Psychophysiology of the Defense Cascade and its Relation to Posttraumatic Stress Disorder

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Psychophysiology of the Defense Cascade and its Relation to Posttraumatic Stress Disorder

Dissertation

zur Erlangung des akademischen Grades des Doktors der Naturwissenschaften (Dr.rer.nat)

an der

Mathematisch-Naturwissenschaftliche Sektion Fachbereich Psychologie

vorgelegt von Schalinski, Inga

Tag der mündlichen Prüfung: 25.02.2013 1. Referent: Prof. Dr. Thomas Elbert 2. Referent: Prof. Dr. Brigitte Rockstroh

Konstanzer Online-Publikations-System (KOPS) URL: http://nbn-resolving.de/urn:nbn:de:bsz:352-225065

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Acknowledgement

Firstly, I would like to thank my advisor Thomas Elbert- for his constructive recommendations, guidance and inspiration. I would like to express my gratitude to Brigitte Rockstroh for her research contributions, openness and impressive scientific passion.

This project would not have been possible without the support from the Deutsche Forschungsgemeinschaft (DFG) and the European Refugee Fund. I thank the respondents who participated in the study with great courage and willingness. I also appreciate the support from the translators and those people and organizations that referred patients to the project. I am also grateful to Heike Riedke and Dagmar Moret for the logistical support and the Outpatient Clinic for refugees at Konstanz University. I would like to thank the following colleagues for their assistance and patience with the data collection: Alexandra Geist, Char- lotte Salmen, Franziska Unholzer and James Moran. A very special thanks goes to Patrick Berg for his rapid recommendations. Further, I would like to offer special thanks to Michael Odenwald for the clinical advice. I would also like to extend my thanks to the technicians of the MEG laboratory for their help in setting up data collection, especially Ursula Lommen for her support. Further I owe thanks to Christiane Wolf who supported the saliva cortisol as- sessments and the acquisitions of the MRIs. I am obliged to many of my colleagues who supported me. Especially, I would like to thank Claudia Bueno and Wessam Mohammed.

Finally, I would like to thank my family and friends. Thanks and hugs to Ken for the native Southern American English and just being there through the time of writing. Thanks y’all.

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Records of Achievement

Article 1: Female dissociative responding to extreme sexual violence in a chronic crisis setting: the case of Eastern Congo (published in Journal of Traumatic Stress, 2011, 24, 235- 238)

Inga Schalinski, Thomas Elbert, Maggie Schauer My contributions:

-‐ carried out the majority of the clinical interviews -‐ conducted the statistical analysis

-‐ drafted the manuscript.

Article 2: Cardiac defense in response to imminent threat in women with multiple trauma and severe PTSD (accepted in Psychophysiology)

Inga Schalinski, Thomas Elbert, Maggie Schauer My contributions:

-‐ carried out the majority of the clinical interviews -‐ carried out the physiological recordings

-‐ developed scripts to assess and analyse the heart rate data -‐ conducted the statistical analysis

-‐ drafted the manuscript

Article 3: Dissociation, PTSD and depression modulate early visual emotional processing. An MEG study (unpublished manuscript)

Inga Schalinski, James Moran, Thomas Elbert My contributions:

-‐ carried out the majority of the clinical interviews -‐ carried out the physiological recordings

-‐ carried out the data preprocessing

-‐ developed scripts to analyse the event-related magnetic fields -‐ drafted the manuscript

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Summary

The present thesis explored the link between dissociative responding, posttraumatic stress disorder (PTSD) and depression as well as physiological and neurophysiological responses in female survivors with cumulative trauma exposure. Controversial psychophysiological responses have raised the question of a dissociative PTSD subtype. Until now, the link between dissociation and PTSD remains a source of conceptual controversy (van der Hart, Ni- jenhuis, Steele & Brown, 2004). Based on the defense cascade model “Freeze-Flight-Fight- Fright-Flag-Faint” a new questionnaire was drafted, the Shutdown Dissociation Scale, and applied to assess the conceptual proposed symptoms of shutdown dissociation (Schauer &

Elbert, 2010). Research about the physiology, endocrinology and neurophysiology in PTSD and dissociative responding has relied almost exclusively on comparative methodological designs. Due to the limited knowledge whether dissociative responding is a core feature of a distinct group of severe PTSD or a dimensional continuum of posttraumatic stress symptoms, the present work focuses on a dimensional approach. In female samples, traumatic experiences, symptom levels (PTSD, depression and shutdown dissociation) as well as physiological data (heart rate and brain responses) were assessed.

In the first study we applied the shutdown dissociation scale to female survivors of the extreme sexual violence in the ongoing war in Eastern Congo. Further, the various traumatic event types that were self-experienced and the number of different traumatic event types that were witnessed as well as current PTSD and depression symptoms were assessed. The findings emphasize the importance of shutdown dissociation in elevated PTSD and confirm that the trauma exposure, dissociation, PTSD and depression symptom severity are inherently related. A path-analytic approach is proposed to disentangle the interrelations. Differential effects on PTSD symptom severity could be observed for threat to oneself (higher proximity of danger) as opposed to witnessing trauma (lower proximity to danger). PTSD symptom severity had the highest common variance with depression. Further, PTSD symptom severity seems to mediate the relationship between dissociative responding and depression symptoms.

In the second study, the physiological responding in women with and without PTSD was investigated using the cardiac defense paradigm. Whereas the Non-PTSD group showed a decrease after the first acceleration, the PTSD group showed elevated heart rate responses.

The elevation was associated with an ongoing withdrawal of the parasympathetic influence.

Additionally, the elevation in the heart rate was also found when the relationship was con- trolled for the cumulative trauma exposure, arguing for an augmented PTSD level for those

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Summary 9

that have increased heart rates. Differential effects regarding the trauma’s proximity of danger were observed. Our results suggest that multiple exposure to life-threat followed by PTSD can on the one hand bring long lasting psychophysiological changes and on the other hand support the hypothesis of elevated heart rate responding for severe traumatized women with PTSD.

In the third study, the emotional processing of pictorial stimuli was assessed in women with and without PTSD. The rapid serial visual presentation paradigm was used to investigate the emotional processing of unpleasant, pleasant and neutral photographs. PTSD patients showed deviant affective processing from the Non-PTSD group indicated by differences in valence and arousal ratings. Further, both groups rated the unpleasant pictures as more arousing compared to pleasant pictures. In line with the difference in arousal ratings, the heart rate data confirmed a higher physiological arousal in the unpleasant/ neutral block compared to the pleasant/ neutral block for both groups. Event-related magnetic fields were recorded during streams of emotionally arousing (unpleasant or pleasant) stimuli that alter- nated with pictures from negligible affective content (neutral). Neural sources were esti- mated for each condition based on the L2 surface-minimum-norm. An early (mean from 60 to 110 ms) response differentiation between the high versus low arousal conditions were found in the PTSD group, but only a modulation of the early response between unpleasant and neutral stimuli in the Non-PTSD group. Relationships of shutdown dissociation, the degree of PTSD and depression symptom severity with the brain activities (60 to 110 ms and (228 to 245 ms) were explored and these variables seem to be involved in the cortical network of visual emotional processing. In sum, these results would support a model that suggests that with increasing exposure to traumatic stress, brain processing becomes altered on qualitatively different dimensions, as captured by symptoms of PTSD, depression and dissociation.

The present thesis applied a dimensional approach on clinical, physiological and neural data. With the dimensional approach, significant within group variation of physiological and brain responses could be explained by symptom levels of shutdown dissociation, PTSD and depression. A model of different physiological responses in PTSD is proposed and treatment implications as well as proposals for the fifth edition of the Diagnostic and Statisti- cal Manual of Mental Disorder (DSM) are discussed.

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Zusammenfassung

Die vorliegende Arbeit untersucht die Beziehung zwischen dissoziativen Symptomen, Post- traumatischer Belastungsstörung (PTBS) und Depression sowie physiologischen und neurophysiologischen Reaktionen in weiblichen Überlebenden multipler traumatischer Erfahrun- gen. Kontroverse Ergebnisse aus physiologischen Studien deuten auf einen dissoziativen Subtypen der PTBS hin. Der theoretische Zusammenhang zwischen Dissoziationen und PTBS ist jedoch bis heute kontrovers diskutiert (van der Hart, Nijenhuis, Steele & Brown, 2004). Basierend auf dem Abwehrkaskadenmodell “Freeze-Flight-Fight-Fright-Flag-Faint“

wurde ein neuer Fragebogen entworfen, die Shutdown Dissociation Scale, und anwendet um speziell die aus dem Model hervorgehenden psychophysiologischen Dissoziationssymptome zu erfassen (Schauer & Elbert, 2010). Wissenschaftliche Studien der physiologischen, endo- krinologischen und neurophysiologischen Reaktionen bei Probanden mit PTBS und dissoziativen Symptomen wurden bislang fast ausschließlich in Gruppenvergleichen untersucht. Je- doch bleibt die Frage offen, ob dissoziative Symptome ein Kernmerkmal einer Untergruppe der PTBS betreffen oder ob sie ein dimensionales Kontinuum von posttraumatischen Sym- ptomen darstellt. Daher wurde in dieser Arbeit auf einen dimensionalen Ansatz zurückge- griffen. Bei Frauen wurden traumatische Erfahrungen, Symptomausprägungen (PTBS, De- pression und dissoziative Symptomatik) sowie auch physiologischen Daten (Herzratenverän- derungen und kortikale Aktivität) erhoben.

In der ersten Studie wurde die neu entwickelte Skala in einer weiblichen Stichprobe von Überlebenden sexueller Gewalt des Ostkongo Konfliktes angewendet. Auch wurden die verschiedenen traumatischen Erfahrungen, die selbst erlebt sowie bezeugt wurden und die PTBS- und Depressionsschwere erfasst. Die Ergebnisse bestätigten die Bedeutung von dissoziativen Reaktionen in schwererer PTBS und wiesen auf Interkorrelationen zwischen den Variablen hin. In einem pfadanalytischen Modell wurden die unterschiedlichen Einflüsse von Dissoziationen, der Anzahl selbsterlebter und bezeugter Traumaereignistypen auf die PTBS Schwere und Depression untersucht. Differenzielle Effekte wurden für die Traumae- reignistypen mit eigener Bedrohung (geringer Distanz zur Gefahr) im Vergleich zu bezeugten Traumaereignistypen (größerer Distanz zur Gefahr) beobachtet. Die PTBS und Depressions- schwere wiesen weiterhin einen starken Zusammenhang auf. Wenn die PTBS Schwere be- rücksichtigt wurde, schwand die Korrelation zwischen Depressions- und Dissoziationssymp- tomen.

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Zusammenfassung 11

In der zweiten Studie wurde die physiologischen Reaktionen der Herzrate bei Frauen mit und ohne PTBS mit dem kardialen Abwehr Paradigma untersucht. Wohingegen die Nicht-PTBS Gruppe eine abnehmende Herzrate nach der ersten Herzratenbeschleunigung zeigte, wurde eine anhaltende erhöhte Herzrate in der PTBS-Gruppe beobachtet. Die erhöhte Herzrate wird mit einer anhaltenden Entziehung des parasympathischen Einflusses auf die Herzrate in Verbindung gebracht. Außerdem korrelierte die Herzrate mit der PTBS Sym- ptomschwere. Diese positive Korrelation bestand weiterhin, auch unabhängig von der An- zahl traumatischer Erfahrungen. Das spricht für erhöhte PTBS Symptomausprägungen für die Personen, die höhere Herzraten aufwiesen. Wie auch in der ersten Studie, wurden die Ereignistypen nach eigener und bezeugter Bedrohung getrennt untersucht. Differenzielle Effekte konnten für die Anzahl von Ereignistypen mit geringer Distanz zur Gefahr beobachtet werden. Die Ergebnisse sprechen einerseits dafür, dass kumulierte traumatische Erfah- rungen und PTBS lang anhaltende psychophysiologischen Veränderungen mit sich bringen und andererseits wird die Hypothese untermauert, dass erhöhte Herzratenreaktionen auch für schwer traumatisierte Frauen mit PTBS gefunden werden können.

In der dritten Studie wurde die emotionale Verarbeitung von Bildern in einer Stich- probe von Frauen mit und ohne PTBS untersucht. Das schnelle, serielle, visuelle Präsentati- onsparadigma wurde verwendet um die emotionale Verarbeitung von negativen, positiven und neutralen Fotographien zu erfassen. Die Bewertung der Valenz und Erregung der Bilder deutete auf eine unterschiedliche Verarbeitung zwischen der PTBS Gruppe und der Nicht- PTBS Gruppe hin. Außerdem bewerteten beiden Gruppen die negativen Bilder als erregen- der als die positiven Bilder. Dieser Unterschied zeigte sich auch auf physiologischer Ebene in einer erhöhten Herzrate für beide Gruppen bei der seriellen Präsentation negativer im Ver- gleich positiver Bilderblöcke. Ereigniskorrelierte magnetische Felder wurden für die emotional erregenden Stimuli (negativ und positiv), die mit neutralen Bildern gemischt in Blöcken präsentiert wurden, aufgezeichnet. Kortikale Quellenaktivität wurde für jede Bedingung mit Hilfe der L2- Oberflächen-Minimumnorm geschätzt. Bereits in einem frühen Zeitfenster (von 60 bis 110 ms) unterschied sich die kortikale Aktivität auf Quellenebene zwischen den hoch erregenden und niedrig erregenden Bilderkategorien in der PTBS Gruppe, während sich dieser Unterschied nur zwischen den negativen und neutralen Reizen in der Nicht-PTBS als bedeutsam erwies. Korrelate der kortikalen Aktivität auf Quellenebene (von 60 bis 110 ms) und (von 228 bis 245 ms) wurde im Bezug auf die Symptomausprägungen berechnet (PTBS und Depression sowie dissoziative Reaktionen während der Betrachtung der Bilderserie).

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Die Symptomausprägungen zeigten einen Einfluss auf die kortikale Verarbeitung von visuel- len emotionalen Reizen. Abschließend sprechen diese Ergebnisse für ein Model, dass mit multiplen traumatischen Erfahrungen und Traumaspektrumsstörungen (erfasst als Symptome der PTBS, Depression und dissoziativen Reaktionen), die kortikalen Verarbeitungsprozesse in qualitativ unterschiedlichen beeinflusst werden.

Die vorliegende Arbeit verwendete einen dimensionalen Ansatz an um die psychopa- thologischen, physiologischen und neuronalen Daten auszuwerten. Mit diesem Ansatz konn- te gezeigt werden, dass bedeutsame Varianzanteile der physiologischen und der neuronalen Aktivität durch die Symptomausprägungen (dissoziativer Reaktionen, PTBS und Depression) aufgeklärt werden können. Die Daten der zweiten Studie weisen darauf hin, dass dissoziative Symptomatik nicht grundsätzlich mit einer unterdrückten physiologischen Herzratenreaktion einhergeht. Die Beziehung zwischen Dissoziationen und Übererregung, therapeutische Im- plikationen sowie Vorschläge für die fünfte Auflage des Diagnostischen und Statistischen Handbuchs Psychischer Störungen (DSM) werden diskutiert.

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Introduction 13

1. Introduction

Historically, the relationship between dissociation and trauma dates back to the 19^th century (Briquet, 1859; Janet, 1889). Until now, the link between dissociation and posttraumatic stress disorder (PTSD) remains a source of conceptual controversy (van der Hart, Ni- jenhuis, Steele & Brown, 2004). Dissociation refers to an alternation of the usually inte- grated functions of consciousness, memory, sense of time, body awareness, and perceptions of the environment and the self (Diagnostic and Statistical Manual of Mental Disorder-IV (DSM-IV), American Psychiatric Association, 1994). An evolutionary based model could further the understanding of trauma and dissociation (Schauer & Elbert, 2010). Being con- fronted by life threatening situations, cognitive and motivational adaption play an important role in ensuring the survival. The defense cascade model “freeze-flight-fight-fright-flag- faint” consists of adaptive processes to enhance survival (Lang, Bradley & Cuthbert, 1998).

In life threatening situations, initially, the ongoing perceptual and behavioral processes would be interrupted followed by an enhanced sensory perception towards the threatening stimulus (Graham, 1966; Sokolov, 1963). Porges (2006) suggests that the unmyelinated vagal system is responsible for the reduced cardiac output, which is associated with immobile behavior.

This defense stage presents a transient mechanism and may serve as a preparation of active defense responses such as flight or fight (Bracha, 2004). If the stimulus is threatening then the sympathetic branch of the autonomous nervous system becomes dominant and the release of sympathetic mediated adrenalin is initiated. This bodily adaption supplies the heart and muscles with the required energy for flight or fight. At the same time, the peripheral vessels constrict in order to reduce the potential blood loss in the case of injury. Further the breath- ing changes in order to supply the body optimally with oxygen. In life-threat with extreme fear and physical restraint “fright” or tonic immobility is common (Bracha, 2004). Research with laboratory animals has shown that the termination of tonic immobility is typically abrupt (Gallup, 1977). Reports about tonic immobility from rape survivors describe similar states in humans (Bovin, Jager-Hyman, Gold, Marx & Sloan, 2008; Galliano, Noble, Travis & Puechl, 1993; Fusé, Forsyth, Marx, Gallup & Weaver, 2007). The defense responses escalate as a function of proximity to danger (Bracha, 2004; Marx, Forsyth & Lexington, 2008) and of individual defense possibilities. Maximal proximity such as penile penetration during rape is associated with more dissociative responding (Johnson, Pike & Chard, 2001). Whereas an adult more likely possesses the strength or the power for flight or fight, a child is more likely to show dissociative responding (Heidt, Marx, Forsyth, 2005; Romans, Martin, Morris &

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Herbison, 1999). The stages “fright-flag-faint” present further progression on the defense cascade. Dissociative responding consists of functional sensory deafferentation, motor paralysis, alternations of the consciousness and loss of speech perception and production. Ap- parently, traumatic events that involve intense fear, in the presence of fluids with risk of con- tamination (e.g. blood or sperm), perceived ongoing inescability, or a high proximity to danger during life-threat may provoke shutdown dissociation (Marx et al., 2008; Heidt et al., 2005; Schauer & Elbert, 2010). To shutdown the bodily system, the parasympathetic system takes over the dominance resulting in bradycardia, decrease in blood pressure and vasodilata- tion (Scaer, 2001; Schauer & Elbert, 2010). The dorsal vagal complex in the medulla may increase its activity during dissociative responding (Porges, 1995). “Fright-flag-faint” becomes adaptive when there is no perceived possibility to “flight or fight”. It enhances the survival, because the predator may loose the interest under the assumption that the prey is dead. In contrast to the tonic immobility, the onset of shutdown dissociation is usually slow with a long recovery time. An abrupt onset can only be observed when dissociative responding is conditioned (Bolles and Fanselow, 1980; Schauer & Elbert, 2010).

Figure 1.1: Schematic illustration of the defense cascade model as it progresses along the different defense stages. The active defense stages are presented on the ascent of the curve and the set of dissociative defense stages on the descent.

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Introduction 15

Numerous retrospective studies show that peritraumatic dissociation plays a key role in the development of PTSD (see Ozer, Best, Lipsey, Weiss, 2003 for review; Ehlers, Mayou &

Bryant, 1998; Shalev, Peri, Canetti & Schreiber, 1996; Weiss, Marmar, Metzler, Ronfeldt, 1995). It is assumed that the peritraumatic responding is linked to a more disturbed immedi- ate memory encoding and processing of the traumatic experiences (van der Kolk & Fisler, 2007). Despite this convincing data, some studies failed to find a significant relationship between peritraumatic dissociation and subsequent PTSD (Harvey & Bryant, 2002).

Whereas a large amount of studies have focused on peritraumatic dissociation, the persistence of these symptoms was long time overlooked. The results of those studies argue for a more central role of ongoing dissociative responding (Briere, Scott & Weathers, 2005; Murray, Ehlers & Mayou, 2002; Panasetis & Bryant, 2003; Werner & Griffin, 2012). Briere, and colleagues (2005) suggest that it is possible that peritraumatic and persistent dissociation reflect the same phenomenon, but the time course plays a critical role. Their results show, that the association of peritraumatic dissociation and PTSD vanish when the relationship was con- trolled for persistent dissociation. Ongoing dissociation pertains perceptual, somatosensoric and sensual functions (Nijenhuis, Spinhoven, van Dyck, van der Hart & Vanderlinden, 1996) and interferes with an integrative representation of the environment and the self (Schauer &

Elbert, 2010). It is likely that the ongoing disruption of integrative processes would play a key role in the development and maintenance of PTSD. Dissociative responding could then be understood on one hand as an adaption in order to survive during life-threat and on the other hand as a problem resulting in more fragmentation of the past and future memories.

The autobiographical representation of the traumatic memory is disturbed in PTSD (e.g. McNally, Lasko, Macklin, Roger & Pitman, 1995). Traumatic memories consist of sensory-perceptual representations as well as cognitive and physiological elements. Repeated exposure to different traumatic event types forms a fear-network that is pathologically de- tached from the context representations (information of where and when), leading to frag- mented memories in patients with PTSD (Elbert, Rockstroh, Kolassa, Schauer & Neuner, 2006). Intrusive memories as well as flashbacks can re-occur at any time when the fear- network is triggered. The intrusion can be understood as displays of elements of the traumatic event, which can also be accompanied by the dominating physiological response during the traumatic event e.g. sympathetic arousal or dissociative symptoms (Lang, Bradley &

Cuthbert, 1998; Rockstroh & Elbert, 2010). In figure 1.2 the fear-network of one survivor of a sexual assault and vehicle accident is illustrated with both sympathetic and parasympathetic

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physiological elements. With repeated exposure to different traumatic event types, the fear- network increases its interconnection between representations of different events and strengthens the network. The parasympathetically dominated shutdown of sensory, functional and bodily systems can reoccur whenever the fear-network is triggered e.g. in confrontation with intrusions, minor stressors or during trauma exposure therapy. Adaptive recovery from traumatic memories requires the reactivation of the elements of the fear-network to be coupled with the contextual features. Accordingly, avoidance and dissociative responding after trauma prevent the recovery, because of suppressed affective involvement (Jaycox, Foa

& Morral, 1998).

Figure 1.2: Example of a fear-network memory of two different types of traumatic events (sexual assault and vehicle accident). In the upper part traumatic memory features (sensory contents in the ellipse, emotional contents in the pointy cloud, physiological information in the rectangle and cognitions in the think clouds) are shown. The autobiographical content is presented in the lower part. While the elements in the upper part are fairly interconnected, the autobiographical information is weakly associated to the sensory, emotional, cognitive and physiological features. The arrows in the rectangle boxes refer to sympathetic dominance ↑ and parasympathetic dominance ↓ of the autonomous nervous system.

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Introduction 17

1.2 Dissociative Responding and its Interrelations

Current research confirms the link between dissociative responding and trauma, par- ticularly in association with severe/ multiple and/ or sexual abuse in childhood (Ginzburg et al., 2006; Heidt et al., 2005; Romans et al., 1999). Interpersonal trauma (e.g. physical and sexual assault) seem to be more associated with PTSD than other potentially traumatizing event types such as accidents or natural disasters (Kessler, Sonnega, Bromet, Hughes & Nel- son, 1995; Resnick, Kilpatrick, Dansky, Saunders & Best, 1993). Increased levels of dissociation were also found in refugees or battered women (Carlson & Rosser-Hogan, 1991;

Weaver & Clum, 1996). A greater exposure to trauma is related to higher levels of dissociation (e.g. Briere, Hodges & Godbout, 2010; Carlson & Rosser-Hogan, 1991). Moreover, dissociative responding is associated with more severe psychopathology such as PTSD, depression, self-harming and suicidality (e.g. Brewin, Andrews & Valentine, 2000; Feeny, Zoellner, Fitzgibbons & Foa, 2005; Mollica, McInnes, Poole & Tor, 1998; Weber et al., 2008; Werner & Griffin, 2012). Especially, PTSD diagnosis as well as symptom severity is associated with higher levels of dissociation (e.g. Briere et al., 2010; Halligan, Michael, Clark

& Ehlers, 2003; Murray et al., 2002). The positive associations were found for all the three symptom clusters of PTSD (intrusion, avoidance and hyperarousal) and dissociative responding (e.g. Steuwe, Lanius & Frewen 2012). The inherent relationship can be addressed in terms of symptom overlap of co-morbid entities. For example, emotional numbing is one of the core symptoms of PTSD, but could also be a manifestation of a severe depressive disorder. Further, emotional numbing describes a type of abnormal affective processing in dissociative responding as an emotional overmodulation. Further, dissociation may reflect the severity of PTSD: the upper end of the posttrauma stress symptoms (Hyer, Albrecht, Boudewyns, Woods & Brandsma, 1993; Dalenberg & Carlson, 2012). Taken together, the inherent relationship between psychopathology argues to go beyond categorical consider- ations and to focus on continuous dimensions of the symptoms that arise after traumatic stress.

1.3 The Course of Trauma-related Dissociation

The temporal pattern of trauma-related dissociative responding provides further possibilities regarding the link between trauma and dissociation. Several studies observed the dissociative responding in the aftermath of the trauma (e.g. Cardeña & Spiegel, 1993; Dancu, Riggs, Hearst-Ikeda, Foa & Shoyer, 1996). These studies show a decline in dissociative re-

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sponding as a function of the time elapsed since the traumatic event. In contrast, a study of Halligan and colleagues (2003) found that the dissociative responding could increase over the time for those who had developed a PTSD. So far no studies have assessed how cumulative trauma affects the temporal pattern, but it has been shown that dissociative symptoms play a role even after months or years after the traumatic experiences (Carlson, Dalenberg and McDade-Montez, 2012).

Evidence suggests that the exposure-based treatment outcome is lower for patients with dissociative symptoms (Jaycox et al., 1998) and that the current treatment for PTSD may be insufficient. In contrast, another study found that dissociative responding decreases with changes of the PTSD symptom severity (Lynch, Forman, Mendelsohn & Herman, 2008). This link supports the view that both types of symptoms are psychopathologically and phenomenologically related.

1.4 Measures of Dissociative Responding

Beginning in the 1980s, an immense increase of interest of dissociation spurred efforts to develop scales of dissociative responding. The first studies about dissociation in PTSD used the Dissociative Experience Scale (Bernstein & Putnam, 1986). It is a self-rating scale that contains normal and pathological dissociative states. The Dissociative Experience Scale- II represents an update of the original questionnaire with a different response format (Carlson

& Putnam, 1993). Nowadays most of the studies still apply the self-rating scale since it was translated into the most frequent languages. Waller and Ross (1997) developed a subscale of the Dissociative Experience Scale that measures the pathological dissociation. Critic has risen regarding the construct validity and longitudinal stability of the scale (Giesbrecht, Lynn, Lilienfeld & Merckelbach, 2008). There are other types of self-rating questionnaires that measure dissociative responding e.g. the Multiscale Dissociation Inventory (Briere, Weathers

& Runtz, 2005) and the Somatoform Dissociation Questionnaire (Nijenhuis et al., 1996). The Clinician-Administrated Dissociative State Scale consists of a self-rating and ratings scored by a professional observer (Bremner et al., 1998). This questionnaire was applied in several neuroimaging studies (Lanius et al., 2002; 2005). Participants that endorse at least 15 symptoms on the Clinician-Administrated Dissociative State Scale were included in the dissociative subgroup. The Dissociation Subscale of the Trauma symptom Inventory (Briere, Elliot, Harris & Cotman, 1995) was applied as well in series of studies in PTSD. Further there are structured interviews to assess diagnostic criteria of dissociative symptoms such as Structured

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Introduction 19

Clinical Interview for DSM-IV (Steinberg, 1994) and Dissociative Disorder Interview Schedule (Ross et al., 1989). The Multidimensional Inventory of Dissociation is a 218-item self-administered instrument, especially for clinical research and diagnostic assessment (Dell, 2006). Further studies have focused on the peritraumatic response using retrospective self- ratings such as the Peritraumatic Dissociation Experience Questionnaire (Marmar et al., 1994; Marmar, Weiss & Metzler, 1997) or the Tonic Immobility Scale (Forsyth, Marx, Fusé, Heidt, & Gallup, 2000; Fusé et al., 2007).

To summarize, numerous measures of peritraumatic responses, persistent dissociative responses as well as diagnostic interviews of dissociative disorder exist and were applied in the context of dissociative responding in PTSD. Most of these instruments consist of self- rating items. In resource-poor settings, self-assessment seems to be unsuitable. Additionally, it is difficult to apply these questionnaires in low educated samples. We designed a structured interview to assess the tendency of shutdown dissociation: the Shutdown Dissociation Scale. Based on the defense cascade model by Schauer and Elbert (2010), the parasympathetic dominant responses are characterized by progressive symptoms of functional sensory deafferentation, reduced nociception, numbing, motor paralysis, loss of language functions, pseudoneurological symptoms and signs of pre-syncope (e.g. vomiting). The present thesis used the Shutdown Dissociation Scale as a measurement of the severity of dissociative responding (the Shutdown Dissociation Scale and administration information are attached in the appendix).

1.5 Physiological, Endocrinological and Neurobiological Differences and Correlates Research has begun to investigate the physiological, endocrinological and neurobiological differences as well as correlates of dissociative responding in PTSD. Larger startle responses are a robust physiological correlate of PTSD (Pole, 2007). Exaggerated physiological responding has also been found in samples of female nurse veterans and survivors of sexual assault (Carson et al., 2007; Metzger et al., 1999; Rothbaum, Kozak, Foa & Whitaker, 2001). Growing literature suggests that high dissociative PTSD patients show different autonomic responses. For example, Griffin, Resick and Mechanic (1997) examined a group of female rape survivors and found that those subjects with high peritraumatic dissociation ex- hibit lower heart rate and skin conductance when they were talking about their traumatic experiences. Further studies found evidence that ongoing traumatic stressors such as family violence were correlated with reduced startle reactivity in adult women (Medina, Mejia,

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Schell, Dawson & Margolin, 2001). Thus, it seems that although there is strong evidence for cardiac hyperreactivity in PTSD, there is also a significant number of studies showing an opposite hyporeactivity. It is clear that we need a different explanatory framework of PTSD and physiological response to reconcile these apparently contradictory findings. Current psychophysiological theories about the physiological reactivity in PTSD that could be observed in the laboratory state that it recapitulates the response that occurred during the trauma (e.g.

Lang et al., 1998). Whereas former views primarily focused on the sympathetic branch of the autonomic nervous system (DSM-IV, American Psychiatric Association, 1994; Buckely &

Kaloupek, 2001), the evolutionary based defense cascade model emphasizes that both parts of the autonomous nervous system the sympathetical and parasympathetical branch contrib- ute to the physiological responding. Thus, active defensive behavior, such as flight or fight, as well as passive defense behavior, such as fright-flag-faint, are adaptive to life-threat (Schauer & Elbert, 2010) and can therefore explain the differences in physiological studies.

Gola and colleagues (2011) investigated plasma and saliva cortisol in raped (high proximity to danger) and non-raped (lower proximity to danger) trauma survivors and found modula- tions of the cortisol response to a structured interview about the traumatic experiences. An- other study, that has focused on salivary cortisol found no evidence of differential responding during a stressful interview, but 24 hours later in high dissociative women (Koopman et al., 2003). Trauma-related symptoms such as anxiety, depression, sleep disturbances and dissociation predicted the cortisol responses in women in an interpersonal conflict task (Power et al., 2006). These studies suggest that dissociative responding is related to hypothalamic- pituitary-adrenal axis reactivity. Neuroimaging studies of the neuronal circuitry of traumatic memories suggest that there may be distinctive response patterns to trauma memories that distinguish individuals with dissociative from those with non-dissociative PTSD (Lanius et al., 2002; Lanius, Bluhm, Lanius & Pain, 2006). A subgroup of PTSD patients that showed more hyperarousal symptoms also displayed lower bilateral medial frontal activity and left anterior cingulate activity. Whereas a subgroup of patients with dissociative PTSD had increased right medial frontal, right medial prefrontal, right anterior cingulate activity compared to controls. The higher prefrontal activity seems to co-occur with reduced amygdala activity in dissociative PTSD. These results were interpreted as a form of emotional overmodulation in dissociative PTSD, whereas an emotional undermodulation mediated by less intensive prefrontal inhibition of the limbic system was found in non-dissociative PTSD (Lanius et al., 2010). To summarize, the current controversial physiological and endocri-

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Introduction 21

nological as well as neurophysiological findings suggest that there may be hints for a dissociative subtype in PTSD, but our knowledge of the role of dissociative responding is limited.

1.6 Group Comparison or Dimensional Approaches

Methodologically, dissociative responding following posttraumatic stress can be con- ceptualized in a qualitative approach, comparing subtypes or in a dimensional approach con- sidering symptom severities. Although there are individual differences in dissociative responding within the PTSD, the question arises whether those symptoms might predominate one distinctive subtype with elevated PTSD or whether those symptoms are distributed di- mensionally. Studies using taxometic or latent class analysis have addressed this question.

Waelde, Silvern and Fairbank (2005) examined 316 male trauma-exposed Vietnam veterans with the Dissociative Experiences Scale. They found that not all individuals who meet the criteria of PTSD, show high dissociative responding and there was a subgroup of high dissociative people without PTSD. Their results indicate that there is a distinctive subgroup of severe PTSD with higher levels of dissociative responding. Theses results are in line with the findings of Waller and Ross (1997). They identified a dissociative taxon that included 18%

of the PTSD sample, but the severity of PTSD was not considered in this study. In contrast to the findings, Ruscio, Ruscio and Keane (2002) found support for a continuous stress response with PTSD presenting the upper end of the dimension. Additionally, the results of the taxometric study of combat veterans (Forbes, Haslam, Willimas & Craemer, 2005) favour the uni-dimensional model of PTSD. A recent study of Wolf and colleagues (2012) examined male and female veterans that were exposed to a variety of traumatic experiences (e.g. combat experiences and sexual assaults). The latent structure analysis indicated a three group model (moderate, high and high PTSD coupled with dissociation) in male and female veterans. Furthermore, to support the subtype hypothesis, it is necessary to describe the symptom profiles and differentiating factors. Using signal detection analysis, Ginzburg and colleagues (2006) examined symptom profiles of low and high dissociative PTSD. A foreshortened future and two hyperarousal symptoms -hypervigilance and sleep difficulties- were more pro- nounced in high dissociative compared to low dissociative PTSD. A recent study by Steuwe and colleagues (2012) explored the symptom profile with a latent profile analyses and con- firmatory factor analyses and found evidence of a dissociative symptom cluster, that is correlated to the core PTSD symptoms and associated with higher PTSD symptom severity as well as more severe co-morbidity pattern. To conclude, inconsistent data exists about the question

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whether the dissociative symptoms occur in a distinct PTSD subgroup with a high symptom severity or whether there is a dissociative continuum within the PTSD.

1.7 The Rational of the Present Thesis:

Research about the physiology, endocrinology and neurophysiology in PTSD has relied almost exclusively on comparative methodological designs (comparing dissociative versus non-dissociative groups, raped versus non-raped or low and high dissociative samples).

The present thesis contributes to the research of trauma-related dissociation, and offers to consider the dissociative responding from a dimensional perspective. A newly developed questionnaire, the Shutdown Dissociation Scale, was drafted and applied to assess the conceptual proposed symptoms of shutdown of the defense cascade model. In female samples, traumatic experiences, symptom levels (PTSD, depression and shutdown dissociation) as well as physiological data (heart rate and brain responses) were assessed. Due to the limited knowledge whether dissociative responding is a core feature of a distinct group of PTSD or a dimensional continuum of posttraumatic stress symptoms, the present work focuses on dissociation in patients with PTSD investigating physiological and neurophysiologic responses.

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2. Female Dissociative Responding to Extreme Sexual Violence in a Chronic Crisis Setting: The Case of Eastern Congo

2.1 Abstract

The present cross-sectional study aimed to examine relationships between the number of traumatizing events, degree of shutdown dissociation, posttraumatic stress disorder (PTSD), and depression. Fifty-three female survivors of the ongoing war in Eastern Congo, who sought medical treatment, were interviewed. A path-analytic model was created with paths to PTSD via shutdown dissociation, the number of self-experienced and witnessed traumatizing event types. Cumulative trauma exposure and shutdown dissociation were associated with increased PTSD severity. PTSD and witnessing predicted depression when depression was modelled as a consequence of PTSD. Moreover PTSD mediated the correlation between dissociation and depression. The findings emphasize the power of shutdown dissociation in predicting PTSD and suggest differential effects of threat to oneself as opposed to witnessing trauma.

2.2 Introduction

Dissociative responding during and in the aftermath of trauma exposure has been observed in survivors who were exposed to serious threat with a proximity to danger, such as sexual assaults (Marx, Forsyth & Lexington, 2008). Persistent dissociation has been shown to be a powerful predictor of posttraumatic stress disorder (PTSD) (Briere, Scott & Weathers, 2005). In the present study, dissociation is regarded as a defence that typically appears in response to bodily proximity to danger. It includes partial or complete functional sensory shutdown, classified as negative dissociative symptoms (van der Hart, Nijenhuis & Steele, 2005). From an evolutionary perspective these shutdown dissociation might be adaptive in life-threatening conditions in which neither flight nor fight are viable options for survival (Bracha, 2004). The parasympathetically dominated shutdown of sensory and functional systems reoccurs in confrontation with intrusions, minor stressors or during trauma exposure therapy (for a detailed description of this concept see Schauer & Elbert, 2010).

PTSD commonly co-occurs with depression. In the National Comorbidity Survey, Kessler Sonnega, Bromet, Hughes, and Nelson (1995) found that approximately half of the patients with PTSD had a comorbid major depression. Almost 80% of those patients reported that depression symptoms followed PTSD. In contrast, patients who reported depression prior to trauma exposure reported a higher PTSD symptom severity in response to a single

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event, challenging the direction of comorbidity (Shalev et al., 1998). There is a documented relationship between the number of traumatizing events to which an individual has been exposed and the likelihood of developing PTSD (Neuner et al., 2004).

In sum, PTSD, depression, dissociation and the number of traumatizing events seem to be intercorrelated. The present study utilized a path-analytic approach to disentangle partial relationships, modelling depression as a consequence of PTSD. A sample of women from a war-torn area was chosen because the exposure to traumatic stressors is variable, and rape necessarily implies maximal proximity to the perpetrator, and thus would favour later shutdown dissociation (Schauer & Elbert, 2010).

2.3 Method

2.3.1 Settings and Procedure

Respondents were survivors of the ongoing organised violence in the Eastern Congo who sought medical treatment for gynaecological problems secondary to sexual violence (va- ginal infection or Fistula) at one of the health centres (Panzi Hospital, SOSAME psychiatric centre in Bukavu and health centre Bunjakiri). Six clinical psychologists and one psychiatric nurse from the University of Konstanz carried out interviews between January and March 2009. Prior to assessment the interviewers, who all had prior work experiences in crisis re- gions had been specifically trained.

Respondents were informed about the goal of the study and that they would not re- ceive any financial remuneration for their participation. Respondents were randomly selected from a list of survivors of organised violence provided by the hospitals’ stuff. Everyone who was asked agreed and gave the informed consent. Under-aged participants as well as their legal representatives also signed the form. The University of Konstanz’s ethics committee approved the protocol. Our group trained the personnel of the respective clinical units to provide trauma-focussed treatment. Respondents were referred to these experts and further treatment was supervised.

2.3.2 Instruments

The structured interviews lasted approximately 2.5 hours and were carried out in Eng- lish with the help of trained local translators in Swaheli or Mashi.

To assess shutdown dissociation we used a newly developed 12-item questionnaire based on our concept of shutdown dissociation (Schauer & Elbert, 2010), adapted to the re-

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Female Dissociative Responding 25

spective cultural context. We asked for the frequency of fainting, transitory deafness, changed acoustic perception, transitory blindness, changed visual perception, numbness, transitory paralysis, analgesia, tension, feeling of nausea, out-of-body experiences, and inability to speak. Responses to all items were given on a scale ranging from 0 = not at all, 1 = once a week or less, 2 = 2-4 times a week, to 3 = 5 or more times a week. Factor analysis provided evidence for unidimensionality. The questionnaire showed sufficient internal consistency;

Cronbach’s alpha = .75.

To assess the trauma exposure we used a newly developed checklist consisting of traumatizing events with focus on different experiences of sexual violence. We assessed the number of different traumatic event types that were self-experienced and the number of traumatic event types that were witnessed. A traumatic event type was judged as self- experienced if the participant was the victim and as witnessed if the participant had observed the traumatic event while someone else was threatened.

For the PTSD diagnosis and score, we used the PSS-I (PTSD-Symptom-Scale- Interview), which follows the DSM-IV. The PSS-I has high reliability and validity and is comparable to more complex instruments for diagnosing PTSD (Foa & Tolin, 2000). In order to assess depression symptoms, we used the depression part of the Hopkins-Symptom- Checklist-25 (HSCL-25). This scale demonstrated satisfactory psychometric properties (Glass, Allan, Uhlenhut, Kimball & Borinstein, 1978). Apart from the shutdown dissociation questionnaire, all protocols were tested for their usability and validity in resource-poor settings (Ertl et al., 2010). Moreover, we had extensive discussions about the instruments with local psychologists and medical doctors prior to the assessment.

2.3.3 Data Analysis

Analyses were performed using SPSS 17.0; alpha level was set at .05 and two-sided t- tests were used to analyse significance. Scores with missing data were partially excluded from further analysis (n = 3). We used forced-entry linear regression analysis to evaluate direct and indirect effects on PTSD and depression. In order to constrain the paths in the model, the directions were predetermined by the theoretical assumptions and temporal pre- cedence. Therefore shutdown dissociation, the number of self-experienced and witnessed traumatizing events were considered antecedent to PTSD. Again, shutdown dissociation, the number of self-experienced and witnessed traumatic event types and PTSD, were modelled to predict depression. Associations among variables were taken into account. This model pos-

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its that depressive symptoms in this sample arise primarily as a result of trauma exposure and as a consequence of PTSD.

2.3.4 Participants

The age of the 53 female respondents ranged from 14 to 56 years (mean = 30.0, SD = 11.3). Twenty-one of these survivors were currently married, 10 divorced, 4 widowed and 18 were single (never married). On average, they had two children (range 0 to 11). The educa- tional level varied widely among respondents with a range of 0 to 12 years of education com- pleted. Twenty-nine of the women were illiterate.

2.4 Results

On average, the respondents had experienced 6.9 (range 2 to 15) traumatic events and witnessed 5.5 traumatic events (range 0 to 11). The following self-experienced events were reported most frequently: sexual assault (96.2%), natural disaster (62.3%) and abduction (60.4%). The majority witnessed physical assaults (73.6%), 69.8% witnessed armed assault and 62.3% homicide. The time elapsed since the worst event was variable (Mdn = 3 years;

IQR = 4). Thirty-seven respondents fulfilled all criteria for PTSD (for diagnosis criteria see Foa, Riggs, Dancu & Rothbaum, 1993). Approximately 67% of respondents with and 32%

of those without PTSD met the DSM-IV criteria for depression (Bolton, Neugebauer &

Ndogoni, 2002). The reported PTSD severity (M = 21.40, SD = 8.81) and HSCL-depression score (M = 2.51, SD = 0.64; n = 51) were high. On average, respondents reported a mean sum-score of shutdown dissociation of 8.48 (SD = 6.31).

Guided by theoretical assumptions and previous empirical research on the effects of cumulative trauma and dissociation, we built a path-model to uncover potential associations between the variables. Linear regression coefficients were used as path-coefficients. Shut- down dissociation, the number of self-experienced and witnessed traumatizing events were modelled as being correlated and having both direct and indirect influence on PTSD and depression. Figure 2.1 illustrates the results, with standardized linear regression coefficients.

Model-I indicated two paths to PTSD. Shutdown dissociation and the number of self- experienced traumatic event types influenced PTSD severity. Sufficient power was obtained for the shutdown dissociation, whereas the power of the number of self-experienced event types turned out to be less than .8 (compare Cohen, 1992). The number of witnessed event types was indirectly related to PTSD via the correlation with the number of self-experienced

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traumatizing events (r = .53, p < .001). Table 2.1 provides linear regression coefficients, and respective significance levels.

Model-II proposes two pathways to depression. One path included the PTSD severity. Moreover, PTSD served as a mediator between dissociation and depression. The second path to depression comprised the number of witnessed traumatizing event types. In this model, both variables achieved satisfactory power. Taken together, the analysis revealed an adjusted R² value of .42 in model-I and .43 in model-II.

Table 2.1. Summary of Simultaneous Regression Analyses

Table 2.1a

Summary of Simultaneous Regression Analysis for Variables Predicting PTSD Symptom Severity (N=52)

Model 1 B SE B ß t

constant 1.62 3.59 0.45

shutdown dissociation 0.76 0.15 .56 5.01***

number of traumatic event types self-experienced

0.80 0.37 .28 2.19*

number of traumatic event types witnessed

-0.28 0.38 -.09 -0.74

Note. Unstandardized (B) and standardized (ß) regression coefficients. *p < .05, **p < .001.

Table 2.1b

Summary of Simultaneous Regression Analysis for Variables Predicting Depression Score (N=50)

Model 2 B SE B ß t

constant 1.19 0.27 4.39***

shutdown dissociation 0.01 0.01 .11 0.80

number of traumatic event types self-experienced

-0.06 0.03 -.26 -1.97

number of traumatic event types witnessed

0.08 0.03 .37 2.95*

PTSD symptom score 0.05 0.01 .63 4.47***

Note. Unstandardized (B) and standardized (ß) regression coefficients. *p < .05, **p < .001.

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Figure 2.1: This figure presents a path analytic model for developing PTSD and depression symptoms after traumatizing events and demonstrates one possible model among others. The values in the model are standardized linear regression coefficients. In order to constrain the number of paths in the model, effects between variables that did not reach conventional levels of significance (p > .05) were deleted.

2.5 Discussion

We used a path-analytic approach to examine relationships between the exposure to traumatizing events, shutdown dissociation, PTSD and depression, modelling (for this sample) depression as a consequence of PTSD. Consistent with many other studies, the number of self-experienced traumatizing events significantly predicted the severity of PTSD (Neuner et al., 2004). However, prior studies did not consider witnessed and self-experienced traumatizing events together in a composite model. Surprisingly, witnessing the trauma of others had no direct effect in our model, but seemed to be associated with PTSD via the number of self-experienced traumatizing events.

The second path to PTSD leads through shutdown dissociation. These results are in line with those of Briere and co-workers (2005), who reported that dissociation in the aftermath of the trauma predicts PTSD. Additionally it is consistent with the findings of Nijen- huis, van der Hart, Kruger and Steele (2004), who found a high correlation between somatoform dissociation and PTSD. In addition to the effect of cumulative exposure to traumatizing events, participants who suffered more from shutdown dissociation reported a higher PTSD score. On the one hand, PTSD symptoms can co-occur with shutdown dissociation. Re- experiencing the trauma could evoke the same defensive responses as during the trauma, and reported dissociative responding seems to be more common in participants who experienced

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sexual assaults (Griffin, Resick & Mechanic, 1997). On the other hand, it has been argued that shutdown dissociation may be conditioned as a defensive response to cope with stressful PTSD symptoms (Schauer & Elbert, 2010).

PTSD symptom severity had the highest common variance with depression. This finding argues for co-morbidity. In predicting depression, witnessing traumatizing events seems to play an essential role. Many studies have found a positive relationship between depression and trauma exposure (Monroe & Reid, 2009).

Methodological limitations of this study include the limited sample size. However, even when this is taken into account, shutdown dissociation was still a powerful predictor of PTSD. These results were obtained for female survivors of a war-torn area, who experienced extreme sexual violence and may be, in part specific for this setting. Moreover, the cross- sectional as well as retrospective nature of this study limits attributions about the direction of causality and this path-model represents one possibility for interpreting these results and prospective studies are necessary to provide further support for this outcome. Finally, the newly developed structured interview that we used to measure shutdown dissociation has not yet been validated and inter-reliability wasn’t examined.

We conclude that present observations emphasize the relevance of shutdown dissociation for predicting PTSD. Moreover, the findings suggest differential effects of threat to oneself as opposed to witnessing trauma.

2.6 Acknowledgements

We thank the respondents who participated in the study with great effort and openness. The authors thank the translators Aline Iragi, Benedict Bashimbe, Francine Nsindabagoma, Priska Cinogerwo and Roger Buhendwa from Bukavu and Anna Mädl, Anett Pfeiffer, Elisabeth Schauer, Heike Riedke and Nina Winkler for supporting the interviews. Funded by the Deutsche Forschungsgemeinschaft (DFG) and the European Refugee Fund.

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3. Cardiac Defense in Response to Imminent Threat in Women with Mul- tiple Trauma and Severe PTSD

3.1 Abstract

Posttraumatic stress disorder (PTSD) arises as a long-term result of exposure to trauma and brings with it an altered autonomic response to potentially threatening stimuli. The present study investigates the dynamic sequence of cardiac defense in women with and without PTSD. An acoustic noise of 0.5 s duration and 105 dB was used to elicit the cardiac defense reaction. The stimulus was repeated three times. Within the PTSD sample, respondents who suffered from more severe PTSD showed a higher heart rate at rest, a higher baseline and a greater response. Compared to the healthy subjects, the PTSD group showed an elevated heart rate from 6 s to 25 s following the presentation of the first stimulus. There was evidence of habituation in the PTSD group and hints of differential effects on the cardiac defense of traumatic experiences with a high proximity of danger.

3.2 Introduction

Larger startle responses are a robust physiological correlate of posttraumatic stress disorder (PTSD) (Pole, 2007). Many of the initial studies in this area examined male survivors of trauma related to military service (e.g., Blanchard, Kolb, Pallmeyer & Gerardi, 1982).

Exaggerated startle has also been found in samples of female nurse veterans and survivors of sexual assault (Carson et al., 2007; Metzger et al., 1999; Rothbaum, Kozak, Foa & Whitaker, 2001). The etiology of the elevated level of startle responses is still uncertain. Increased physiological reactivity may reflect a pre-traumatic tendency to higher responses (Guthrie &

Bryant, 2005) or may develop as a kind of posttraumatic neuronal sensitization in parallel with PTSD (Shalev et al., 2000). Another theory states that the anticipatory stressful chal- lenges that the subject underwent trigger the fear network and drive the organism to stronger reactivity (Elbert, Rockstroh, Kolassa, Schauer & Neuner, 2006). In contrast to the literature that shows increased physiological reactivity, there is also conflicting evidence of attenuated psychophysiological response in female respondents who suffer from PTSD. Griffin, Resick and Mechanic (1997) examined a group of sexual assault survivors and found that those subjects with high peritraumatic dissociation exhibited lower heart rate and skin conductance when they were talking about their traumatic experiences. Further studies found evidence that ongoing traumatic stressors such as family violence were correlated with reduced startle reactivity in adult women (Medina, Mejia, Schell, Dawson & Margolin, 2001). Other authors

Psychophysiology of the Defense Cascade and its Relation to Posttraumatic Stress Disorder