Somatoform Dissociative Symptoms Research Articles

Somatoform Dissociative Symptoms Have No Impact on the Outcome of Trauma-Focused Treatment for Severe PTSD

For patients with complex or other severe forms of PTSD, particularly in cases with dissociative symptoms, different treatment approaches have been suggested. However, the influence of somatoform dissociation on the effectiveness of trauma-focused treatment has hardly ever been studied. This study aims to test the hypotheses that (1) PTSD patients reporting a low level and those reporting a high level of somatoform dissociative symptoms would both benefit from an intensive trauma-focused treatment, and that (2) somatoform dissociative symptoms would alleviate. Participants were 220 patients with severe PTSD, enrolled in an intensive treatment program combining EMDR therapy and prolonged exposure therapy, without a preceding stabilization phase. Trauma history was diversified, and comorbidity was high. PTSD symptoms (CAPS-5 and PCL-5) and somatoform dissociative symptoms (SDQ-5 and SDQ-20) were assessed at pre-treatment, post-treatment and at six months after completion of treatment. The course of both PTSD and somatoform dissociative symptoms was compared for individuals reporting low and for those reporting high levels of somatoform dissociative symptoms. Large effect sizes were observed regarding PTSD symptoms reduction for patients with both low and high levels of somatoform dissociation. Somatoform dissociation did not impact improvement in terms of PTSD symptom reduction. The severity of somatoform dissociative symptoms decreased significantly in both groups. This decrease was greater for those with a positive screen for a dissociative disorder. These results add further support to the notion that the presence of strong somatoform dissociative symptoms in patients with PTSD does not necessarily call for a different treatment approach. Clinical implications are discussed.

Psychosocial stress, somatoform dissociative symptoms and free testosterone in premature ejaculation.

One of the most common sexual dysfunctional diseases in adult males is premature ejaculation. So far, there is no evidence of how premature ejaculation is associated with psychosocial stress. We tested the relationship between neuroendocrine changes in patients with premature ejaculation and indicators of stress experience as a new psychosomatic hypothesis where psychosocial stress may significantly contribute to the aetiology of premature ejaculation. A total of 55 patients with premature ejaculation were included in the study. The control group consisted of 55 healthy men. The diagnosis of premature ejaculation was confirmed by a sexology examination, a history of patients and the values of the premature ejaculation diagnostic tool questionnaire. Comprehensive biochemical serum analysis was focused on the values of total testosterone, free testosterone, luteinising hormone, thyroid-stimulating hormone, dehydroepiandrosterone sulphate, sex hormone-binding globulin and a premature ejaculation diagnostic tool score with trauma symptom checklist and somatoform dissociation questionnaire. The results show significant Spearman correlations of trauma symptom checklist with the premature ejaculation diagnostic tool score (R=0.84) and free testosterone (R=0.62) and somatoform dissociation questionnaire with the premature ejaculation diagnostic tool score (R=0.53) and free testosterone (R=0.57). Spearman correlations of trauma symptom checklist with somatoform dissociation questionnaire show significant correlation (R=0.54).

The impact of adverse childhood experience on symptom severity in patients with functional neurological symptom disorder (FNSD)

Theoretical backgroundAdverse childhood experiences (ACE), especially traumatic ACE have been assumed to play a particular role for patients with functional neurological symptoms (FNS): Emotional responses to traumata hypothetically affect (or ‘convert’ into) bodily symptoms. The present study examined this hypothesis scrutinizing the specific impact of (1) traumatic experiences compared to other adversities such as neglect, (2) early childhood compared to adolescent adverse experiences, (3) on FNS compared to psychological symptoms such as depressive and trauma-related symptoms. MethodsNeglect and abuse experiences during childhood and adolescence were assessed in 82 patients diagnosed with functional neurological symptom disorder (FNSD) and 82 healthy comparison participants (HC) together with self-rated FNS (indexed by somatoform dissociative symptoms, SDQ-20), depressive (BDI) and posttraumatic stress symptoms (PDS). Emotion processing was assessed with the TAS-26, which captures the ability to identify and describe one's own emotions (described as alexithymia), ResultsPatients reported more ACE than HC independent of type and age period, more severe functional neurological symptoms and more alexithymia. Alexithymia mediated not only the relationship between ACE and FNS, but also the relationship between ACE and depressive and ACE and trauma-related symptom severity in cases and controls. ConclusionResults emphasize the impact of neglect and abuse on FNSD, and strengthen the proposed ACE influence on affect regulation with its mediating role for symptom expression in support of the conversion concept. The similar impact of ACE on FNS, depressive and trauma-related symptoms suggest a sensitizing impact of childhood adversities on mental health.

Validity and reliability of the Polish online and pen-and-paper versions of the Somatoform Dissociation Questionnaires (SDQ-20 and PSDQ-5)

PurposeThe main objective of this study was to test the psychometric properties of the Polish version of SDQ-20 and the capacity of this instrument, alongside a set of five questions derived from it (SDQ-5), to screen for dissociative disorders. The Somatoform Dissociation Questionnaire (SDQ-20) has been used in many language versions to evaluate the severity of somatoform dissociative symptoms, but no such tool has existed in Polish. Basic proceduresBoth pen-and-paper (p&p) and online versions of SDQ-20 were tested. Validity and reliability were examined in a sample of 597 participants in non-clinical (n=323) and clinical (n=274) groups, who completed the tests p&p (n=79) or online (n=518). The mixed-clinical group included 20 patients diagnosed with dissociative (conversion) disorders using TADS-I, and people with other disorders. Main findingsThe Exploratory Factor Analysis with Principal Component Analysis method of parameter estimation without rotation confirmed unidimensionality of p&p and online versions of SDQ-20. Psychometric properties of the original SDQ-5 were unsatisfactory. Subsequently, an alternative version (PSDQ-5) with a different set of questions derived from SDQ-20 was examined. Reliability of both versions was corroborated by a Cronbach's alpha coefficient (SDQ-20>0.84, PSDQ-5>0.74). The cut-off score maximising sensitivity and specificity was 29.5 (SDQ-20) and 7.5 (PSDQ-5) for dissociative (conversion) disorders (SDQ-20: sensitivity of 95.0% and specificity of 75.6%; PSDQ-5: sensitivity of 95.0% and specificity of 65.9%). People with dissociative disorders had significantly (P<0.001) higher scores in SDQ-20 and PSDQ-5 than patients with other disorders and non-clinical participants (criterion validity). PrincipalConclusion SDQ-20, administered p&p or online, proved to be a reliable tool for the screening of dissociative disorders in Poland. An alternative set of five questions (PSDQ-5) derived from the main instrument also presented good psychometric properties.

Kadın fibromiyalji hastalarında çocukluk çağı travmaları, disosiyatif yaşantılar ve depresyonun ağrı ile ilişkisi: Kesitsel bir çalışma

Objective: The aim of this study was to investigate childhood trauma (CT) and dissociative symptoms in patients with fibromyalgia and evaluate the relationship of these characteristics with pain intensity. Methods: Forty patients followed up with fibromyalgia diagnosis in the physical therapy and rehabilitation outpatient clinic; and as a control group, 38 healthy individuals who have similar age, gender, and educational status, were included in the study. A sociodemographic and clinical data form, Beck Depression Inventory (BDI), Childhood Trauma Questionnaire (CTQ), Dissociative Experiences Scale (DES), Somatoform Dissociation Questionnaire (SDQ) and Visual Analogue Scale (VAS) were administered to participants. Results: Emotional abuse, physical neglect, physical abuse, CTQ total, SDQ and DES scores were found to be significantly higher in the fibromyalgia group than the control group. Only the difference for SDQ scores remained significant when a comparison made between groups by controlling depression levels. Somatoform dissociation scores were found to be a significant predictor of pain intensity in patients with fibromyalgia. Conclusion: Somatoform dissociative symptoms are found to be higher in patients with fibromyalgia than the control group. These symptoms may contribute to development and exacerbation of pain in fibromyalgia. Taking the dissociative symptoms into account have an important role in the treatment of patients with fibromyalgia who have a frequent history of CT, so the treatment of these patients should be carried out in cooperation with psychiatrists.

Dissociation in patients with dissociative seizures: relationships with trauma and seizure symptoms.

This study aimed to extend the current understanding of dissociative symptoms experienced by patients with dissociative (psychogenic, non-epileptic) seizures (DS), including psychological and somatoform types of symptomatology. An additional aim was to assess possible relationships between dissociation, traumatic experiences, post-traumatic symptoms and seizure manifestations in this group. A total of 40 patients with DS were compared with a healthy control group (n = 43), matched on relevant demographic characteristics. Participants completed several self-report questionnaires, including the Multiscale Dissociation Inventory (MDI), Somatoform Dissociation Questionnaire-20, Traumatic Experiences Checklist and the Post-Traumatic Diagnostic Scale. Measures of seizure symptoms and current emotional distress (Hospital Anxiety and Depression Scale) were also administered. The clinical group reported significantly more psychological and somatoform dissociative symptoms, trauma, perceived impact of trauma, and post-traumatic symptoms than controls. Some dissociative symptoms (i.e. MDI disengagement, MDI depersonalization, MDI derealization, MDI memory disturbance, and somatoform dissociation scores) were elevated even after controlling for emotional distress; MDI depersonalization scores correlated positively with trauma scores while seizure symptoms correlated with MDI depersonalization, derealization and identity dissociation scores. Exploratory analyses indicated that somatoform dissociation specifically mediated the relationship between reported sexual abuse and DS diagnosis, along with depressive symptoms. A range of psychological and somatoform dissociative symptoms, traumatic experiences and post-traumatic symptoms are elevated in patients with DS relative to healthy controls, and seem related to seizure manifestations. Further studies are needed to explore peri-ictal dissociative experiences in more detail.

Emotion regulation strategies in trauma-related disorders: pathways linking neurobiology and clinical manifestations

Emotion regulation impairments with traumatic origins have mainly been studied from posttraumatic stress disorder (PTSD) models by studying cases of adult onset and single-incident trauma exposure. The effects of adverse traumatic experiences, however, go beyond the PTSD. Different authors have proposed that PTSD, borderline personality, dissociative, conversive and somatoform disorders constitute a full spectrum of trauma-related conditions. Therefore, a comprehensive review of the neurobiological findings covering this posttraumatic spectrum is needed in order to develop an all-encompassing model for trauma-related disorders with emotion regulation at its center. The present review has sought to link neurobiology findings concerning cortico-limbic function to the field of emotion regulation. In so doing, trauma-related disorders have been placed in a continuum between under- and over-regulation of affect strategies. Under-regulation of affect was predominant in borderline personality disorder, PTSD with re-experiencing symptoms and positive psychoform and somatoform dissociative symptoms. Over-regulation of affect was more prevalent in somatoform disorders and pathologies characterized by negative psychoform and somatoform symptoms. Throughout this continuum, different combinations between under- and over-regulation of affect strategies were also found.

Traumatic Experience and Somatoform Dissociation Among Spirit Possession Practitioners in the Dominican Republic.

Recent studies in African contexts have revealed a strong association between spirit possession and severe trauma, with inclusion into a possession cult serving at times a therapeutic function. Research on spirit possession in the Dominican Republic has so far not included quantitative studies of trauma and dissociation. This study evaluated demographic variables, somatoform dissociative symptoms, and potentially traumatizing events in the Dominican Republic with a group of Vodou practitioners that either do or do not experience spirit possession. Inter-group comparisons revealed that in contrast to non-possessed participants (n = 38), those experiencing spirit possession (n = 47) reported greater somatoform dissociation, more problems with sleep, and previous exposure to mortal danger such as assaults, accidents, or diseases. The two groups did not differ significantly in other types of trauma. The best predictor variable for group classification was somatoform dissociation, although those items could also reflect the experience of followers during a possession episode. A factor analysis across variables resulted in three factors: having to take responsibility early on in life and taking on a professional spiritual role; traumatic events and pain; and distress/dissociation. In comparison with the non-possessed individuals, the possessed ones did not seem to overall have a remarkably more severe story of trauma and seemed to derive economic gains from possession practice.

DSM–5’s Posttraumatic Stress Disorder with Dissociative Symptoms: Challenges and Future Directions

The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, formally recognizes a dissociative subtype of posttraumatic stress disorder (PTSD; PTSD with dissociative symptoms). This nomenclative move will boost empirical and theoretical efforts to further understand the links between dissociation, trauma, and PTSD. This article examines the empirical literature showing that patients with PTSD can be divided into 2 different groups based on their neurobiology, psychological symptom profile, history of exposure to early relational trauma, and depersonalization/derealization symptoms. It then explores the conceptual and empirical challenges of conceiving 1 of these types as reflecting a “dissociative” type of PTSD. First, this classification is based on the presence of a limited subset of dissociative symptoms (i.e., depersonalization, derealization). This sets aside an array of positive and negative psychoform and somatoform dissociative symptoms that may be related to PTSD. Second, empirical evidence suggests heightened dissociation in PTSD compared to many other disorders, indicating that dissociation is relevant to PTSD more broadly rather than simply to the so-called dissociative subtype. This article sets out important issues to be examined in the future study of dissociation in PTSD, which needs to be informed by solid conceptual understandings of dissociation.

Early Traumatized Inpatients High in Psychoform and Somatoform Dissociation: Characteristics and Treatment Response

This study examined the clinical relevance of differences in psychoform and somatoform dissociative symptoms in 55 early traumatized inpatients. The high psychoform and somatoform dissociative group (n = 18), somatoform dissociative group (n = 22), and nondissociative group (n = 15) did not differ on abuse severity, depressive symptoms, interpersonal problems, Axis I or II comorbidity, or deterioration rates. Compared to the other 2 groups, the highly dissociative group was characterized by younger age, living alone, higher levels of posttraumatic and general distress, more frequent reports of suicidality, self-mutilation, eating problems, and less favorable treatment response. The results highlight the clinical relevance of using dissociation measures for identifying subgroups of patients with severe psychopathology who may be more treatment resistant.

The Association Among Childhood Maltreatment, Somatic Symptom Intensity, Depression, and Somatoform Dissociative Symptoms in Patients with Fibromyalgia Syndrome: A Single-Center Cohort Study

Research demonstrates strong associations between childhood maltreatment and health problems that include dissociative symptoms and fibromyalgia syndrome (FMS). We assessed the associations among childhood maltreatment, somatic symptom severity, depression, and somatoform dissociative symptoms in all consecutive adult FMS patients of a tertiary referral pain medicine center between January 2010 and December 2011. Childhood maltreatment was assessed with the Childhood Trauma Questionnaire, somatoform dissociative symptoms with the Somatoform Dissociation Questionnaire, somatic symptom severity with the Patient Health Questionnaire–15 and depression by the Patient Health Questionnaire–2. A total of 117 patients (84% women) were included in the analysis, of whom 20.5% reported severe emotional abuse, 8.6% severe physical abuse, 12.8% severe sexual abuse, 25.6% severe emotional neglect, and 12.0% severe physical neglect in childhood and adolescence. On average, patients reported high levels of somatoform dissociative symptoms and moderate levels of somatic symptom severity and depression. Somatoform dissociative symptoms and emotional abuse were moderately correlated (r = .32). In hierarchical regression analysis, gender (p = .01) and somatic symptom severity (p < .0001) but not childhood maltreatment and depression were significant predictors of somatoform dissociative symptoms. Reports of somatoform dissociative symptoms by FMS patients might be attributed to their tendency to report multiple somatic symptoms.

P-473 - Oxytocin reflects levels of trauma-related and dissociative symptoms in patients with severe depression

Introduction Recent findings suggest that functional irregularities in oxytocin biology may play a role in the pathophysiology of depression. One of the proposed pathways is related to stress, as oxytocin exerts a regulatory effect over neuroendocrine stress axis. Moreover, stress exposure and stress axis dysregulation are likely connected to dissociative symptoms. Objectives Therefore, the study investigates the relationship between depression severity, stress symptoms levels, dissociation and plasma oxytocin levels. Methods Depression severity was assessed by Beck Depression Inventory (BDI-II), symptoms related to stress were assessed by Trauma Symptom Checklist (TSC-40), psychological and somatoform dissociative symptoms were assessed by Dissociative Experiences Scale (DES) and Somatoform Dissociation Questionnaire (SDQ-20), respectively. Plasma oxytocin was measured using radioimmunoassays. Results 69 patients were included in the study, 34 in severe depression group (BDI-II≥29) and 35 in mild to moderate depression group (BDI-II≤28). The groups did not differ significantly in oxytocin levels. In severe depression group, negative correlations between oxytocin and TSC-40 and SDQ-20 were found (R = −0,55; p Conclusion The negative correlation between oxytocin and symptoms related to trauma and somatoform dissociation in severe depression group is, to our knowledge, the first finding in this context. It is consistent with stress-reducing effect of oxytocin in acute stress paradigms and suggests that stress and somatoform dissociation may represent important factors in complex relationship linking oxytocin to depression. The directionality of these relationships need to be assessed in longitudinal studies.

The Validity and Reliability of the German Version of the Somatoform Dissociation Questionnaire (SDQ-20)

The present study investigated the validity of the German version of the Somatoform Dissociation Questionnaire (SDQ-20), a scale designed to measure somatoform dissociative symptoms. Somatoform dissociation involves physical manifestations of a dissociation of the personality and is considered a unique entity in the phenomenological spectrum of dissociation. The validity and reliability of the German version of the SDQ-20 was examined using a sample of 225 patients with (n = 39) and without dissociative disorders who were recruited from several in- and outpatient psychiatric clinics. Patients were assessed using structured diagnostic interviews; diagnostic checklists; and self-rating scales for dissociation, and posttraumatic stress. Patients with dissociative disorders reported significantly more (p < .001) somatoform dissociative symptoms than patients without dissociative disorders (criterion validity). Significant correlations (p < .001) were found between scores of somatoform dissociation, psychoform dissociation, posttraumatic stress symptoms, and traumatic childhood experiences (construct validity). Reliability was corroborated by a Cronbach's alpha coefficient of .91 and a test–retest correlation of .89. A component factor analysis suggested unidimensionality of the SDQ-20. In conclusion, the psychometric properties and cross-cultural validity of the German version of the SDQ-20 are excellent. Our results form the basis for the further study of somatoform dissociation in German-speaking populations.

Somatoform Dissociation and Symptoms of Traumatic Stress in Adolescents

Abstract Dissociation is traditionally attributed to trauma and other psychological stressors although there is evidence that in many cases dissociative symptoms could be attributable to initial brain insult, injury or other organic brain disease. With respect to these findings there is a question to which extent symptoms of somatoform dissociation are related to symptoms of traumatic stress or whether these symptoms may be predominantly attributed to various somatic factors. With this aim we have assessed the relationship between somatoform dissociation and symptoms of traumatic stress in a group of 75 healthy adolescents. Main result of this study indicates statistically significant relationship between somatoform dissociative symptoms and psychosocial stressors measured by symptoms of traumatic stress. Results of this study also show that the symptoms of somatoform dissociation may occur continuously in population and that only in high level of their experience they cause psychopathological states. In this context, result of this study suggests that also mild levels of stress influence somatic feelings that may lead to symptoms that may occur also as a consequence of various somatic factors.

The Scoring and Interpretation of the SDQ-20 and SDQ-5

Abstract The 20-item Somatoform Dissociation Questionnaire (SDQ-20; Nijenhuis, Spinhoven, Van Dyck, Van der Hart, &amp; Van-derlinden, 1996) evaluates the severity of somatoform dissociation. The SDQ-20 items were derived from a pool of 75 items describing clinically observed somatoform dissociative symptoms that in clinical settings had appeared upon reactivation of particular dissociative parts of the personality and that could not be medically explained. The SDQ-20 scores were best predicted by self-reported physical and sexual traumatization in patients with dissociative disorders and psychiatric controls (Nijenhuis et al., 1998c), even after statistically controlling for self-reported emotional traumatization (emotional neglect and emotional abuse). These traumatization scores were composed of four factors, i.e. presence of trauma, duration of trauma, relationship to perpetrator, and subjectively rated impact of trauma.

Illusory touch and tactile perception in somatoform dissociators

Objective The psychological mechanisms of somatoform dissociation (i.e., pseudoneurological symptoms) are poorly understood. This study evaluated recent theoretical predictions regarding the role of tactile perception in the development of somatoform dissociative symptoms. Methods Eighty nonclinical participants scoring either high or low on the Somatoform Dissociation Questionnaire (SDQ-20) completed the Somatic Signal Detection Task (SSDT), a novel perceptual paradigm designed to simulate the occurrence of somatoform symptoms in the laboratory. Prior to the SSDT, participants completed a memory task designed to produce either minimal or maximal activation of tactile representations in memory. Results The high SDQ-20 group exhibited a more liberal response criterion ( c) on the SSDT than the low SDQ-20 group after controlling for negative affectivity, somatosensory amplification and depression. This effect was mainly attributable to an increased number of false alarms (i.e., illusory experiences of touch) in the high SDQ-20 group rather than an increased hit rate. General perceptual ability (i.e., tactile sensitivity) was comparable between the two groups. The memory manipulation had no effect on SSDT performance. Conclusions Somatoform dissociators appear more likely to experience illusory perceptual events under conditions of sensory ambiguity than nondissociators, despite comparable perceptual abilities more generally. These findings support theories that identify distorted perceptual processing as a feature of somatoform dissociation. The SSDT has potential as a tool for further research in this area.

Posttraumatic Somatoform Dissociation in French Psychiatric Outpatients

ABSTRACT Objective: Somatoform dissociative phenomena have long existed in psychiatric nosology but few quantitative data exist. This study aims at substantiating the association between trauma and somatoform dissociation, and presenting elements of validation of the French version of the Somatoform Dissociation Questionnaire (SDQ-20). Indeed, the SDQ-20 is a simple to use self-report questionnaire developed to quantify somatoform dissociative symptoms. Methods: One hundred forty psychiatric outpatients consecutively seen in the University Hospital in Tours, France were included, and completed the SDQ-20, the Dissociative Experiences Scale (DES), an inventory of traumatic experiences, and underwent a structured interview (CAPS) for diagnosis of Posttraumatic Stress Disorder (PTSD) according to the DSM-IV criteria. Results: We found a strong association between the SDQ-20 mean score and current PTSD or past PTSD. The Principal Components Analysis of this French version yielded a solution containing three factors: sensory neglect, subjective reactions to perceptive distortions, and vigilance modulation disturbance. The reliability of this French version was studied through the Cronbach's α coefficient (0.83). Both scales of dissociation used in our study (DES, SDQ-20) were shown to be highly correlated. Conclusion: This study confirms the strong association between trauma and dissociative symptoms as a whole, including somatoform dissociation. The SDQ-20 appeared to be a potentially useful screening instrument for dissociative disorders. It shed light on a “sub-dimension” of the dissociative phenomenon, when expressed in a somatic way.

Somatoform Dissociation

In most of the recent scientific and clinical literature, dissociation has been equated with dissociative amnesia, depersonalization, derealization, and fragmentation of identity. However, according to Pierre Janet and several World War I psychiatrists, dissociation also pertains to a lack of integration of somatoform components of experience, reactions, and functions. Some clinical observations and contemporary studies have supported this view. Somatoform dissociation, which can be measured with the Somatoform Dissociation Questionnaire (SDQ-20), is highly characteristic of dissociative disorder patients, and a core feature in many patients with somatoform disorders and in a subgroup of patients with eating disorders. It is strongly associated with reported trauma among psychiatric patients and patients with chronic pelvic pain presenting in medical healthcare settings. Motor inhibitions and anesthesia/analgesia are somatoform dissociative symptoms that are similar to animal defensive reactions to major threat and injury. Among a wider range of somatoform dissociative symptoms, these particular symptoms are highly characteristic of patients with dissociative disorders. The empirical findings reviewed in this article should have implications for the contemporary conceptualization and definition of dissociation, as well as the categorization of somatoform disorders in a future version of the DSM.

Somatoform Dissociation in Traumatized World War I Combat Soldiers

The massive traumatization of World War I combat soldiers led to an unprecedented incidence of somatoform dissociative disorders and symptoms, usually diagnosed as hysterical disorders during the war years. Following a brief overview of the scope of the suffering during this Great War, attention is given to British army psychiatrist Charles S. Myers' (1940) observations of the alternation between a so-called “emotional” personality and an “apparently normal” personality in traumatized combat soldiers. Somatoform dissociation, further categorized into positive and negative symptoms, is related to this structural dissociation, and to fixation in the trauma and avoidance of the trauma, and may be part of a more encompassing symptomatology. Next, a short overview of diagnostic issues is given. We argue that the DSM-IV category of “conversion disorder” is incorrect. Rather, the findings revealed here support Janet's classic and Nijenhuis' more recent views on somatoform dissociation. Finally, treatment issues are briefly presented.

Somatoform dissociative symptoms as related to animal defensive reactions to predatory imminence and injury.

Somatoform dissociative symptoms as related to animal defensive reactions to predatory imminence and injury.