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Letters to the Editor

Confidence in the "Iron Dome" Missile Defense System Combined With a Sense of Resilience Reduced the Effect of Exposure on Posttraumatic Stress Disorder Symptoms After Missile Attacks

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Confidence in the "Iron Dome" Missile Defense System Combined With a Sense of Resilience Reduced the Effect of Exposure on Posttraumatic Stress Disorder Symptoms After Missile Attacks

To the Editor: In this study, we examined posttraumatic stress disorder (PTSD) symptoms in Israeli civilians following the 2014 Israel-Gaza conflict, during which more than 4,500 missiles were fired on 70% of the Israeli population.1 We addressed how 2 main putative protective factors may mitigate the impact of exposure to missile threat on PTSD symptom development.2 The first factor, resilience, refers to a trait or an intrapsychological process that results in positive adaptation to trauma.3-5 Psychological resilience, potentially related to adaptive belief systems,6 typically reduces the detrimental effects of trauma exposure on PTSD symptoms.7,8 Herein we address whether resilience effects can be strengthened when coupled with a second factor, namely, one’s belief in the external protection of the new "Iron Dome" missile defense system. This system was developed in a joint United States/Israel venture, which was employed for the first time on a national scale during the 2014 Israel-Gaza conflict.1 Therefore, our main research question was whether internal resilience coupled with belief in external protection further mitigates the impact of exposure on PTSD.

Methods. This study was conducted from December 2014 until January 2015. Respondents (N = 1,268, mean ± SD age = 36.97 ± 13.62, 53.2% women) completed an online questionnaire comprising exposure level to the missile threat, PTSD symptoms (PTSD Checklist for DSM-5,9 Cronbach α = .93), and resilience (Connor-Davidson Resilience Scale,10 Cronbach α = .91)—3 items addressing confidence in the Iron Dome system (Cronbach α = .83). We additionally examined a single item addressing estimated probability of Iron Dome success rate (0%-100%). Demographics (age, sex, marital status) and subjective health were also recorded. For more details, see eAppendix 1 at PSYCHIATRIST.COM.

Results. Resilience was moderately related to confidence in the Iron Dome system (r = 0.21, P < .001) and unrelated to probability of successful intercepts attributed to the system (r = -0.001). These correlations suggest that resilience and beliefs regarding the Iron Dome are relatively distinctive variables (for additional descriptive statistics, see Supplementary eTable 1). Next, PTSD symptoms were regressed in a hierarchical regression analysis on exposure level, resilience, confidence in the Iron Dome system, their three 2-way interactions, and their single 3-way interaction. The significant 3-way interaction (B = −0.81, t1,247 = −2.32, P = .02) was probed by a computational procedure11 applying equations estimating effects when confidence in the Iron Dome system and national resilience values were at ± 1 SD from the mean. Level of exposure was positively related to PTSD symptoms under all conditions (P < .01) except under high resilience coupled with high-level confidence in the Iron Dome system, in which the effect of exposure on PTSD was no longer significant (B = 0.83, t1,247 = 1.88, P = .07). Similarly, the 3-way interaction between exposure, resilience, and estimated probability of Iron Dome success rate was significant (B = −0.06, t1,227 = −2.65, P = .008). Again, level of exposure was positively related to PTSD symptoms under all conditions (P < .01) except for high resilience combined with high estimated probability of successful Iron Dome intercepts, where the effect of exposure on PTSD was no longer significant (B = 0.72, t1,227 = 1.61, P = .10). Both 3-way interactions remained significant after controlling for age, sex, marital status, and subjective health (P < .05). Approximately 13% of the variance in PTSD symptoms was explained by each model (Table 1).

Table 1

Click figure to enlarge

Following these findings, high resilience and high confidence in Iron Dome protection may be seen as 2 aspects of an adaptive belief system, respectively referring to the estimated internal and external sources of strength. The combination of these 2 components may have an overadditive effect on one’s sense of safety, an important factor associated with reduced symptoms in the aftermath of traumatic events.12 Although sampling was constrained and possibly biased by Internet usage, these results call for additional examination of the mutual effects of estimated inner strength, coupled with belief in or appraisal of external protection, on PTSD symptoms.

References

1. 2014 Israel-Gaza Conflict. Wikipedia Web site. http://en.wikipedia.org/wiki/2014_Israel%E2%80%93Gaza_conflict. Updated December 15, 2015. Accessed December 15, 2015.

2. Ben-Ezra M, Palgi Y, Essar N. The impact of exposure to war stress on hospital staff: a preliminary report. J Psychiatr Res. 2008;42(5):422-423. PubMed doi:10.1016/j.jpsychires.2007.02.004

3. Luthar SS, Cicchetti D, Becker B. The construct of resilience: a critical evaluation and guidelines for future work. Child Dev. 2000;71(3):543-562. PubMed doi:10.1111/1467-8624.00164

4. Connor KM. Assessment of resilience in the aftermath of trauma. J Clin Psychiatry. 2006;67(suppl 2):46-49. PubMed

5. Layne CM, Warren JS, Watson PJ, et al. Risk, vulnerability, resistance, and resilience: towards an integrative conceptualization of posttraumatic adaptation. In: Friedman MJ, Keane TM, Resick PA, eds. Handbook of PTSD: Science and Practice. New York, NY: Guilford Press; 2007:497-520.

6. Kaplan Z, Matar MA, Kamin R, et al. Stress-related responses after 3 years of exposure to terror in Israel: are ideological-religious factors associated with resilience? J Clin Psychiatry. 2005;66(9):1146-1154. PubMed doi:10.4088/JCP.v66n0910

7. Green KT, Calhoun PS, Dennis MF, et al. Mid-Atlantic Mental Illness Research, Education and Clinical Center Workgroup. Exploration of the resilience construct in posttraumatic stress disorder severity and functional correlates in military combat veterans who have served since September 11, 2001. J Clin Psychiatry. 2010;71(7):823-830. PubMed doi:10.4088/JCP.09m05780blu

8. Besser A, Zeigler-Hill V, Weinberg M, et al. Intrapersonal resilience moderates the association between exposure-severity and PTSD symptoms among civilians exposed to the 2014 Israel-Gaza Conflict. Self Ident. 2015;14(1):1-15. doi:10.1080/15298868.2014.966143

9. Weathers FW, Litz BT, Keane TM, et al. The PTSD Checklist for DSM-5 (PCL-5): scale available from the National Center for PTSD, 2013. US Department of Veterans Affairs Web site. www.ptsd.va.gov. Updated December 3, 2015. Accessed December 15, 2015.

10. Campbell-Sills L, Stein MB. Psychometric analysis and refinement of the Connor-Davidson Resilience Scale (CD-RISC): validation of a 10-item measure of resilience. J Trauma Stress. 2007;20(6):1019-1028. PubMed doi:10.1002/jts.20271

11. Hayes AF. Introduction to Mediation, Moderation, and Conditional Process Analysis: A Regression-Based Approach. New York, NY: Guilford Press; 2013.

12. Bleich A, Gelkopf M, Melamed Y, et al. Mental health and resiliency following 44 months of terrorism: a survey of an Israeli national representative sample. BMC Med. 2006;4(1):21-31. PubMed doi:10.1186/1741-7015-4-21

Yaakov Hoffman, PhDa

hoffmay@gmail.com

Sara Cohen-Fridel, MAb

Ehud Bodner, PhDa,c

Ephraim Grossman, PhDa

Amit Shrira, PhDa

aInterdisciplinary Department of Social Sciences, bSchool of Education, and cDepartment of Music, Bar-Ilan University, Ramat Gan, Israel

Potential conflicts of interest: None reported.

Funding/support: None reported.

Supplementary material: Available at PSYCHIATRIST.COM.

J Clin Psychiatry 2016;77(3):407-408

dx.doi.org/10.4088/JCP.15l10024

© Copyright 2016 Physicians Postgraduate Press, Inc.

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