Henna Haravuori1, Laura Suomalainen1, Mauri Marttunen1,2
A controlled follow-up study of adolescents exposed to a school shooting – evaluation of dissociative symptoms
1 Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, and Department of Adolescent Psychiatry, Helsinki University Central Hospital, Helsinki, Finland
2 Helsinki University, Helsinki, Finland
Address: National Institute for Health and Welfare (MIPO/LAMI), P.O. Box 30, 00271 Helsinki, Finland.
Phone: +358-20-610 6000
Fax: +358- 20-610 7191
Conflict of interest
The authors declare that they have no conflict of interest.
Keywords
school violence, trauma, dissociation, posttraumatic stress disorder, PTSD
Objective
On November 7th 2007, a student shot eight people and himself in Jokela High School in Finland. Several students were exposed to the shooting and perceived potential threat to life. This study aims to evaluate dissociative experiences among the exposed and comparison students. Associations between dissociative experiences measured by questions from the adolescent dissociative experiences scale, other psychological outcomes and background factors were analyzed.
Background
Traumatic events may have long-term psychological effects by causing diverse anxiety and affective disorders and posttraumatic stress disorder (PTSD). Dissociative symptoms may also result from traumatisation and dissociative symptoms entangle with PTSD. However, dissociation is a broader phenomenon that is characterized by disruptions in memory, consciousness, identity and perception of the environment (Diseth 2005). Dissociation may also manifest as disturbances of sensory and motor functions. Traumatic experience is incomprehensible to mind and may result in fragmentary memories, some of them photographic, some even faulty. These fragmentary memories are seen as basis of the traumatic dissociation (Van der Kolk and Fisler, 1995). Dissociation has been observed in childhood and adolescent trauma (physical and sexual abuse, and neglect). Self-harming behaviour has also been associated with dissociative symptoms among adolescents (Tolmunen et al. 2008).
We hypothesized that we could observe dissociative symptoms among those exposed to a school shooting and dissociative symptoms would associate with other psychological symptoms.
Methods
The data presented here were collected using a questionnaire administered in March 2008 and 2009. All the students of the Jokela High school, aged 13–19 years, were invited to participate in the study (N=474). The comparison group was drawn from the students of Pirkkala High School, aged 13–19 (N=878). Participation was voluntary and participants were asked to sign a written informed consent. Signed informed consent was required from parent or guardian of the students under 15 years. Students filled in questionnaires in classrooms. The questionnaires were mailed with a return envelope to the absent students. The study protocol was accepted by the Ethics Committee of Helsinki University Central Hospital.
231 (49%) students participated in baseline questionnaire in Jokela, 2008, and 168 (73%) participated also in follow-up. Non-participation was related to male sex. Drop-out was associated with male sex and using alcohol more often than once a month. 526 (60%) students participated in Pirkkala at baseline, and 406 (77%) continued in follow-up. Non-participation was more common among males than females. Drop-out was associated with older age, living arrangement other than both biological parents, less social support from family and using alcohol more often than once a month.
The questionnaire asked about background factors, exposure to the shooting and about the psychosocial support or care received. The Impact of Event Scale (IES) was used to assess posttraumatic distress(Horowitz et al., 1979). The 15 questions were used to calculate the sum scores, resulting in a range of 0-75. Internal reliability is satisfactory (Cronbach’s α 0.86). The cut-off point for having posttraumatic distress was set at 19/20 and for high levels of posttraumatic stress at 34/35, which predicts clinical PTSD.
The General Health Questionnaire (GHQ) 12-item version was used to measure general psychological symptoms. The range of sum scores is 0-12. The optimal cut-off point for detecting psychiatric disturbance(Aalto-Setälä et al., 2002) is 3/4 (the Finnish version of GHQ-12, Crohnbach’s α 0.94). In addition, two questions of suicidal thoughts were included. Six categories for the severity of the trauma exposure were created based on the experienced threat to life and losses suffered: no exposure (control school student), mild exposure, moderate exposure, significant exposure (e.g. had to act to escape the shooter or had to hide to avoid life danger), severe exposure (e.g. saw somebody threatened by gun) and extreme exposure.
Dissociative experiences were assessed with nine questions from the adolescent dissociative experiences scale (A-DES) at follow-up (Armstrong et al. 1997). The questions were: I find myself someplace and I don't remember how I got there. I find writings, drawings or letters that I must have done but I can't remember doing. I find myself standing outside of my body, watching myself as if I were another person. My family members and friends tell that sometimes I do not recognize them. I feel like I am in a fog or spaced out and things around me seem unreal. My body feels as if it doesn't belong to me. I feel like there are different people inside of me. I hear voices in my head that are not mine. People tell me that I sometimes act so differently that I seem like a different person. The questions were answered on 11-point Likert scale (0-10, never-always). The mean score of the items was used for the analyses. Crohnbach’s α was 0.99 for the Jokela students and 0.97 for Pirkkala students.
Differences between the groups were tested using the chi-square test, analysis of variance (ANOVA), and Scheffé post hoc analysis when appropriate. Latent class analysis was used to construct symptom trajectories of from IES and GHQ symptom scales. P-values <0.05 were considered statistically significant.
Results
Most of the Jokela High School students had been exposed at least significantly to the traumatic event; 7.7% were extremely exposed, 17.3% severely, 69.0% significantly and 6.0% mildly or moderately exposed. Symptom levels measured by IES and GHQ-12 at baseline and follow-up are shown in Table 1. We have previously found that female gender and the level of exposure are strong predictors for symptoms. Latent class analysis was used to estimate symptom trajectory classes with the students that had completed symptom scales at both time points (Table 3).
Mean scores for dissociative symptoms did not differ between the exposed students 0.53 (SD=1.04) and the comparison students 0.55 (SD=1.01), p=0.782. Dissociative symptoms did not associate with gender, socioeconomic status (SES), living arrangements or frequency of alcohol consumption at either basely or follow-up or life adversities among the exposed students. Dissociative symptoms associated with previous traumatic experiences, p=0.030 but not with new traumatic events. Level of exposure did not have an effect on dissociative symptoms; mild-to-moderate exposure M=0.41 (SD=0.70), significant exposure M=0.55 (SD=1.05), severe-to-extreme exposure M=0.48 (SD=1.08), p=0.886. Dissociative symptoms did not associate with gender, SES or living arrangements among the comparison students. Association was found with frequency of alcohol consumption at baseline, p=0.005, but not at follow-up, although close to significant level, p=0.074. Life adversities had no effect on dissociative symptoms but both earlier and later traumatic experiences associated with dissociative symptoms, both p=0.005.
Dissociative symptoms associated strongly with other symptom scale scores (Among the exposed students: IES scores at baseline p=0.001, at follow-up p<0.001, GHQ-12 at baseline p=0.004, at follow-up p<0.001. Among the comparison students: IES scores at baseline p<0.001, at follow-up p<0.001, GHQ-12 at baseline p<0.001, at follow-up p<0.001.) (Table 2). Dissociative symptoms associated also strongly with suicidal thoughts (Exposed students: at baseline p<0.001, at follow-up p<0.001. Comparison students: At baseline p<0.001, at follow-up p<0.001.) (Table 2).
Dissociative symptoms differed between the posttraumatic symptom trajectories among the exposed students p=0.005, but post hoc analyses showed significant difference only between resilient and chronic trajectories, p=0.007. Likewise, dissociative symptoms differed between psychological symptom trajectories, p<0.001. Post hoc analyses showed significant differences between low/high, low/increase, and high/decrease trajectories. Among comparison students significant differences were observed between resilient/chronic, resilient/late-onset, chronic/recovery, and late-onset/chronic posttraumatic symptom trajectories. Dissociative symptoms differed significantly also between high psychological symptom trajectory versus all other trajectories.
Conclusions
Dissociative symptoms associated with posttraumatic symptoms, psychological symptoms and suicidal thoughts among the studied student groups. This suggests that dissociative symptoms are associated with overall vulnerability to psychopathology. Dissociative symptom levels did not differ among those exposed to a school shooting and those distant to a school shooting. Further, level of exposure had no effect on dissociative symptoms among the exposed students. Possibly complex or repetitive traumatisation cause dissociative symptoms and mental states more typically than single traumatic event among adolescents.
References
Armstrong JG, Putnam FW, Carlson EB, et al. Development and validation of a measure of adolescent dissociation. The adolescent dissociative experiences scale. J Nerv Ment Dis 1997;185:481-97.
Diseth TH. Dissociation in children and adolescents as reaction to trauma - an overview of conceptual issues and neurobiological factors. Nord J Psychiatry 2005;59:79-91.
Tolmunen T, Rissanen ML, Hintikka J, et al. Dissociation, self-cutting, and other self-harm behavior in general population of Finnish adolescents. J Nerv Ment Dis 2008;196:768-71.
Van der Kolk, Fisler R. Dissociation and fragmented nature of traumatic memories. Overview and exploratory study. J Trauma Stress 1995;8:505-525.
Table 1. Posttraumatic distress and psychiatric disturbance among the exposed and comparison students.
Baseline / One year follow-upExposed / Comparison / Exposed / Comparison
(n=167/168) / (n=390/404) / (n=166/168) / (n=357/406)
% / (n) / % / (n) / % / (n) / % / (n)
Posttraumatic distress
IES 0-19 / 53.9 / (90) / 83.8 / (327) / 69.3 / (115) / 80.4 / (287)
IES 20-34 / 24.6 / (41) / 10.5 / (41) / 14.5 / (24) / 10.6 / (38)
IES 35-75 / 21.6 / (36) / 5.6 / (22) / 16.3 / (27) / 9.0 / (32)
χ2 = 58.112, df = 2, p<0.001 / χ2 = 8.566, df = 2, p=0.014
Psychiatric disturbance
GHQ ≤ 3 / 69.0 / (116) / 89.6 / (362) / 76.2 / (128) / 85.7 / (348)
GHQ ≥ 4 / 31.0 / (52) / 10.4 / (42) / 23.8 / (40) / 14.3 / (58)
χ2 = 36.511, df = 1, p<0.001 / χ2 = 7.613, df = 1, p=0.006
Table 2. Dissiciative symptoms by posttraumatic distress, psychiatric disturbance and suicidal thoughts
among exposed and comparison students.
Baseline / One year follow-upExposed / Comparison / Exposed / Comparison
M / (SD) / M / (SD) / M / (SD) / M / (SD)
Posttraumatic distress
IES 0-19 / 0.27 / (0.57) / 0.44 / (0.90) / 0.30 / (0.75) / 0.40 / (0.79)
IES 20-34 / 0.70 / (1.29) / 0.76 / (0.78) / 0.71 / (1.06) / 0.98 / (1.26)
IES 35-75 / 0.96 / (1.43) / 1.96 / (1.94) / 1.26 / (1.60) / 1.61 / (1.53)
Psychiatric disturbance
GHQ ≤ 3 / 0.37 / (0.81) / 0.45 / (0.88) / 0.26 / (0.64) / 0.40 / (0.83)
GHQ ≥ 4 / 0.87 / (1.37) / 1.38 / (1.59) / 1.34 / (1.53) / 1.39 / (1.51)
Suicidal thoughts
No / 0.43 / (0.86) / 0.49 / (0.93) / 0.39 / (0.82) / 0.48 / (0.89)
Yes / 1.45 / (1.91) / 1.97 / (1.63) / 1.90 / (1.78) / 1.84 / (1.92)
Table 3. Dissociative symptoms by posttraumatic distress (IES) and general psychological symptom
(GHQ) trajectory groups among the exposed and comparison students.
Exposed / Comparisonn / M / (SD) / n / M / (SD)
Posttraumatic distress
Resilient / 68 / 0.28 / (0.66) / 224 / 0.30 / (0.72)
Recovery / 33 / 0.40 / (1.00) / 29 / 0.65 / (0.69)
Late-onset / 26 / 0.62 / (1.13) / 71 / 1.08 / (1.32)
Chronic / 36 / 1.02 / (1.41) / 18 / 1.93 / (1.53)
Psychological symptoms
Low / 92 / 0.23 / (0.66) / 319 / 0.40 / (0.85)
Decrease / 44 / 0.40 / (0.57) / 41 / 0.72 / (0.94)
Increase / 14 / 1.13 / (1.17) / 24 / 0.93 / (0.95)
High / 16 / 2.00 / (1.95) / 16 / 2.43 / (1.96)
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