Individuals who have been exposed to traumatic events

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1 ORIGINAL ARTICLES Schizotypy: A Vulnerability Factor for Traumatic Intrusions Emily A. Holmes, DClinPsy,* and Craig Steel, PhD Abstract: Intrusive mental experiences occur within posttraumatic stress disorder (PTSD) and some psychotic disorders. Similarities in the phenomenology and content in the intrusions of both disorders have been noted. Currently there is little understanding of any common etiology in terms of information-processing styles. This study investigated predictors of analogue posttraumatic intrusive cognitions within a nonclinical sample, including schizotypy, dissociation, and trauma history. Forty-two participants watched a trauma video and recorded trauma-related intrusions occurring for 1 week. More reported intrusive experiences were associated with high positive symptom schizotypy. Our findings are discussed in relation to the possible role of trauma-related intrusions within psychotic disorders. (J Nerv Ment Dis 2004;192: 28 34) Individuals who have been exposed to traumatic events frequently report experiencing trauma-related intrusive images. These images are often distressing and if maintained may be associated with a clinical diagnosis of posttraumatic stress disorder (PTSD; American Psychiatric Association, 1994). The diagnostic criteria for PTSD include exposure to an event involving actual or threatened death or serious injury or threat to the physical integrity of self or others in which the person experienced intense fear, helplessness, or horror (American Psychiatric Association, 1994). The response to the event is characterized by recurrent and intrusive distressing recollections of the event and avoidance of stimuli associated with the trauma and physical hyperarousal. Thus, a hallmark of PTSD is intrusive memories of particular moments of a trauma, which can be experienced as happening in *MRC Cognition and Brain Sciences Unit, Cambridge, United Kingdom; Department of Psychiatry and Behavioural Sciences, University College London, Holborn Union Building, Archway Campus, London, N19 5LW, United Kingdom. This work was supported in part by Camden and Islington Mental Health and Social Care Trust, and Wellcome Grant Send reprint requests to Dr. Steel. Copyright 2004 by Lippincott Williams & Wilkins ISSN: /04/ DOI: /01.nmd b the present, are associated with high affect, and contain a sense of current threat (Brewin and Holmes, 2003; Ehlers and Clark, 2000; Gray et al., 2001). It is the occurrence of intrusive trauma-related memories that form the focus of the current study. Dissociation is characterized by a sense of derealization, depersonalization, explicit memory loss, and emotional numbing (Foa and Hearst-Ikeda, 1996) and is considered to be a defensive response that may serve a functional role during intense distress (van der Kolk et al., 1996). However, dissociation during trauma that is, peritraumatic dissociation (Shalev et al., 1996) and high trait dissociation (Murray et al., 2002) have been associated with an increased level of PTSD symptoms. Traumatic and other stressful life events may not only act as a trigger for PTSD but also have been argued to act as a trigger for psychotic episodes within biologically vulnerable individuals (e.g., Zubin and Spring, 1997). Schizophrenia is a form of psychotic disturbance that is diagnosed on the basis of a range of symptoms including delusional beliefs, hallucinations (both auditory and visual), and thought disorder along with social withdrawal and a lack of affect (American Psychiatric Association, 1994). The concept of schizotypy is a relatively recent development in which it is argued that schizophrenic symptomatology exists in milder forms within nonpatient populations. Differing theoretical approaches have been taken towards the conceptualization of schizotypy. While some researchers suggest schizotypy to be taxonic (e.g., Lenzenweger and Moldin, 1990), the current research adopts a fully dimensional model of schizotypy (Claridge, 1997) in which psychotic personality traits are considered to be part of normal individual differences. Within this perspective, an extreme manifestation of schizotypal personality traits represents one of a range of factors that may predispose an individual to psychotic illness. These personality traits have been measured using a range of schizotypal personality questionnaires, such as the Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE; Mason et al., 1995). Unlike the scales previously developed by Chapman and colleagues (e.g., the Perceptual Abberation Scale, Chapman et al., 1978), the O-LIFE is not specifically intended to measure mild first rank symptoms of schizophrenia but is 28

2 Schizotypy and Traumatic Intrusion derived from a variety of schizotype scales and is designed to reflect a fully dimensional model of schizotypy. Support for such a model comes from reports of similarities in performance between positive symptom schizophrenic patients and individuals who score above the mean on positive symptom schizotypy scales, such as the Unusual Experiences subscale of the O-LIFE, within a range of experimental tasks (e.g., Steel et al., 1996; 2002). Within the concept of schizotypy adopted by the current study, it is argued that schizotypal personality traits can be associated with information-processing styles. Further, both occur within a continuum. Consequently, it is predicted that evidence of an information-processing style associated with high-scoring positive schizotypes would generalize to patients with psychosis and vice versa. When considering the possibility of traumatic events acting as a trigger for both PTSD and psychosis, it is of interest to note that the symptoms associated with both disorders contain some phenomenological similarities. For example, hallucinations are often experienced as involuntary intrusions associated with high affect (Nayani and David, 1996), as are the intrusions associated with PTSD. Morrison et al. (2002) report a case series of patients with delusions and/or hallucinations who also experienced symptom-related recurrent intrusive images. The content of these intrusions was also linked to traumatic events that had been experienced by the patient, e.g., being assaulted. Consistent with these observations, intrusive experiences have also been incorporated within two recent psychological accounts of psychotic symptoms (Hemsley, 1994; Morrison, 2001). Morrison (2001) argues that hallucinations and delusions may be conceptualized as the product of idiosyncratic appraisals of intrusive experiences. Further, the cultural unacceptability of these appraisals determines the psychiatric diagnosis. For example, a person may have an intrusive memory image yet interpret it as telepathy and a sign that the devil is communicating with him/her. However, Morrison s model does not address how intrusive experiences may develop before their appraisal. Hemsley (1994) places a greater emphasis on an individual s information processing style and consequently on how intrusions might arise. It is argued that both individuals suffering from acute schizophrenia and high scoring positive schizotypes exhibit a relatively weakened ability to integrate information within a temporal and spatial context (Jones et al., 1991; Steel et al., 2002), resulting in the occurrence of intrusive experiences. However, there has to date been no experimental investigation of the development of trauma-related intrusions in relation to either people diagnosed with a psychotic disorder or an analogue population categorized on the basis of a schizotypy questionnaire. Recent research has led to a growing interest in the overlap between PTSD and psychotic intrusions. A question of interest is why some traumatized individuals develop PTSD symptoms, such as clear trauma-related intrusions, while others develop hallucinations or delusional beliefs. Although a traumatic event may serve as a trigger for a range of intrusive experiences, little is known about the individual differences that may determine the phenomenology of trauma-related intrusions. Given the associated treatment implications, it would seem to be an important area in which to develop our understanding. To study trauma-related intrusions within the field of PTSD, researchers have used the stressful film paradigm. This paradigm creates an analogue trauma after which intrusions can be studied within a prospective design. Participants watch a traumatic film and then monitor the number of intrusions of the film experienced during the following week. Thus, the paradigm enables researchers to control exposure to a traumatic event meeting diagnostic criteria, while ensuring that the recorded intrusions are directly related to the content of the event. The reported intrusions have been shown to arise spontaneously and be somewhat distressing (Holmes et al., 2003 ) and possess phenomenological properties consistent with a clinical presentation of PTSD. Using such a methodology, various predictors of intrusion vulnerability have been identified. These are increased state dissociation during the film (Holmes et al., 2003 ), increased negative mood and thought suppression (Davies and Clark, 1998), increased worry after the film (Butler et al., 1997), and focusing on the sensory and perceptual aspects of the film rather than its meaning (Halligan et al., 2002). Such research has contributed to the development of cognitive models of PTSD and associated treatment interventions (Ehlers and Clark, 2000; Brewin, 2001; Brewin and Holmes, 2003). While the use of an analogue design has inherent limitations, within trauma research it enables control over the content of the traumatic event, along with the measurement of pretrauma characteristics and immediate posttrauma reactions. One advantage of using analogue studies within schizophrenia research is that it allows data to be interpreted without the contaminating effect of a generalized performance deficit normally present within a patient population (Nuechterlein, 1977). Overall, the stressful film paradigm provides a methodological window and is supported by related findings using clinical populations and real trauma exposure (e.g., Murray et al., 2002). The current study aims to employ the stressful film paradigm to explore the relationship between trauma-related intrusions and individual differences in positive schizotypy. Holmes EA, Brewin CR, Hennesy RG (2003) Trauma films, informationprocessing and intrusive memory development. Manuscript submitted for publication Lippincott Williams & Wilkins 29

3 Holmes and Steel However, given that individuals who score highly on positive symptom aspects of schizotypy also tend to score high on trait dissociation, as measured by the Dissociative Experiences Scale (DES; Merckelbach et al., 2000; Startup, 1999), the current study investigates the development of intrusions within a nonclinical sample, rated on both schizotypy and dissociation scales. On the basis of Hemsley s (1994) theoretical model, we suggest that individuals scoring high on positive schizotypy may have an information-processing style that makes them vulnerable to having intrusive mental experiences of trauma. It is therefore hypothesized that participants scoring high on the positive symptom schizotypy scale of the O-LIFE (Unusual Experiences) will report a higher number of intrusions than low scorers. Also, consistent with previous research (Holmes et al., 2003; Murray et al., 2002), it is predicted that a higher level of trait and peritraumatic dissociation will be associated with increased intrusions. A self-report measure of the number of traumatic events individuals have experienced in their lifetime will also be completed. Given that a number of variables are predicted to be associated with more frequent intrusions and that positive schizotypy and trait dissociation exhibit a high level of covariance, a multiple regression analysis will be used to determine the relative strength of prediction of these variables. METHODS Participants Forty-two student volunteers (22 female, 20 male) took part and were paid an honorary fee. Participants were recruited through advertisements on the university campus. The mean age was 23.1 years (SD 7.3, range 18 to 55). Participants described their ethnicity as White British (23), White European (7), White North American (5), Indian (3), Mixed ethnic origin (3), or Japanese (1). All were fluent in English. No participant reported receiving treatment of a mental health problem. As part of a separate study within an experimental series by Holmes et al.. (2003), participants were randomly assigned to one of four conditions in which they conducted various concurrent manual tasks while watching the video. The tasks did not interfere with their viewing ability. These conditions did not significantly differ in their effect on intrusions nor any of the measures of schizotypy, dissociation, or diary compliance. Consequently, the following results are reported without further reference to these conditions. 30 Measures Schizotypy The Oxford-Liverpool Inventory of Feelings and Experiences (O-LIFE; Mason et al., 1995) was developed from a factor analysis of different schizotypy scales, such as the Perceptual Aberration Scale (Chapman et al., 1978) and the Magical Ideation Scale (Eckbald and Chapman, 1983). Subscales include: Unusual Experiences (UnEx) assessing perceptual aberration, magical thinking, and hallucinatory experiences consistent with positive symptoms; Cognitive Disorganization (CogDis) assessing attention, concentration, decision making, purposelessness, moodiness, and social anxiety; Introvertive Anhedonia (IntAn) assessing a lack of enjoyment from social sources and other activities; Impulsive Nonconformity (ImpNon) measuring disinhibition and impulse-ridden characteristics. Trait Dissociation The revised Dissociative Experiences Scale was used (DES-II; Carlson and Putnam, 1993). Participants indicate the percentage of time they have a given experience in daily life, from 0% (never) to 100% (always). Analogue Peritraumatic Dissociation The Peritraumatic Dissociative Experiences Questionnaire (PDEQ; Marmar et al., 1997) is a measure of dissociative symptoms experienced at the time of trauma. The 10 items on this questionnaire are rated on a 5-point scale. Intrusive Images Participants recorded any spontaneously occurring intrusions related to the film over the subsequent 7 days in a formatted diary (c.f. Brewin and Saunders, 2001; Davies and Clark, 1998; Holmes et al., 2003 ). Clear verbal and written instructions were given about the nature of intrusions and how to complete the diary. As in assessing reexperiencing symptoms in PTSD, intrusions were defined as intrusive memories of the video that suddenly pop into mind spontaneously and not times when you deliberately think about it or mull it over. The total number of intrusions was calculated from the diary. At follow-up, a diary compliance rating was taken on an 11-point scale, where 0 represented total compliance (Davies and Clark, 1998). Trauma History Checklist A 12-item questionnaire, developed for the current study, required participants to endorse whether or not they had experienced or witnessed various traumatic events covered in a routine clinical assessment for PTSD. These include road traffic accidents and physical and sexual assault. This was scored by calculating the total number of traumas endorsed. Procedure Participants read information concerning the study and gave their informed consent. Participants demographic details were then obtained, followed by the administration of the Dissociative Experiences Scale (DES-II) and the trauma history checklist. A 12.5-minute video developed by Steil (1996) and used in previous studies (Brewin and Saunders, 2001; Holmes et al., 2003, Halligan et al., 2002) was 2004 Lippincott Williams & Wilkins

4 Schizotypy and Traumatic Intrusion displayed on a TV monitor. The video depicted the real aftermath of road traffic accidents. Participants were instructed to pay attention to the film without looking away, as they would be asked questions about it later. After the viewing the film they completed the peritraumatic dissociation questionnaire. Participants were then instructed in the use of the intrusion diary. The follow-up session was conducted after one week. Participants completed the diary compliance rating and the O-LIFE. Participants were debriefed and given contact details to use should they feel distressed. No participants made subsequent contact. RESULTS All 42 participants completed all questionnaires, the experimental task, and kept diaries of their intrusions during the following week. Statistical Analyses Two univariate outliers were adjusted to one unit larger than the next most extreme score in the distribution (Tabachnick and Fidell, 1996). One multivariate outlier was removed. Correlations were carried out between all measures with age, and t-tests were performed to explore any differences with relation to gender. None reached significance. As all data were of a near normal distribution, parametric tests, including Pearson correlations, were used to analyze the relationship between variables. All data were inspected for biased responding. Table 1 shows participants mean scores, standard deviations, range and reliability coefficients on the O-LIFE, trait dissociation, and peritraumatic dissociation scales. The current sample revealed adequate psychometric properties with participants scores representing almost the full range of the schizotypy continuum. TABLE 1. Means, Standard Deviations, Range and Alpha Coefficients for O-LIFE subscales, Trait Dissociation, and Peritraumatic Dissociation Scores (N 41) Mean SD Range Alpha Coeff. UnEx CogDis IntAn ImpNon DES-II PDEQ UnEx, Unusual Experiences scale; CogDis, Cognitive Disorganisation scale; IntAn, Introvertive Anhedonia scale; ImpNon, Impulsive Nonconformity scale; DES-II, Dissociative Experiences Scale; PDEQ, Peritraumatic dissociation scale. Intrusions and Diary Compliance As shown in Tables 2 and 3, diary compliance ratings did not correlate significantly with any of the O-LIFE scales, trait dissociation, peritraumatic dissociation, or trauma history. Overall, the mean number of intrusions per participant was 5.73 (SD 5.50, range 0 to 21). The Relationship Between Schizotypy, Dissocation, and Trauma History The relationships among the O-LIFE scales, trait and peritraumatic dissociation, trauma history, and diary compliance are shown in Table 2. Levels of trait dissociation, as measured by the DES-II, correlate significantly with three of the schizotypy scales (UnEx, CogDis, ImpNon), but not with the negative schizotypy scale (IntAn). DES-II scores did not correlate with trauma history self-report. Peritraumatic dissociation (PDEQ) correlated significantly with the Cognitive Disorganization schizotypy scale but no other schizotypy scale, DES-II, or trauma history. Reported trauma history correlated positively with the Unusual Experiences scale, while correlations between trauma history and measures of dissociation did not reach significance. Relationships Among Schizotypy, Dissociation, and Intrusions Measures of positive schizotypy (Unusual Experiences), negative schizotypy (Introvertive Anhedonia), trait dissociation, peritraumatic dissociation, diary compliance, and trauma history were entered into a multiple regression predicting the number of intrusions reported. Overall, the regression analysis was significant [R 0.57, F(5,35) 3.3, p 0.02]. The individual regression coefficients, along with zero-order correlations, are reported in Table 3. The Cognitive Disorganization and Impulsive Nonconformity scales have not been included within the regression analysis as they are both highly correlated with the Unusual Experiences scale (see Table 1). Consistent with the hypothesis, the Unusual Experiences scale was entered into the regression analysis as the main positive schizotypy scale. As can be seen, the Unusual Experiences scale was the only independent predictor of intrusion frequency, although trait dissociation was also significant within a zero-order correlation. Other schizotypy scales were significantly associated with more frequent intrusions but to a lesser degree than the Unusual Experiences scale (Cognitive Disorganization, r 0.38, p 0.01; Impulsive Nonconformity, r 0.32, p 0.04). As previous research has noted that some common items exist between the positive schizotypy and trait dissociation scales (Startup, 1999), a regression analysis was repeated using modified scales in which the common items were removed from both scales. An identical pattern of results was obtained Lippincott Williams & Wilkins 31

5 Holmes and Steel TABLE 2. Pearson s Correlations between O-LIFE Scores, Trait Dissociation, Peritraumatic Dissociation, Trauma History and Diary Compliance (N 41) UnEx CogDis ImpNon IntAn DES-II PDEQ Trauma History CogDis 0.66** ImpNon 0.58** 0.45** IntAn DES-II 0.57** 0.58** 0.47** 0.13 PDEQ * * Trauma History 0.33* Diary Compliance UnEx, Unusual Experiences scale; CogDis, Cognitive Disorganisation scale; ImpNon, Impulsive Nonconformity scale; IntAn, Introvertive Anhedonia scale; DES-II, Dissociative Experiences Scale; PDEQ, Peritraumatic dissociation scale. *p 0.05, **p 0.01 TABLE 3. Regression Analysis Summary Statistics for Frequency of Intrusions (N 41) Zero-order correlations Standardized regression coefficient pof standardized regression coefficient UnEx 0.50** ** IntAn DES-II 0.31* PDEQ Trauma History Diary compliance UnEx, Unusual Experiences; IntAn, Introvertive Anhedonia; DES-II, Dissociative Experiences Scale; PDEQ, Peritraumatic dissociation scale. *p 0.05: **p 0.01 DISCUSSION The current study has explored the development of analogue trauma-related intrusions within positive symptom schizotypy. The key result of this initial study is the significant relationship between high scores on the positive symptom schizotypy scale (Unusual Experiences) and more reported trauma-related intrusions. The analyses also suggested that two other O-LIFE scales had a significant relationship with intrusion frequency (Cognitive Disorganization and Impulsive Nonconformity). However, these relationships would seem to be a product of these scales covariance with the main positive symptom schizotypy scale, i.e., Unusual Experiences. The current study supports previous reports of a relationship between positive schizotypy and trait dissociation (Merklebach et al., 2000; Startup, 1999). Previous reports of state dissociation as a vulnerability factor for trauma-related intrusions were also supported. However, regression analyses 32 showed that the Unusual Experiences scale was the only independent predictor of intrusions. Thus, it is possible that previous reports of a relationship between state dissociation and intrusions may be a product of the common variance between state dissociation and positive schizotypy. However, it may also be the case that dissociation plays an intermediate role between schizotypal personality traits and trauma-related intrusion development. More personally experienced traumatic events were reported by those participants scoring high on the Unusual Experiences schizotypy scale. This trend is inconsistent with Startup (1999), who reported a stronger relationship between trauma history and trait dissociation than between trauma history and positive schizotypy. However, although the relationships among positive schizotypy, dissociation, and trauma history remains to be clarified, the current study did not find a direct link between reported trauma and vulnerability to intrusions in response to analogue trauma. While the current results indicate that individuals who exhibit a high level of unusual experiences may be vulnerable to developing frequent trauma-related intrusions, the possible psychological processes involved remain to be clarified. However, it would seem appropriate to consider the results within a wider theoretical context, specifically recent models of information processing of both PTSD and psychosis. In so doing, it would appear that models of psychosis (Hemsley, 1994) and PTSD (Brewin, 2001) refer to similar psychological processes when accounting for the development of intrusive experiences. Both models refer to the manner in which incoming perceptual information is integrated within a spatial and temporal context to develop meaningful relationships. Further, both models refer to the established role of the hippocampus as the neural basis of contextual integration. As previously stated, Hemsley (1994) suggests that both individuals suffering from acute schizophrenia and high-scoring positive schizotypes exhibit a relatively weakened ability to 2004 Lippincott Williams & Wilkins

6 Schizotypy and Traumatic Intrusion integrate information within a temporal and spatial context. The consequence of poor contextual integration is a relatively unstructured sensory input and weak temporal associations between stimuli. These leave the individual vulnerable to experiencing intrusions which originate from both current redundant information and from material contained within long-term memory. It is argued that these intrusive experiences form the basis of the positive symptoms of psychosis. With reference to PTSD theory, Brewin (2001) argues that during moments of intense stress, such as traumatic hotspots (Gray et al., 2001; 2002), there is an adaptive response in which information is processed directly via the amygdala, bypassing the normal pathway through the hippocampus and facilitating the release of stress hormones. The consequence of this shortcut is a memory of the traumatic hotspot disconnected from other peritraumatic information. This type of memory can be difficult to recall voluntarily but is vulnerable to being involuntarily triggered into consciousness by stimuli directly associated with the trauma. This encoding and triggering argument is similar to Ehlers and Clark s (2000) model of PTSD, which refers to a shift from conceptual to data-driven processing during trauma. A consequence of data-driven processing is that the trauma memory is poorly elaborated and inadequately integrated into its context in time, place, subsequent and previous information (p. 7). It would therefore seem that an important component of information processing style, which may be associated with the development of intrusive symptoms in both disorders, might be the strength of temporal context within which stored information is integrated. It may be that the relatively weakened ability of high-scoring positive schizotypes to integrate information within a temporal context results in memories being stored in a manner that leaves them vulnerable to being triggered involuntarily. Further, it may be that at times of intense stress, these individuals exhibit an even more extreme information-processing style, in which the contextual integration of incoming stimuli is further weakened. Thus, memories of traumatic hotspots for positive schizotypes may be particularly vulnerable to frequent involuntary triggering, consistent with our current data. Within this perspective, it is possible that high-scoring positive schizotypes who have experienced a large number of traumatic life events may be vulnerable to experiencing frequent and varied intrusions. The overwhelming and confusing contents of their consciousness may lead to a weakened ability to make links between trauma-related intrusions and experienced events. This would leave the individual in a highly aroused state, as they search for the meaning of their conscious experience. According to this line of enquiry, it would seem appropriate for clinicians to consider experiences of trauma when working with psychosis, even though the presenting symptoms may seem estranged from reality (Fowler, 2000). As with all analogue studies, the current results require support from data collected within a clinical situation, i.e., individuals exposed to a more severe trauma and the study of intrusions within a population diagnosed with a psychotic disorder. A limitation of the current study is the reliance on self-report of intrusions within an analogue population, although this method has been used in PTSD research. While no objective measure of intrusive experiences is currently available, participants in the current study reported a high level of diary compliance, suggesting they believed that most intrusions were recorded. The content of the intrusions described in the diary all related to the trauma film, indicating we were measuring intrusions that were specific to the film, rather than general intrusive cognitions. The current study does not report the details of intrusion content and associated triggers nor has it assessed individual differences in appraisal as highlighted by Morrison (2001). Consideration of these areas could benefit future research. Further, a number of other personality variables may be associated with intrusion development that were beyond the scope of the current study. However, while our study is only a starting point for this line of enquiry, it may form the basis of further research within this fresh perspective. CONCLUSIONS There has been much recent speculation about the similarities and differences between the intrusive experiences that occur within the diagnoses of PTSD and psychosis. The current study gives some preliminary evidence indicating that individuals scoring high on positive symptom scales and consequently exhibiting positive symptom schizotypy information processing styles may be vulnerable to experiencing more trauma-related intrusions after exposure to analogue trauma. This analogue work provides a methodological window into the topical and challenging clinical issue of understanding reactions to trauma within psychosis. ACKNOWLEDGMENTS The authors thank Kerry Young, Pasco Fearon, Warren Mansell, and Chris Brewin. Anna Saunders, Kate Seviour, and Andy Haswell provided helpful experimental assistance. The authors made equal contributions to this study. We would like to thank Anke Ehlers for the loan of the film. REFERENCES American Psychiatric Association (1994) Diagnostic and Statistical Manual of Mental Disorders (4th ed.) (DSM-IV). Washington, DC: APA. 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