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2003; Griffin, Resick, & Mechanic, 1997; Lanius et al.,. 2002; Williams .... ongoing and frequent or greater life stress have greater car- diovascular .... ate degree.

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C 2004) Journal of Traumatic Stress, Vol. 17, No. 1, February 2004, pp. 47–54 (°

Relationships of Dissociation and Childhood Abuse and Neglect With Heart Rate in Delinquent Adolescents Cheryl Koopman,1,3 Victor Carrion,1 Lisa D. Butler,1 Shiv Sudhakar,2 Laura Palmer,1 and Hans Steiner1

This study examined the relationship of dissociative symptoms, abuse and neglect, and gender to mean heart rate (HR) in two types of interviews. Participants were 25 female and 16 male delinquent adolescents. Dissociative symptoms and abuse and neglect were assessed by structured interviews. Participants were randomized to one of two conditions, to describe either their most stressful life experience or their free association thoughts. Greater dissociative symptoms were associated with lower mean HR, whereas abuse and neglect, being a girl, and participating in the free association task were associated with higher mean HR. The finding that high levels of dissociative symptoms may be related to a suppression of autonomic physiological responses to stress support Bremner’s conceptualization (J. D. Bremner, 1999) that dissociative symptoms comprise one of two subtypes of the acute stress response, differing physiologically as well as subjectively from a predominantly hyperarousal or intrusive symptom response. KEY WORDS: dissociation; heart rate; child abuse; neglect; gender; stress interview.

Heart rate appears to be an important indicator of reactions to traumatic life events, both in predicting traumatic stress response and as a concomitant of the traumatic stress response. Individuals experiencing higher heart rates immediately following a traumatic life event are more likely to develop posttraumatic stress disorder (PTSD; Bryant, Harvey, Guthrie, & Moulds, 2000; Shalev et al., 1998). Furthermore, heart rate responses to reminders of an event have been found to be greater among person who have already developed PTSD, including veterans (Casada, Amdur, Larsen, & Liberzon, 1998; Liberzon, Abelson, Flagel, Raz, & Young, 1999), women sexually abused in childhood (Orr et al., 1997; Orr, Lasko, Metzger, Ahern, & Pitman, 1998), and motor vehicle accident sur-

vivors (Blanchard et al., 1996). Such heart rate responsivity to traumatic life event reminders may exhibit a conditioned emotional response (Orr et al., 1997; Shalev, 1999). Indeed, hyperarousal symptoms are considered so essential to the DSM-IV diagnosis of PTSD that they are required making for this diagnosis. In contrast to evidence that PTSD is associated with higher heart rate responses to reminders of traumatic life events, several studies suggest that dissociative symptoms are associated with lower physiological arousal to such reminders (Delahanty, Royer, Raimonde, & Spoonster, 2003; Griffin, Resick, & Mechanic, 1997; Lanius et al., 2002; Williams, Haines, & Sale, 2003). Griffin et al. (1997) found that women who reported high levels of peritraumatic dissociation at the time of a rape showed lower heart rate levels and skin conductance responses when they were interviewed about their rape within 2 weeks following the event, compared to women who reported less peritraumatic dissociation. Among women with PTSD for sexual abuse, high dissociators showed no increase in heart rate

1 Stanford

University, Stanford, California. University, Durham, North Carolina. 3 To whom correspondence should be addressed at Department of Psychiatry and Behavioral Sciences, Stanford University School of Medicine, Stanford, California 94305-5718; e-mail: [email protected] leland.stanford.edu. 2 Duke

47 C 2004 International Society for Traumatic Stress Studies 0894-9867/04/0200-0047/1 °

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48 in response to recalling a traumatic memory, in contrast to low dissociators (Lanius et al., 2002). A case study of a woman diagnosed with dissociative identity disorder found to decrease dramatically in her heart rate when a traumatic incident was described, which she reported was associated with a depersonalization form of dissociation and which contrasted to her heart rate response to other types of scripts (Williams et al., 2003). A study of men and women admitted to a hospital immediately following motor vehicle accidents found that greater peritraumatic dissociation was inversely associated with two indicators of physiological reactivity, levels of urinary norepinephrine and epinephrine, but not with urinary cortisol or baseline heart rate (Delahanty et al., 2003). Taken together, the findings of previous studies are consistent with an understanding of dissociation as being associated with altered autonomic physiological responses to stressful stimuli. This is particularly interesting because dissociative symptoms are greater among persons with PTSD, as Bremner et al. (1992) first found in a sample of Vietnam combat veterans, despite dissociative symptoms showing inverse relationships with indices of physiological arousal that are positively related to PTSD. Bremner (1999) has suggested that dissociative symptoms may be one of two pathways of response to acute stress, the other one focusing predominantly on hyperarousal or intrusive symptoms. Thus, there may be distinctive physiological patterns associated with dissociation and PTSD as defined in the DSM-IV. A detailed analysis of biological mechanisms related to dissociative symptoms is beyond the scope of this study. A promising framework based on available research has been proposed by Krystal, Bremner, Southwick, and Charney (1998) to suggest that alterations of thalamic activity may play a major role in the experience of dissociative symptoms by disrupting the flow of sensory information to the cortex. Such disruption may allow for the experience of altered states of consciousness by connecting features of hypnosis, dreaming, and other features of the waking and sleeping state that focus on internally generated thought and sensory experiences. Furthermore, findings by Lanius et al. (2002) provide some support for Sierra and Berrios’ “corticolimbic model of depersonalization” (Sierra & Berrios, 1998) in which corticolimbic disconnection occurs in depersonalized states, with medial prefrontal activation accompanied by reciprocal inhibition of the amygdala, which results in decreased arousal and blunted emotionality. This study tested the generalizability of previous research on the relationship of dissociation to physiological arousal, by studying a different population, as well as in the types of dissociation, stressful life events, and stim-

Koopman, Carrion, Butler, Sudhakar, Palmer, and Steiner ulus conditions studied. In contrast to studies comparing changes over time in heart rate following a baseline assessment (Griffin et al., 1997; Williams et al., 2003) this assessed the mean heart rate experienced during an interview. This study also tested the generalizability of previous findings to a new population (i.e., delinquent adolescents rather than adults), to different kinds of dissociative symptoms (i.e., pathological dissociative symptoms vs. peritraumatic dissociative symptoms), and to other kinds of stressors (i.e., childhood abuse and neglect vs. sexual assault or a motor vehicle accident). Testing the generalizability of previous findings suggesting that dissociative symptoms are specifically associated with alterations in physiological responses is important because this knowledge may help to clarify whether dissociative symptoms should be considered a core aspect of acute and posttraumatic stress reactions to traumatic events (see Bryant & Harvey, 2000; Butler, 2000; Koopman, 2000; Marshall, Spitzer, & Liebowitz, 1999; Spiegel, Spiegel, Classen, & Carde˜na, 2000). In this study we hypothesized that lower mean heart rates would be experienced during interviews among delinquent youths who experience greater dissociative symptoms. Furthermore, we sought to examine several other factors in relation to mean heart rate, independent of dissociative symptoms. We hypothesized that higher mean heart rates would be found among those who have endured more abuse and neglect, are girls, or receive stressful event interview instructions as compared to receiving free association instructions. Below we summarize reasons for examining each of these additional hypotheses. The hypothesis that experiencing more abuse and neglect would be associated with a higher mean heart rate was suggested by evidence that persons who have more ongoing and frequent or greater life stress have greater cardiovascular responses to acute stress situations (Lepore, Miles, & Levy, 1997; Matthews, Gump, Block, & Allen, 1997). However, the need for further research is suggested by the inconsistent nature of the available evidence (e.g., Roy, Steptoe, & Kirschbaum, 1998). The hypothesis that girls would experience higher heart rates than boys during the interviews was supported by studies that adolescent girls had higher baseline heart rates (Steiner, Ryst, Berkowitz, Gschwendt, & Koopman, 2002) and that heart rates showed greater increases in girls than boys when they participated in stressful social competency interviews (Allen & Matthews, 1997). Furthermore, among college students, women had higher heart rates when speaking than did men (Tardy & Allen, 1998). However, Steiner et al. (2002) found that boys experienced significantly greater increases in heart rate 5 min into an interview compared to girls, suggesting

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Dissociation, Abuse and Neglect, and Heart Rate research is needed to better understand gender differences in cardioreactivity. We expected that higher mean heart rates would be experienced among adolescents when given instructions to describe their most stressful life event compared to instructions to engage in free association, which was intended to serve as a less stressful interview task. Our expectation that the stressful life event instructions would elicit a higher heart rate was guided by thinking that these instructions would be more likely to elicit reminders of stressful events, which has been found in previous studies to be associated with greater physiological reactivity, especially among those who have developed PTSD (Blanchard et al., 1996; Casada et al., 1998; Orr et al., 1997, 1998). Although this study did not examine PTSD, previous evidence of greater reactivity to trauma reminders could be thought to display an extension of the stress response. We thought that instructions to describe the most stressful life event would elicit the heightened physiological responses previously found to be associated with the posttraumatic stress response to recalling such an event (Casada et al., 1998). Questions about the specificity of heightened arousal responses to reminders of traumatic events are raised by the findings of Kinzie et al. (1998) who found that Cambodian refugees reacted with general nonspecific arousal to a variety of stressful stimuli, not just to a trauma-related scene of a Cambodian refugee camp. Because this study focuses on delinquent adolescents, similar to Cambodian refugees in having experienced much life stress, it seemed important to evaluate heart rate responses to different types of interviews varying in their focus on life stress. Therefore, we compared youths’ responses to instructions to describe their most stressful life event to those to an interview in which they could discuss anything they wanted to, which we expected to be less stressful because it did not dictate that a stressful topic be discussed.

Method

49 a weekend program at the probation center. The appropriate institutional review board approved human participants’ involvement in this study. Informed consent was provided by the responsible court for its ward’s participation in the study, functioning in loco parentis, as the guardian who evaluates nontherapeutic risks as a responsible parent would. The youths’ participation in the study was voluntary, and written informed assent was obtained from all youths. Also, we notified parents of their child’s willingness to participate in the study, and only 1 youth was withdrawn from the larger study because of parental preferences. Youths were included in the study if they met the following criteria: (1) between 11 and 16 years of age; (2) either detained at the juvenile detention hall or attending a weekend community service program as part of a sentence; and (3) able to participate in three consecutive sessions. Youths were excluded due to being psychotic, suicidal, or homicidal because participating in this study could unduly distress them. Youths were excluded who had a history of clinically significant head injury, epilepsy or other neurological disorder, current alcohol or substance dependence, or current use of medications because their data could be affected by these conditions and therefore could render the results less generalizable. Participants were all those for whom we had complete data for the analyses in this study. Four of the initial participants were dropped due to missing data on heart rate due to artifact. Participants ranged from 11 to 16 years of age (M = 14.4, SD = 1.1). Males comprised 39% of the sample. Ethnic background was: 39% Hispanic/Latino, 24% African American, 22% Caucasian, 12% mixed, and 2% other. The highest level of education completed by the participants’ parents ranged as follows: 22.2% completed up to 9th grade, 2.8% attended 10th–12th grade, 33.3% graduated from high school, 8.3% attended some college, 30.6% graduated from college, and 2.8% earned a graduate degree. This sample did not differ significantly in any of the demographic or psychosocial variables from those participants in the original sample with missing data for this study.

Participants Forty-one participants were recruited from a larger study of trauma and dissociation in 65 delinquent adolescents (Carrion & Steiner, 2000). Youths were recruited from the San Mateo County Juvenile Probation Department in California, where they were under court supervision for minor crimes, such as using illegal drugs, and not for major crimes such as homicide. Most of the youths (57/65) were incarcerated from 1 week to 3 months, and 7 youths were living in the community and completing

Measures The Childhood Trauma Interview (CTI; Fink, Bernstein, Handelsman, Fotte, & Lovejoy, 1995), a semistructured interview, was used to assess experiences of childhood abuse and neglect. This assessment focused on physical abuse/assault, sexual abuse\assault, emotional abuse, physical neglect, and emotional neglect. Validity and interrater reliability of this interview have been

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50 demonstrated in adult populations (Fink et al., 1995). A strength of this instrument was that it assessed the intensity of five types of abuse or neglect rather than simply scoring these dichotomously as either absent or present, allowing a more sensitive assessment that included a range of possible intensities. Each type of abuse or neglect was scored as the product of three scores pertaining to that event: severity (scored “0”–“6”); frequency (scored “0”–“6”); and duration (time elapsing from onset to the termination of each type of event). A total score on this measure was obtained by summing these scores across all five types of abuse/ neglect rather than strictly adhering to the more complex scoring procedure described in the scoring manual. The Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D; Steinberg, 1996) used a structured clinical interview format to assess the presence and severity of five dissociative symptoms: amnesia, depersonalization, derealization, identity confusion, and identity alteration. The SCID-D has been shown to have satisfactory reliability and discriminant validity for assessing dissociative disorders (Steinberg, 1996). Furthermore, this measure has been shown in case study research to yield highly similar profiles in adolescents and adults, providing evidence suggesting the validity for assessing dissociative symptoms among adolescents (Steinberg & Steinberg, 1995), although this interview needs to be further evaluated for its reliability and validity for use with adolescents. A number of specific questions were asked about each type of dissociative symptom, and then a global rating was made for each symptom using a 4-point scale in which 1 = absent, 2 = mild, 3 = moderate, and 4 = severe. Because a dissociation total symptom severity score was computed by summing the severity rating of each of the five dissociative symptoms, total symptom severity scores could range from 5 to 20. Mean heart rate. To assess heart rate, we used a pulsatron, a heart-rate monitor that is a magnetic belt worn around the chest that detects heartbeats. The research interviewer, who was blind to this study’s hypotheses, wore a watch that registered the information detected by the belt and translated it into beats sampled during each of the minutes during the course of the 10-min interview period, which the research interviewer manually recorded onto a data sheet. We summed the heart rates for each of the 10 min of the interview and divided the sum by 10 to compute each participant’s mean heart rate.

Procedure The three assessment sessions were conducted within the month after each youth was recruited, with the sessions

Koopman, Carrion, Butler, Sudhakar, Palmer, and Steiner typically spaced about a week apart. Each session lasted from 1 to 2 hr in duration and ended with providing the youth with debriefing. In Session 1, an “Intake Data” sheet was used to record standard demographic characteristics, including age, sex, and ethnic background. In Session 2, the Childhood Trauma Interview and the Structured Clinical Interview for DSM-IV Dissociative Disorders were administered. In Session 3, youths were randomly assigned to one of two types of speech conditions and their mean heart rates were assessed while they spoke. One type of interview, the stressful event interview, asked each youth to describe his or her most stressful life event: “For the next 10 min, I want you to talk about the most upsetting or scary or stressful think that you ever had to go through.” The free association interview asked each youth to describe their thoughts: “For the next 10 min, talk about anything you want to talk about.” Twenty-one participants were randomly assigned to the stressful event interview condition; and 20 participants were randomly assigned to the free association interview condition.

Data Analyses We computed correlation coefficients between gender, the scores on the Childhood Trauma Interview, the total dissociation symptoms score on the SCID-D, and type of interview (free association/stressful event). These results are presented in Table 1. None of these relationships were statistically significant. Mean heart rate was the dependent variable. We adhered to the guideline that 10 participants are required for each independent variable tested in the primary analysis, and so 41 participants in our sample with complete data limited our analysis to four independent variables. We used a simultaneous entry procedure of the variables because we had identified specific a priori hypotheses that we wanted to test in an overall model. We also examined for possible differences between the interview task conditions on demographic variables and the independent variables examined in this study to evaluate the effectiveness of randomization to interview condition. Because we depended upon randomization to try to even out differences between the two interview conditions, we needed to evaluate the success of randomization in this regard. Chi-square tests were used to examine for possible differences in the categorical variables (i.e., gender and ethnicity), and t tests for independent groups were used to evaluate differences in the continuous variables (e.g., age, SCID-D score, and CTI score).

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Dissociation, Abuse and Neglect, and Heart Rate

51

Table 1. Pearson Correlation Coefficients Examining the Relationships Among Gender, Childhood Trauma Interview Score, SCID-Dissociation Score, Type of Interview, and Mean Heart Rate Variable

Gender

CTI total score

SCID-Dissociation score

Type of interview

CTI total score SCID-Dissociation score Type of interviewb Mean heart rate per minute

— .24 .10 −.18 .40∗

— .12 .07 .31∗

— −.18 −.20

— −.28

Gendera

Note. CTI = Childhood Trauma Interview.

a 1 = boy; 2 = girl. b 1 = free association; ∗ p < .05.

2 = stressful event interview.

Results The total scores on the Childhood Trauma Interview ranged from 1 to 1011 (M = 251.9, SD = 201.0). SCID-D dissociation symptoms total severity scores ranged from 5 to 19 (M = 8.5, SD = 3.2), with 7 (17.1%) of youths who scored a 5 and therefore reported no dissociative symptoms; 23 (56.1%) of youths who scored between 6 and 9 and therefore were considered mild to moderate in their dissociative symptoms; and 11 (26.8%) of youths who scored from 10 to 20 and therefore were considered severely affected with dissociative symptoms. Mean heart rate during the free association speech task ranged from 62.0 to 97.4 beats/min (M = 85.5, SD = 8.5) and during the stressful event interview ranged from 62.0 to 99.3 beats/min (M = 80.2, SD = 10.4). Table 1 presents the correlation coefficients among the independent variables (gender, SCID-D total scores, CTI scores, and instructional condition). We also found that gender was fairly independent of the specific types of abuse and neglect, as shown by results in which emotional abuse was the only type of abuse/neglect showing a significant gender difference, with girls reporting significantly more emotional abuse than did the boys, t(30) = −2.05, p < .05, two-tailed. Table 2 presents the results of the simultaneous multiple regression on mean heart rate. Dissociative symptoms, abuse and neglect, gender, and type of interview were all significantly related to mean heart rate, F(4, 36) = 5.01, p < .01, overall adjusted R 2 = .29. As predicted, persons with higher SCID-D dissociation scores tended to have lower heart rates ( p < .05). Also consistent with our hypotheses, mean heart rate was found to be greater among those who reported having experienced more abuse and neglect ( p < .05) and who were girls ( p < .05). Type of interview was also significantly associated with mean heart rate, but in the opposite direction from what was hypothesized. Higher mean heart rate was associated with participating in the free association condition rather than

the stressful event condition ( p < .05). No significant difference between the groups randomized to the two types of interview was found in gender, ethnicity, mean age, SCID-D score, or CTI score. A secondary multiple regression analysis did not show age or any of the ethnicity dummy variables to be significantly associated with mean heart rate. For the other independent variables in the model, the results remained identical to those described above for the primary regression analysis. In an exploratory analysis to try to identify which, if any, of the dissociative symptoms were particularly associated with lower heart rate, we computed Pearson’s correlation coefficients between mean heart rate and scores for each of five types of dissociative symptoms. Mean heart rate was significantly and negatively related to derealization, r = −.29, p < .05, and identity alteration, r = −.33, p < .05, but not to amnesia, depersonalization, or identity confusion. We used a similar exploratory analysis to try to identify which, if any, of the types of abuse or neglect was specifically associated with higher heart rate. Higher mean heart rate was significantly associated with experiencing greater physical neglect, r = .28, p < .05, and emotional abuse, r = .30, p < .05, but not with physical or sexual abuse nor emotional neglect.

Table 2. Results of the Multiple Regression Analysis of Mean Heart Rate Analyzed by Delinquent Adolescents’ Gender, SCID-Dissociation Score, Childhood Trauma Interview Score, and Type of Interview Independent variable

B

SE B

β

Intercept Gender Childhood Trauma Interview SCID-Dissociation score Type of interviewa

86.53∗∗ 6.00∗ 0.01∗ −0.98∗

7.58 2.77 0.01 0.42 2.68

— .30 .29 −.32 −.30

−5.73

Note. Overall model F(4, 36) = 5.01, p < .01, overall adjusted R 2 = .29. a 1 = free association; 2 = stressful event interview. ∗ p < .05. ∗∗ p < .01.

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52 Discussion Freud and Breuer are credited with developing the notion that dissociation serves as a defense against anxiety (Nemiah, 1998), and considerable research has documented its association with traumatic experience (reviewed in Butler, Dur´an, Jasiukaitus, Koopman, & Spiegel, 1996). Until recently, this idea was supported primarily by clinical observations rather than objective biological measures. The present study finds that among delinquent adolescents, greater experience of dissociative symptoms was associated with lower heart rate during a stressful interview. Our results are consistent although not identical to the research of Griffin et al. (1997), which found that individuals reporting the most dissociative symptoms for the time of a prior traumatic event showed a suppression of autonomic physiological responses when subsequently discussing the event. Our results are also consistent with the Delahanty et al. (2003) finding of peritraumatic dissociation being associated with low urinary norepinephrine and epinephrine in supporting the association of lower physiological arousal with dissociation. Our results are also consistent with the Williams et al. (2003) case study in which a woman experienced considerable depersonalization while her heart rate slowed during reminders of a traumatic event. This growing body of evidence underscores that objective measures such as heart rate can reveal physiological characteristics associated with the subjective experience of dissociative symptoms. Furthermore, the evidence that high levels of dissociative symptoms may be related to a suppression of autonomic physiological responses to stress support Bremner’s conceptualization (Bremner, 1999) that dissociative symptoms comprise one of two subtypes of the acute stress response, differing physiologically as well as subjectively from a predominantly hyperarousal or intrusive symptom response. Dissociative symptoms in this study were assessed using the SCID-D, assessing dissociative symptoms occurring in the previous week that are not keyed to a specific event. In contrast, the Griffin et al. (1997) and Delahanty et al. (2003) studies used a measure of the peritraumatic dissociation that occurred at the time of the traumatic event. Thus, the finding that greater dissociation is related to a lower heart rate during a stressful interview has been found using two different measures of dissociation, suggesting the robustness of this relationship. Furthermore, we found that lower mean heart rate during the interview was significantly associated with two specific types of dissociation—derealization and identity alteration. Perhaps differences in physiological responses such as heart rate are associated with experiencing partic-

Koopman, Carrion, Butler, Sudhakar, Palmer, and Steiner ular dissociative symptoms rather than dissociative symptoms in general. Further research will need to reexamine for such relationships. The mean heart rates of delinquent adolescents were elevated compared to nonclinical samples of high school students, who on average experience heart rates on these tasks in the range of mid-to-upper 70s in beats per minute (Steiner et al., 2002). The high dissociators among the delinquent adolescents were more comparable to the high school sample in showing lower heart rates. Perhaps the high overall mean heart rate of the delinquent adolescents is attributable to their having experienced greater abuse and/or neglect, which was itself associated with higher mean heart rate. The tremendous abuse and neglect experienced by these delinquent adolescents compared to nonclinical samples (Carrion & Steiner, 2000) may be a key factor in leading to higher mean heart rates in response to the speech task than has been found in high school adolescents. Even within this highly traumatized sample, the experience of greater abuse and neglect is significantly associated with higher mean heart rate. This finding is consistent with previous studies (e.g., Lepore et al., 1997), which have demonstrated that exposure to stressful life events is linked to higher sympathetic arousal when individuals are faced with reminders of these events or to new challenges, although this interpretation is limited by lack of data on whether youths’ higher mean heart rates were associated with speaking about previous abuse or neglect experiences. The findings that greater physical neglect and emotional abuse were particularly associated with higher heart rate suggest that these may be particularly stressful experiences that lead to hyperresponsiveness to the interviews, but further research will need to try to replicate and understand these findings. The finding that girls compared to boys had higher mean heart rates during the interview is consistent with the findings of several previous studies (Allen & Matthews, 1997; Tardy & Allen, 1998). However, in this study, the lack of a baseline comparison for heart rate leaves open the possible interpretation that the girls’ heart rates are higher because they started out higher at baseline, as previously suggested by findings with a nonclinical sample of adolescents (Steiner et al., 2002), rather than that girls’ heart rates increased more during the course of the interview than did those of the boys. It is difficult to interpret the unexpected finding that youths who were instructed to speak freely about their thoughts, compared to those instructed to describe their most stressful life event, had higher mean heart rates. Potentially, youths could discuss abuse or neglect in either condition. One interpretation is that, given the high level

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Dissociation, Abuse and Neglect, and Heart Rate of adverse childhood experiences reported by this sample, the unstructured nature of the free association task allowed this disturbing material to creep into consciousness, thereby elevating heart rate. It may be intrinsically more stressful to respond to projective tasks without the familiar structure of describing a specific kind of event. This is consistent with the psychodynamic formulation that free association allows material into consciousness that would otherwise be defended against (Freud, 1953). We did not formally analyze the content of youths’ speeches, but we observed that during the free association task, youths often discussed highly stressful events such as gang violence. Future research should more systematically examine the content of youths’ remarks when they are asked to free associate to evaluate the extent to which stressful content is discussed and also to examine what youths discuss in the stressful event interview condition. This study did not control for a number of factors that should be considered in research on heart rate, such as fitness level, prior caffeine intake, smoking, and food recently ingested. Because heart rate is the only physiological measure that we examined in this study, future research should examine additional measures such as blood pressure reactivity and skin conductance responses. Also, we do not know whether participants in this study who score high on the SCID-D actually made use of dissociative defenses when they were engaged in a stressful interview, and we do not know whether PTSD symptoms affected their responses during the interview. Future research is needed to examine more closely the relationship between dissociative symptoms, length of time since experiencing abuse and neglect, PTSD, and heart rate during potentially stressful interviews. Research should include an initial period assessing heart rate during a neutral interview to establish a baseline heart rate and to allow for examination of changes in mean heart rate. This study’s conclusions may be limited by the examination of the relationship between dissociative symptoms and heart rate during two specific types of interview tasks, free association describing a stressful event. Also, our sample size was not large enough to examine interactions of variables, such as by gender, dissociation level, and instructional task. Previous evidence of gender differences in cardiovascular reactivity according to differences in experimental conditions (Wilson et al., 1999), suggests that the pattern of gender differences in cardiovascular reactivity may be specific to the nature of the task under consideration, and thus merits further examination. Despite such limitations, the results of this study indicate support for generalizing to delinquent adolescents of both sexes, the Griffin et al. (1997) finding with women rape survivors that dissociative symptoms are associated

53 with lower heart rate during a stressful interview. Further investigation is needed to identify the underlying mechanisms and to determine whether this relationship develops over the course of early childhood or whether dissociative experiences are congenitally linked to lower heart rate. Acknowledgments This study was funded by NIMH grant 5T32 MH19908-03 to Dr Steiner and an Eli Lilly Pilot Research Award to Dr Carrion. The investigators thank the San Mateo County Juvenile Probation Department in California for their participation. We also thank Dr Paula Schnurr for her statistical editorial feedback. References Allen, M. T., & Matthews, K. A. (1997). Hemodynamic responses to laboratory stressors in children and adolescents: The influences of age, race, and gender. Psychophysiology, 34, 329–339. Blanchard, E. B., Hickling, E. J., Buckley, T. C., Taylor, A. E., Vollmer, A., & Loos, W. R. (1996). Psychophysiology of posttraumatic stress disorder related to motor vehicle accidents: Replication and extension. Journal of Consulting and Clinical Psychology, 64, 742–751. Bremner, J. D. (1999). Acute and chronic responses to psychological trauma: Where do we go from here? American Journal of Psychiatry, 156, 349–351. Bremner, J. D., Southwick, S., Brett, E., Fontana, A., Rosenheck, R., & Charney, D. S. (1992). Dissociation and posttraumatic stress disorder in Vietnam combat veterans. American Journal of Psychiatry, 149, 328–332. Bryant, R., & Harvey, A. G. (2000). New DSM-IV diagnosis of acute stress disorder [Letter to the editor]. American Journal of Psychiatry, 157, 1889–1891. Bryant, R., Harvey, A. G., Guthrie, R. M., & Moulds, M. L. (2000). A prospective study of psychophysiological arousal, acute stress disorder, and posttraumatic stress disorder. Journal of Abnormal Psychology, 109, 341–344. Butler, L. D. (2000). Validity and utility of the acute stress disorder (ASD) symptom criteria and diagnosis [Letter to the editor]. American Journal of Psychiatry, 157, 189. Butler, L. D., Dur´an, R. E. F., Jasiukaitus, P., Koopman, C., & Spiegel, D. (1996). Hypnotizability and traumatic experience: A diathesisstress model of dissociative symptomatology. American Journal of Psychiatry, 153(Suppl.), 42–63. Carrion, V. G., & Steiner, H. (2000). Trauma and dissociation in delinquent adolescents. Journal of the American Academy of Child and Adolescent Psychiatry, 39, 353–359. Casada, J. H., Amdur, R., Larsen, R., & Liberzon, I. (1998). Psychophysiologic responsivity in posttraumatic stress disorder: Generalized hyperresponsiveness versus trauma specificity. Biological Psychiatry, 44, 1037–1044. Delahanty, D. L., Royer, D. K., Raimonde, A. J., & Spoonster, E. (2003). Peritraumatic dissociation is inversely related to catecholamine levels in initial urine samples of motor vehicle accident victims. Journal of Trauma and Dissociation, 4(1), 65–80. Fink, L., Bernstein, D., Handelsman, L., Fotte, J., & Lovejoy, M. (1995). Initial reliability and validity of the Childhood Trauma Interview: A new multidimensional measure of childhood interpersonal trauma. American Journal of Psychiatry, 152, 1329–1335. Freud, S. (1953). The interpretation of dreams. In J. Strachey (Ed.), Standard edition of the complete psychological works of Sigmund Freud (Vols. 4 and 5). London: Hogarth Press.

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