994; Shalev, Peri, Canetti, & Schreiber, 1996; Murray et al., in press). However, dissociation can also be a more persistent response style thought to prevent a change in trauma memories. Murray et al. (in press) and Halligan et al. (2001) found that persistent dissociation was a better predictor of PTSD at 6 months after an RTA or an assault than dissociation during the trauma.

The present study was designed to explore whether the Ehlers and Clark (2000) model can be applied 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 assessment had to be brief to make the study feasible. Therefore, only a few key variables could be chosen for 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 preoccupation with 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 to reminders, 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 what can 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 symptoms such as posttraumatic stress symptoms, travel anxiety, sleep disturbance, and behavioural problems in 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, pedestrians or cyclists involved in an RTA and who were taken to the emergency department of the John

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

Radcliffe Hospital, Oxford, in July 1997–July 1998 were recruited into a prospective study. A total 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 2 weeks 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 (see Bryant 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 the parents 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. About half of the participants were teenagers, and one-fifth were under 10 years old. Most of the children had contracted soft tissue injuries (73%), 23% had bony injuries, and 4% remained uninjured; 21 had been admitted to hospital.

2.2. Measures

2.2.1. Symptoms of post-traumatic stress disorder The 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 PTSD symptoms in children (see review by McNally, 1996) were the children’s version of the Impact of 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). As items of these scales have been shown to be appropriate for children, we used them to represent the DSM-IV symptoms whenever possible. Participants were instructed to rate the symptoms on a scale from 0 ‘no’ to 3 ‘yes, often’ . The total PTSD severity score was the sum of the scores for 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 really excited or happy, or do you find it hard to cry when you are sad?” . To avoid duplication of questions, 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 “Do pictures of the accident pop into your mind” and “Do you think about the accident even if you don’ t mean to” both represented symptom B1. The maximum score for these items was used in the overall severity score. For young children, the parent attending the interview (usually the mother) 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 measures The 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

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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 ISS body 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 were included. First, we assessed whether children had no injury, soft issue injuries, or bony injuries to distinguish between forms of minor injuries. Second, we assessed whether or not children were admitted to hospital.

Two measures of subjective stressor severity were taken. First, children indicated whether or not 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 and while in hospital on a scale from 1 ‘not scared’ to 3 ‘a lot’ . The fear response score was the maximum of these two answers.

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

2.3.2. Data-driven processing of the RTA Participants 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 measures These 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 feel you 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 indirect measure of appraisals relating to unfairness, children were asked to rate “Do you get angry when you think about the accident?” .

2.3.4. Maintaining cognitive strategies These 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 kept going over the accident over and over again and whether they kept thinking again and again about why the accident happened to them. Thought suppression was measured as the response to the question “ If pictures of the accident pop into your mind do you try to stop them and push them out of your mind again?” . As a measure of persistent dissociation, three symptoms not included in the symptoms of PTSD were used, i.e. feeling in a daze, feelings of unreality, and feelings of depersonalisation. Parental attitude favouring avoidance was measured by asking the parent to rate how helpful they thought it would be to avoid reminders of the accident, for the child to push the 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 and 6 months after the accident. Sex and measures of injury severity were not significantly related to

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

Table 1 Prediction 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 0.13 Indices of objective accident severity

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

Indices of subjective accident severity Perceived threat to life/physical 0.37** 0.31** integrity Maximum fear during accident 0.28* 0.25* or in hospital

Cognitive factors assessed at 2 weeks Trauma memory measures

Data-driven processing during 0.30* 0.22(*)

accident Appraisal measures

Negative interpretation of 0.36** 0.35** intrusions Alienation 0.37** 0.41*** Anger 0.30* 0.30*

Maintaining cognitive strategies Rumination 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 months Appraisal measures

Negative interpretation of 0.27* intrusions Alienation 0.55*** Anger 0.41***

Maintaining cognitive strategies Rumination 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 fear during the accident and while in hospital showed small significant correlations with subsequent PTSD. As expected, the cognitive variables predicted subsequent PTSD symptoms. Correlations were small to moderate.

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

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In the first step, sex, hospital admission (as the injury measure with the highest correlation with PTSD symptoms), perceived threat to life and fear during the accident/time in hospital were entered 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 2 weeks into the equation, with the exception of data-driven processing as there were some missing data for this variable. The accuracy of the prediction increased significantly to 49% variance explained, 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 second step 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 PTSD symptom severity at 3 and 6 months after the accident. Nearly all of the cognitive variables showed significant correlations with PTSD severity.

Data-driven processing during the accident was related to subsequent PTSD symptoms at 3 months and showed a trend for a correlation at 6 months. This pattern of results replicates findings in 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 in the initial development of PTSD, and that its influence on PTSD in the long term depends on the presence 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 intrusive memories, perceived alienation from others, and anger (as an indicator of appraisals relating to unfairness) were significant predictors of PTSD at 3 and 6 months. The results replicate those found 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 with two 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 and adolescents after RTAs. Ehlers and Clark (2000) propose that these appraisals lead to a sense of current threat and prevent the trauma survivor from putting the trauma behind them. They also motivate the use of dysfunctional behaviours and cognitive strategies that maintain PTSD (see also Steil & Ehlers, 2000).

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

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

with time. It is possible that some degree of rumination is quite common in the initial weeks after a traumatic event, and that only persistent rumination strongly predicts PTSD. Similar results were 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 children and 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 the children’s PTSD severity at 6 months. It is possible that measures of parental behaviour rather than attitude would have been more predictive. It is also possible that a measure of the child’s perception of the parents’ behaviour would have been more predictive, as indicated by recent data by Steil, Gundlach et al. (2001). Alternatively, in the present sample, the influence of the parents on their children’s way of coping with the accident and the symptoms arising from it may 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 severity and 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 the subjective stressor severity, i.e. perceived threat to life/physical integrity and the children’s fear response were significant predictors. However, the cognitive predictors derived from the Ehlers and Clark (2000) model predicted PTSD severity over and above what could be predicted from subjective 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 of a 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 to measure 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. Similar to studies with adult RTA survivors, children who had contracted minor injuries were less likely to participate than children with more severe injuries. It cannot be determined whether this affected the patterns of correlations reported in the study, although it seems unlikely, given that injury severity was unrelated to PTSD. However, the correlations of the cognitive predictors and PTSD severity in the present study are likely to underestimate the true relationship as the use of single items rather than multi-item scales will have introduced some error variance due to measurement error. Future studies are warranted that use standardized questionnaires of established reliability to measure the cognitive constructs. Such questionnaires have already been developed for adult populations, and with adaptions in wording may prove to be useful in the prediction of chronic PTSD in children (see also Steil, Gundlach et al., 2001; Steil, Hempt et al., 2001).

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Acknowledgements

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

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