The level of exposure to traumatic events within the general

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1 ORIGINAL ARTICLES Positive Schizotypy and Trauma-Related Intrusions Sarah L. Marzillier, PhD,* and Craig Steel, PhD Abstract: The current study extends previous investigation of schizotypy as a vulnerability factor for trauma-related intrusions through the use of a clinical sample. Fifty people seeking psychological interventions after experiencing a distressing or traumatic event completed measures of positive schizotypy, posttraumatic stress disorder symptomatology, peritraumatic dissociation, and mood. Individuals scoring high in positive schizotypy were vulnerable to experiencing more frequent trauma-related intrusions along with wider posttraumatic stress disorder symptomatology, including hypervigilance, avoidance, and low mood. Results are discussed within a theoretical context, suggesting that certain information processing styles associated with high schizotype individuals may account for a vulnerability to trauma-related intrusions. Key Words: Schizotypy, trauma, intrusions, PTSD. (J Nerv Ment Dis 2007;195: 60 64) The level of exposure to traumatic events within the general population may be around seventy percent (see Lee and Young, 2001, for a review). A common psychological reaction to a traumatic life event is the experience of intrusions (Durham et al., 1985). Intrusions have been defined as unwanted and uncontrollable thoughts, images, memories, and impulses that involve re-experiencing a traumatic event, and are associated with high levels of distress (Kinzie et al., 1984). Recent research has suggested that intrusions often represent traumatic hotspots, i.e. moments of the trauma when the individual felt particularly high levels of negative emotions (Holmes et al., 2005). Where intrusive experiences persist for more than 1 month posttrauma, they become diagnostic of posttraumatic stress disorder (PTSD; American Psychiatric Association, 1994). However, trauma-related intrusions have been argued to be incorporated within the symptomatology of a wide range of disorders, including psychosis (Morrison et al., 2003; Steel et al., 2005). There is increasing evidence that the prevalence of trauma is elevated in people with severe mental illness or psychosis (e.g., Mueser et al., 1998). Consequently, the *University College London, United Kingdom; and Department of Psychology, Institute of Psychiatry, London, United Kingdom. Supported in part by Camden and Islington Mental Health and Social Care Trust, and Wellcome Grant Send reprint requests to Craig Steel, PhD, Department of Psychology PO77, Institute of Psychiatry, Denmark Hill, London, SE5 8AF, United Kingdom. Copyright 2007 by Lippincott Williams & Wilkins ISSN: /07/ DOI: /01.nmd relationship between trauma and psychosis has received considerable recent attention (see Morrison et al., 2003, for a review). While trauma, as a stressful event, has long been considered a potential trigger for psychosis within certain vulnerable individuals (Zubin and Spring, 1977), recent efforts have attempted to develop a more sophisticated understanding of the role of posttraumatic symptomatology within the onset and maintenance of psychotic disorder. One such approach (Steel et al., 2005) has used the study of a nonpatient population in which individuals have been rated on their level of schizotypy. The concept of schizotypy is based upon the premise that the beliefs, feelings, and experiences associated with a diagnosis of psychotic disorder occur, to varying degrees, throughout the full continuum of the normal population (Claridge, 1997). These mild forms of psychoticlike experiences are not necessarily associated with distress, and do not necessitate any intervention. Evidence for the continuum approach to psychosis is gained from a range of experimental studies in which high scoring schizotypes perform in a similar manner to individuals diagnosed with a psychotic disorder (e.g., Baruch et al., 1988; Steel et al., 1996). Such studies categorize participants as either low or high scoring schizotypes on the basis of questionnaire measures of schizotypal personality traits within the general population, such as the Schizotypal Trait Questionnaire A (Claridge and Broks, 1984). Although intrusive experiences have been highlighted as forming the basis of some psychotic symptomatology within two recent models (Hemsley, 1993; Morrison, 2001), there has been little investigation of the direct psychological impact of traumatic events on people suffering from psychosis. This area of study would seem to necessitate analogue investigations, and recently Holmes and Steel (2004) used a stressful film paradigm in which nonpatient participants were exposed to video images of the aftermath of road traffic accidents. Individuals scoring high on a scale of positive schizotypy reported experiencing more frequent intrusions of the video material within the week after the experiment. The present study builds upon previous analogue research by investigating the relationship between positive schizotypy and the frequency of trauma-related intrusions within a clinical sample, i.e., individuals who were seeking psychological help for posttraumatic distress more than 1 month after the stressful or traumatic event. Appropriately identified individuals were asked to fill in a number of questionnaires, including measures of schizotypy and posttraumatic symptomatology (Posttraumatic Stress Diagnostic Scale, PDS; Foa, 1995). The PDS contains subscales associated with the diagnostic criteria for PTSD, and thus allows for 60

2 Schizotypy and Trauma-Related Intrusions specific analysis with re-experiencing symptoms. A measure of peritraumatic dissociation was also included as this has previously been found to be a robust predictor of PTSD symptomatology (Ozer et al., 2003). The main hypothesis was that high levels of positive schizotypy would be associated with high levels of re-experiencing symptoms subsequent to the experience of a distressing event. In line with previous research (e.g., Simon, 2002; Yen et al., 2002), analyses will also be conducted with respect to trauma type, specifically analyzing reactions to both interpersonal and noninterpersonal traumatic events. METHODS Participants Participants were recruited from the waiting lists for assessment or treatment at four specialist outpatient trauma services and one general adult psychology service. Participants were selected if they were fluent English speakers referred for psychological help after experiencing a distressing life event. Exclusion criteria were a head injury at time of the event or a current psychotic illness. Fifty of 174 people (28.7%) returned completed questionnaires. The group who completed the study did not differ on gender ( 2.08, p 0.78) or age (t 0.60, p 0.55) from the group who declined to take part. Twenty-three of the respondents were male, and 27 were female. Age ranged from 21 to 56 (mean 38.1). Participants described themselves as white British (N 23), white Irish (N 3), white other (N 2), black African (N 1), black other (N 1), Asian Indian (N 2), and other ethnic background (N 5). Ethnicity data were not available for 13 participants. Measures Schizotypal Personality Scale The Schizotypal Personality Scale (STA; Claridge and Broks, 1984) is a measure of schizotypal personality consisting of 37 forced-choice items. The STA has been found to have good internal consistency (.85; Rawlings et al., 2001). A recent factor analysis of the scale suggested four factors: (1) magical thinking, (2) paranoid suspiciousness, (3) unusual perceptual experiences, and (4) social anxiety (Rawlings et al., 2001). State Dissociation Questionnaire The State Dissociation Questionnaire (SDQ) is a 9-item questionnaire measuring peritraumatic dissociation. It has been shown to have good internal consistency (.91; Halligan et al., 2003), and good reliability and validity (Murray et al., 2002). Posttraumatic Stress Diagnostic Scale On the Posttraumatic Stress Diagnostic Scale (PDS; Foa, 1995), participants rate how much they were affected by each of the PTSD symptoms specified in DSM-IV (American Psychiatric Association, 1994). Items range from 0 ( never ) to 3 ( five times per week or more/nearly always ). The symptom severity scale (part 3) has been shown to have good internal consistency (.91) and good test-retest reliability (r 0.74; Foa et al., 1997). The PDS contains subscales associated with the diagnostic criteria for PTSD: re-experiencing (5 items), avoidance (7 items), and arousal (5 items). Item 22 specifically assesses the frequency of unwanted thoughts or images in relation to the index trauma. Beck Depression Inventory The Beck Depression Inventory (BDI; Beck et al., 1961), a 21-item self-report questionnaire, measures depressive symptomatology. It has been found to have good internal consistency ( ; Beck et al., 1988). Beck Anxiety Inventory The Beck Anxiety Inventory (BAI; Beck and Steer, 1990) is a self-report questionnaire that measures physical and cognitive symptoms of anxiety. It has been found to have good test-retest reliability (r 0.75; Beck et al., 1988). Procedure A questionnaire pack was sent to people who were on waiting lists for psychological therapy after they had experienced a distressing or traumatic event. The pack included an invitation letter, information sheet, consent form, the STA, and the SDQ. If the service did not routinely send out the BDI, BAI, and the PDS, then these were also included in the research pack. Where services did routinely sent out their own copies of the PDS, BAI and BDI, then for some participants there was a time difference between the completion of the PDS, BDI, and BAI and the rest of the research pack (mean time difference 6.3 weeks). RESULTS Statistical Analyses 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. Distressing Events and PTSD Symptomatology Index events included serious accident, fire or explosion (N 17), nonsexual assault by unknown assailant (N 7), sexual assault by known assailant (N 6), sexual assault by unknown assailant (N 3), sexual contact under 18 with a person 5 years older (N 4), imprisonment (N 2), life-threatening illness (N 2), nonsexual assault by a known assailant (N 1), natural disaster (N 1), and other traumatic event (N 7). There was a mean of 2.6 (range 1 6) previously experienced traumatic events. The mean PDS severity score (32.8, SD 12.4) was similar to that found in the PTSD sample of Foa et al. (1997; 33.6, SD 9.9). Five of the sample exhibited acute posttraumatic symptomatology, while 32 exhibited chronic PTSD symptoms (duration over 3 months). Positive Schizotypy and Posttraumatic Symptomatology The number of respondents, means, SDs, and ranges for all questionnaires are shown in Table Lippincott Williams & Wilkins 61

3 Marzillier and Steel TABLE 1. Descriptive Statistics for the Measures of Positive Schizotypy, Peritraumatic Dissociation, PTSD Symptomatology, Intrusions, and Anxious and Depressed Mood Questionnaire N Mean SD Range STA SDQ PDS BDI BAI STA, Schizotypal Personality Scale; SDQ, State Dissociation Questionnaire; PDS, Posttraumatic Stress Diagnostic Scale; BDI, Beck Depression Inventory; BAI, Beck Anxiety Inventory. As shown in Table 2, there was a significant positive relationship between the STA and general posttraumatic symptomatology (PDS). There was also a significant positive relationship between the STA and the specific posttraumatic symptoms of re-experiencing, as measured both by the PDS re-experiencing subscale as a whole and item 22 in particular. With reference to the STA, all four subscales showed a significant positive relationship with general posttraumatic symptomatology. However, only the magical thinking subscale was significantly related to the re-experiencing subscale of the PDS and item 22. The SDQ was not significantly associated with the STA or any of its subscales. A significant positive relationship was found between the SDQ and general posttraumatic symptomatology, but not with the re-experiencing subscale of the PDS, or with item 22 in particular. Significant positive relationships were also found between the STA and the BDI and BAI, as well as between the SDQ and the BDI and BAI. Index traumatic event was grouped into two categories: (1) noninterpersonal (serious accident, fire or explosion, natural disaster, life threatening illness, other; N 26); and (2) interpersonal (nonsexual assault by known or unknown assailant, sexual assault by known or unknown assailant, sexual contact under 18, imprisonment; N 24). A median split was conducted on the STA to create two groups of schizotypes (high and low scorers). Two 2 2 ANOVAs were conducted using type of trauma and STA group as the independent variables. The dependent variables were PDS total score or PDS re-experiencing symptoms. In both cases, only STA group had a significant effect (p and p 0.017, respectively). There were no significant interaction effects of type of trauma and STA group (F 1,46.05, p 0.82; F 1,46.05, p 0.83, respectively) suggesting that type of trauma does not affect the relationship between the STA and posttraumatic symptoms. Nonparametric correlations showed that previous trauma history was not related to either general posttraumatic symptomatology, or re-experiencing in particular (PDS, r 0.07, p 0.65; re-experiencing, r 0.08, p 0.63). DISCUSSION To our knowledge, this is the first study to report the relationship between positive symptom schizotypy and posttraumatic symptomatology within a clinical sample who are seeking psychological interventions. The main finding was that high scoring positive schizotypes were vulnerable to suffering re-experiencing symptoms as a whole, and intrusive experiences in particular, after suffering a stressful or traumatic event. Further, high schizotypes were also vulnerable to other posttraumatic symptoms, i.e. hypervigilance and avoidance, within the week preceding the study. The current findings therefore extend the results of previous studies that have shown high schizotpyes are vulnerable to trauma-related intrusions within a short time frame after watching a stressful film (Holmes and Steel, 2004). These results are particularly important given that currently, so little is known about the impact of trauma on different personality types. Further findings of interest are the significant relationships between high levels of positive schizotypy with a posttraumatic increase in anxious and depressed mood. Clearly a vulnerability to increased levels of intrusive experiences may form the basis for increased avoidance of triggers for intrusions and the associated impact on mood. The personality trait of positive schizotypy was shown not to be associated with increased levels of dissociation during the trauma, a result in line with Holmes and Steel (2004). However, higher levels of peritraumatic dissociation were associated with posttraumatic symptomatology as a whole, supporting previous findings (Ozer et al., 2003). The current study did not support previous findings that schizotypal TABLE 2. Pearson Correlations Between the Measures of Intrusion Frequency, PTSD Symptomatology, Schizotypy, Peritraumatic Dissociation, and Depressed and Anxious Mood PDS PDS: Re-Experiencing PDS: Item 22 SDQ BDI BAI STA: Total 0.54** 0.34* 0.31* ** 0.35* STA: Unusual Perceptual Experiences 0.38** ** 0.17 STA: Magical Thinking 0.55** 0.50** 0.30* ** 0.56** STA: Paranoid Suspiciousness 0.47** ** 0.19 STA: Social Anxiety 0.34* * 0.29* SDQ 0.29* BDI 0.73** 0.55** 0.39** 0.31* 0.61** BAI 0.69** 0.68** 0.40** 0.27* **p 0.01; *p STA, Schizotypal Personality Scale; SDQ, State Dissociation Questionnaire; BDI, Beck Depression Inventory; BAI, Beck Anxiety Inventory Lippincott Williams & Wilkins

4 Schizotypy and Trauma-Related Intrusions personality is associated with a specific sensitivity to interpersonal trauma (Yen et al., 2002), although the sample sizes were small when trauma type was divided. It is important to consider that participants completed the schizotypy questionnaire after experiencing the stressful or traumatic event, and that consequently posttraumatic experiences may have influenced their response to some of the items. Indeed, very few truly prospective studies have examined the relationship between personality type and traumatic intrusions given these inherent difficulties. However, the measure of positive schizotypy was administered with explicit instructions that the items referred to long-term experiences and beliefs, and not posttraumatic changes. If participants had failed to adhere to these instructions, it is possible that some items on the unusual perceptual experiences scale may be positively responded to on the basis of the experience of posttraumatic intrusions. It is less likely that the other schizotypy subscales, such as the magical thinking items, which refer to paranormal beliefs and superstition, would be influenced in this way. However, given the limits of correlational studies, it is worth considering the current results as an extension to a previous analogue study in which positive schizotypy was assessed at the same time as exposure to a stressful film (Holmes and Steel, 2004). The current results are consistent with the theoretical account of schizotypy as a vulnerability factor for traumarelated intrusions put forward by Steel et al. (2005). This account draws on an existing cognitive model of psychosis (Hemsley, 1993), in which it is argued that the positive symptoms of schizophrenia are the product of uncontrollable intrusions from long-term memory. Hemsley (1993) states that during an acute stage of psychosis, individuals fail to process incoming information in a manner that is effectively integrated into a temporal and spatial context. It is argued that the strength of this contextual integration, which occurs during encoding, influences the subsequent frequency and nature of subsequent intrusive experiences. Steel et al. (2005) extend this argument to the continuum approach to psychosis, and suggest that high positive schizotype individuals may also exhibit a weakened ability to contextually integrate information and may also, at a lower level, be vulnerable to intrusive experiences. Indeed, the occurrence of regular intrusions may contribute to the beliefs and experiences that constitute a high schizotype personality. Steel et al. (2005) also draw on recent cognitive models of PTSD which seem to suggest that a process similar to weakened contextual integration occurs during traumatic hotspots, resulting in memories of the traumatic events being vulnerable to being triggered as an intrusion or flashback. The model of PTSD by Ehlers and Clark (2000) refers to the data-driven processing that occurs during a trauma, and reflects a basic perceptual level of information processing in which traumatic stimuli are not integrated into a context. By integrating cognitive models of both PTSD and psychosis, Steel et al. (2005) suggest that high schizotypes may be particularly vulnerable to traumarelated intrusions as they already exhibit a baseline level of information processing that contains weakened contextual integration. Thus, the experience of a traumatic event would, relative to low schizotypes, have a larger impact on their ability to integrate contextually and leave them particularly vulnerable to intrusions. While the current data, and the theoretical context within which they has been discussed, might suggest high schizotypes are particularly vulnerable to developing PTSD, there has been increasing evidence that schizotypy is a vulnerability factor for the transition to psychosis (Johnstone et al., 2005; Mason et al., 2004). It may of course be that schizotypal personality traits are a vulnerability factor for both disorders. However, it is of interest to consider that if high scoring schizotypes are vulnerable to intrusions from a wide range of stressful and traumatic events, it may become difficult for some high schizotype individuals to be able to identify the origin of the intrusions they experience as a memory. Within such a situation, individuals will draw upon their existing belief system to try and make sense of the confusing contents of their consciousness. Given that high schizotypes frequently hold beliefs regarding clairvoyance, telepathy, and the paranormal, it may be that these individuals are prone to appraising frequent, distressing intrusions as the product of some external force interfering with the contents of their mind. Clearly, the processes involved in this potential route to psychosis require further research. The clinical implications of the current study would seem to add to the growing need for the awareness of the role of trauma in psychosis. In particular, it may be that individuals with psychosis are suffering from posttraumatic intrusions that are difficult to identify when the more florid positive symptoms mask the intrusive experiences (Mueser et al., 1998). Further, it may be that idiosyncratic appraisals of these intrusive experiences contribute to ongoing psychotic beliefs and the associated distress. The results of the current study should be considered within the limitations of a small sample size and low response rate. It is also possible that an unmeasured variable may account for the relationship between those currently assessed. Given the importance of the issues being discussed, and the relative lack of current understanding, it would seem that further research investigating the role of positive schizotypy and the experience of traumatic events as a vulnerability factor for psychotic symptomatology is warranted. CONCLUSION The current study supports previous analogue research (Holmes and Steel, 2004) suggesting that schizotypy is a vulnerability factor for trauma-related intrusions. Further, it would seem that individuals scoring high in positive schizotypy are also vulnerable to the wider range of posttraumatic symptomatology, including hypervigilance and avoidance, after suffering a real-life stressful or traumatic event. These findings may have implications for the understanding of individual vulnerability to both PTSD and psychosis. ACKNOWLEDGMENTS The authors are grateful to Emily Holmes, Peter Scragg and Chris Brewin for their contributions to the study. Thanks are also due to the staff and service users at the 2007 Lippincott Williams & Wilkins 63

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