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Dimensional structure and course of post-traumatic stress symptomatology in World Trade Center responders

  • R. H. Pietrzak (a1) (a2), A. Feder (a3), C. B. Schechter (a4), R. Singh (a3), L. Cancelmo (a3), E. J. Bromet (a5), C. L. Katz (a3), D. B. Reissman (a6), F. Ozbay (a3), V. Sharma (a3), M. Crane (a7), D. Harrison (a8), R. Herbert (a7), S. M. Levin (a7), B. J. Luft (a9), J. M. Moline (a10), J. M. Stellman (a11), I. G. Udasin (a12), R. El-Gabalawy (a13), P. J. Landrigan (a7) and S. M. Southwick (a1) (a2)...

Post-traumatic stress disorder (PTSD) in response to the World Trade Center (WTC) disaster of 11 September 2001 (9/11) is one of the most prevalent and persistent health conditions among both professional (e.g. police) and non-traditional (e.g. construction worker) WTC responders, even several years after 9/11. However, little is known about the dimensionality and natural course of WTC-related PTSD symptomatology in these populations.


Data were analysed from 10 835 WTC responders, including 4035 police and 6800 non-traditional responders who were evaluated as part of the WTC Health Program, a clinic network in the New York area established by the National Institute for Occupational Safety and Health. Confirmatory factor analyses (CFAs) were used to evaluate structural models of PTSD symptom dimensionality; and autoregressive cross-lagged (ARCL) panel regressions were used to examine the prospective interrelationships among PTSD symptom clusters at 3, 6 and 8 years after 9/11.


CFAs suggested that five stable symptom clusters best represent PTSD symptom dimensionality in both police and non-traditional WTC responders. This five-factor model was also invariant over time with respect to factor loadings and structural parameters, thereby demonstrating its longitudinal stability. ARCL panel regression analyses revealed that hyperarousal symptoms had a prominent role in predicting other symptom clusters of PTSD, with anxious arousal symptoms primarily driving re-experiencing symptoms, and dysphoric arousal symptoms primarily driving emotional numbing symptoms over time.


Results of this study suggest that disaster-related PTSD symptomatology in WTC responders is best represented by five symptom dimensions. Anxious arousal symptoms, which are characterized by hypervigilance and exaggerated startle, may primarily drive re-experiencing symptoms, while dysphoric arousal symptoms, which are characterized by sleep disturbance, irritability/anger and concentration difficulties, may primarily drive emotional numbing symptoms over time. These results underscore the importance of assessment, monitoring and early intervention of hyperarousal symptoms in WTC and other disaster responders.

Corresponding author
* Address for correspondence: R. H. Pietrzak, Ph.D., M.P.H., National Center for Posttraumatic Stress Disorder, VA Connecticut Healthcare System, Yale University School of Medicine, 950 Campbell Avenue 151E, West Haven, CT, 06516, USA. (Email:
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APA (2000). Diagnostic and Statistical Manual of Mental Disorders, 4th edn., text revision. American Psychiatric Press: Washington, DC.
APA (2013). Diagnostic and Statistical Manual of Mental Disorders, 5th edn. American Psychiatric Publishing: Arlington, VA.
Armour C, Carragher N, Elhai JD (2013 a). Assessing the fit of the dysphoric arousal model across two nationally representative epidemiological surveys: The Australian NSMHWB and the United States NESARC. Journal of Anxiety Disorders 27, 109115.
Armour C, Elhai JD, Richardson D, Ractliffe K, Wang L, Elklit A (2012). Assessing a five factor model of PTSD: is dysphoric arousal a unique PTSD construct showing differential relationships with anxiety and depression? Journal of Anxiety Disorders 26, 368376.
Armour C, Raudzah Ghazali S, Elklit A (2013 b). PTSD's latent structure in Malaysian tsunami victims: assessing the newly proposed dysphoric arousal model. Psychiatry Research 206, 2632.
Berninger A, Webber MP, Cohen HW, Gustave J, Lee R, Niles JK, Chiu S, Zeig-Owens R, Soo J, Kelly K, Prezant DJ (2010). Trends of elevated PTSD risk in firefighters exposed to the World Trade Center disaster: 2001–2005. Public Health Reports 125, 556566.
Bowler RM, Han H, Gocheva V, Nakagawa S, Alper H, DiGrande L, Cone JE (2010). Gender differences in probable posttraumatic stress disorder among police responders to the 2001 World Trade Center terrorist attack. American Journal of Industrial Medicine 53, 11861196.
Bremner JD, Southwick SM, Darnell A, Charney DS (1996). Chronic PTSD in Vietnam combat veterans: course of illness and substance abuse. American Journal Psychiatry 153, 369375.
Bryant RA, Harvey AG, Guthrie RM, Moulds ML (2003). Acute psychophysiological arousal and posttraumatic stress disorder: a two-year prospective study. Journal of Traumatic Stress 16, 439443.
Centers for Disease Control and Prevention (2004). Mental health status of World Trade Center rescue and recovery workers and volunteers – New York City, July 2002–August 2004. Morbidity and Mortality Weekly Report 53, 812815.
Creamer M, Burgess P, Pattison P (1992). Reaction to trauma: a cognitive processing model. Journal of Abnormal Psychology 101, 452459.
Cukor J, Wyka K, Jayasinghe N, Weathers F, Giosan C, Leck P, Roberts J, Spielman L, Crane M, Difede J (2011). Prevalence and predictors of posttraumatic stress symptoms in utility workers deployed to the World Trade Center following the attacks of September 11, 2001. Depression and Anxiety 28, 210217.
Elhai JD, Biehn TL, Armour C, Klopper JJ, Frueh BC, Palmieri PA (2011). Evidence for a unique PTSD construct represented by PTSD's D1–D3 symptoms. Journal of Anxiety Disorders 25, 340345.
Elhai JD, Layne CM, Steinberg AM, Brymer MJ, Briggs EC, Ostrowski SA, Pynoos RS (2013). Psychometric properties of the UCLA PTSD reaction index. part II: investigating factor structure findings in a national clinic-referred youth sample. Journal of Traumatic Stress 26, 1018.
Elhai JD, Palmieri PA (2011). The factor structure of posttraumatic stress disorder: a literature update, critique of methodology, and agenda for future research. Journal of Anxiety Disorders 25, 849854.
Fan X, Sivo SA (2009). Using goodness-of-fit indexes in assessing mean structure invariance. Structural Equation Modeling 16, 5467.
Foa EB, Riggs DS, Gershuny BA (1995). Arousal, numbing, and intrusion: symptom structure of PTSD following assault. American Journal of Psychiatry 152, 116120.
Herbert R, Moline J, Skloot G, Metzger K, Baron S, Luft B, Markowitz S, Udasin I, Harrison D, Stein D, Todd A, Enright P, Stellman JM, Landrigan PJ, Levin SM (2006). The World Trade Center disaster and the health of workers: five-year assessment of a unique medical screening program. Environmental Health Perspectives 114, 18531858.
Hinton DE, Hofmann SG, Pollack MH, Otto MW (2009). Mechanisms of efficacy of CBT for Cambodian refugees with PTSD: improvement in emotion regulation and orthostatic blood pressure response. CNS Neuroscience and Therapeutics 15, 255263.
Hoge EA, Worthington JJ, Nagurney JT, Chang Y, Kay EB, Feterowski CM, Katzman AR, Goetz JM, Rosasco ML, Lasko NB, Zusman RM, Pollack MH, Orr SP, Pitman RK (2012). Effect of acute posttrauma propranolol on PTSD outcome and physiological responses during script-driven imagery. CNS Neuroscience and Therapeutics 18, 2127.
Horowitz MJ (2001). Stress Response Syndromes, 3rd edn. Jason Aronson: New York.
Hu L, Bentler PM (1998). Fit indices in covariance structural modeling: sensitivity to underparameterized model misspecification. Psychological Methods 3, 424453.
Hu L, Bentler PM (1999). Cutoff criteria for fit indexes in covariance structure analysis: conventional criteria versus new alternatives. Structural Equation Modeling 6, 155.
Jöreskog KG (1979). Statistical estimation of structural models in longitudinal developmental investigations. In Longitudinal Research in the Study of Behavior and Development (ed. Nesselroade J. R. and Baltes P. B.), pp. 303352. Academic Press: New York.
Keane TM, Fairbank JA, Caddell RT, Zimering RT, Bender ME (1985). A behavioral approach to assessing and treating PTSD in Vietnam veterans. In Trauma and its Wake (ed. Figley C. R.), pp. 257294. Brunner/Mazel: New York.
King DW, Leskin GA, King LA, Weathers FW (1998). Confirmatory factor analysis of the Clinician-Administered PTSD Scale: evidence for the dimensionality of posttraumatic stress disorder. Psychological Assessment 10, 9096.
Lawrence JW, Fauerbach J, Munster A (1996). Early avoidance of traumatic stimuli predicts chronicity of intrusive thoughts following burn injury. Behaviour Research and Therapy 34, 643646.
Leskin GA, Kaloupek DG, Keane TM (1998). Treatment for traumatic memories: review and recommendations. Clinical Psychology Review 18, 9831001.
Lucchini RG, Crane MA, Crowley L, Globina Y, Milek DJ, Boffetta P, Landrigan PJ (2012). The World Trade Center Health Surveillance Program: results of the first 10 years and implications for prevention. Giomale Italiano di Medicina del Lavoro ed Ergonomia 34 (Suppl. 3), 529533.
Luft BJ, Schechter C, Kotov R, Broihier J, Reissman D, Guerrera K, Udasin I, Moline J, Harrison D, Friedman-Jimenez G, Pietrzak RH, Southwick SM, Bromet EJ (2012). Exposure, probable PTSD and lower respiratory illness among World Trade Center rescue, recovery and clean-up workers. Psychological Medicine 42, 10691079.
Macdonald A, Monson CM, Doron-Lamarca S, Resick PA, Palfai TP (2011). Identifying patterns of symptom change during a randomized controlled trial of cognitive processing therapy for military-related posttraumatic stress disorder. Journal of Traumatic Stress 24, 268276.
Malta LS, Wyka KE, Giosan C, Jayasinghe N, Difede J (2009). Numbing symptoms as predictors of unremitting posttraumatic stress disorder. Journal of Anxiety Disorders 23, 223229.
Marshall GN, Schell TL, Glynn SM, Shetty V (2006). The role of hyperarousal in the manifestation of posttraumatic psychological distress following injury. Journal of Abnormal Psychology 115, 624628.
Marshall GN, Schell TL, Miles JNV (2013). A multi-sample confirmatory factor analysis of PTSD symptoms: what exactly is wrong with the DSM-IV structure? Clinical Psychology Review 33, 5466.
Mayer L, Carrol S (1987). Testing for lagged, cotemporal and total dependence in cross-lagged panel analysis. Sociological Methods and Research 16, 187217.
Muthén B, Muthén L (2002). MPlus: The Comprehensive Modeling Program for Applied Researchers. Muthén and Muthén: Los Angeles, CA.
Nixon RDV, Nehmy T, Seymour M (2007). The effect of cognitive load and hyperarousal on negative intrusive memories. Behaviour Research and Therapy 45, 26522663.
Perrin MA, DiGrande L, Wheeler K, Thorpe L, Farfel M, Brackbill R (2007). Differences in PTSD prevalence and associated risk factors among World Trade Center disaster rescue and recovery workers. American Journal of Psychiatry 164, 13851394.
Palmieri PA, Weathers FW, Difede J, King DW (2007). Confirmatory factor analysis of the PTSD Checklist and the Clinician-Administered PTSD Scale in disaster workers exposed to the World Trade Center Ground Zero. Journal of Abnormal Psychology 116, 329341.
Pietrzak RH, Feder A, Singh R, Schechter CB, Bromet EJ, Katz CL, Reissman DB, Ozbay F, Sharma V, Crane M, Harrison D, Herbert R, Levin SM, Luft BJ, Moline JM, Stellman JM, Udasin IG, Landrigan PJ, Southwick SM (2013 a). Trajectories of PTSD risk and resilience in World Trade Center responders: an 8-year prospective cohort study. Psychological Medicine. Published online: 3 04 2013 . doi:10.1017/S0033291713000597.
Pietrzak RH, Galea S, Southwick SM, Gelernter J (2013 b). Examining the relation between the serotonin transporter 5-HTTPLR genotype x trauma exposure interaction on a contemporary phenotypic model of posttraumatic stress symptomatology: a pilot study. Journal of Affective Disorders 148, 123128.
Pietrzak RH, Gallezot JD, Ding YS, Henry S, Potenza MN, Southwick SM, Krystal JH, Carson RE, Neumeister A (2013 c). Association of posttraumatic stress disorder with reduced in vivo norepinephrine transporter density in locus coeruleus. JAMA Psychiatry 70, 11991205.
Pietrzak RH, Henry S, Southwick SM, Krystal JH, Neumeister A (2013 d). Linking in vivo brain serotonin type 1B receptor density to phenotypic heterogeneity of posttraumatic stress symptomatology. Molecular Psychiatry 18, 399401.
Pietrzak RH, Schechter CB, Bromet EJ, Katz CL, Reissman DB, Ozbay F, Sharma V, Crane M, Harrison D, Herbert R, Levin SM, Luft BJ, Moline JM, Stellman JM, Udasin IG, Landrigan PJ, Southwick SM (2012 a). The burden of full and subsyndromal posttraumatic stress disorder among police involved in the World Trade Center rescue and recovery effort. Journal of Psychiatric Research 46, 835842.
Pietrzak RH, Tsai J, Harpaz-Rotem I, Whealin JM, Southwick SM (2012 b). Support for a novel five-factor model of posttraumatic stress symptoms in three independent samples of Iraq/Afghanistan veterans: a confirmatory factor analytic study. Journal of Psychiatric Research 46, 317322.
Pietrzak RH, Van Ness PH, Fried TR, Galea S, Norris F (2012 c). Diagnostic utility and factor structure of the PTSD Checklist in older adults. International Psychogeriatrics 24, 16841696.
Pitman RK, Delahanty DL (2005). Conceptually driven pharmacologic approaches to acute trauma. CNS Spectrums 10, 99106.
Rabe S, Dörfel D, Zöllner T, Maercker A, Karl A (2006). Cardiovascular correlates of motor vehicle accident related posttraumatic stress disorder and its successful treatment. Applied Psychophysiology and Biofeedback 31, 315330.
Raftery AE (1995). Bayesian model selection in social research. Sociological Methodology 25, 111163.
Reddy MK, Anderson BJ, Liebschutz J, Stein MD (2013). Factor structure of PTSD symptoms in opioid-dependent patients rating their overall trauma history. Drug and Alcohol Dependence 132, 597602.
Ruggero CJ, Kotov R, Callahan JL, Kilmer JN, Luft BJ, Bromet EJ (2013). PTSD symptom dimensions and their relationship to functioning in World Trade Center responders. Psychiatry Research. Published online: 21 09 2013 . doi:10.1016/j.psychres.2013.08.052.
Satorra A, Bentler PM (2001). A scaled difference chi-square test statistic for moment structure analysis. Psychometrika 66, 507514.
Schell TL, Marshall GN, Jaycox LH (2004). All symptoms are not created equal: the prominent role of hyperarousal in the natural course of posttraumatic psychological distress. Journal of Abnormal Psychology 113, 189197.
Schindel-Allon I, Aderka IM, Shahar G, Stein M, Gilboa-Schechtman E (2010). Longitudinal associations between post-traumatic distress and depressive symptoms following a traumatic event: a test of three models. Psychological Medicine 40, 16691678.
Schwarz G (1978). Estimating the dimension of a model. Annals of Statistics 6, 461464.
Simms LJ, Watson D, Doebbeling BN (2002). Confirmatory factor analyses of posttraumatic stress symptoms in deployed and nondeployed veterans of the Gulf War. Journal of Abnormal Psychology 111, 637647.
Solomon Z, Horesh D, Ein-Dor T (2009). The longitudinal course of posttraumatic stress disorder symptom clusters among war veterans. Journal of Clinical Psychiatry 70, 837843.
Soo J, Webber MP, Gustave J, Lee R, Hall CB, Cohen HW, Kelly KJ, Prezant DJ (2011). Trends in probable PTSD in firefighters exposed to the World Trade Center disaster, 2001–2010. Disaster Medicine and Public Health Preparedness 5 (Suppl. 2), S197S203.
Stellman JM, Smith RP, Katz CL, Sharma V, Charney DS, Herbert R, Moline J, Luft BJ, Markowitz S, Udasin I, Harrison D, Baron S, Landrigan PJ, Levin SM, Southwick S (2008). Enduring mental health morbidity and social function impairment in World Trade Center rescue, recovery, and cleanup workers: the psychological dimension of an environmental health disaster. Environmental Health Perspectives 116, 12481253.
Strawn JR, Geracioti TDJ (2008). Noradrenergic dysfunction and the psychopharmacology of posttraumatic stress disorder. Depression and Anxiety 25, 260271.
Thompson KE, Vasterling JJ, Benotsch EG, Brailey K, Constans J, Uddo M, Sutker PB (2004). Early symptom predictors of chronic distress in Gulf War veterans. Journal of Nervous and Mental Disease 192, 146152.
Vaiva G, Ducrocq F, Jezequel K, Averland B, Lestavel P, Brunet A, Marmar CR (2003). Immediate treatment with propranolol decreases posttraumatic stress disorder two months after trauma. Biological Psychiatry 54, 947949.
Wang L, Li Z, Shi Z, Zhang J, Zhang K, Liu Z, Elhai JD (2011 a). Testing the dimensionality of posttraumatic stress responses in young Chinese adult earthquake survivors: further evidence for ‘dysphoric arousal’ as a unique PTSD construct. Depression and Anxiety 28, 10971104.
Wang L, Zhang J, Shi Z, Zhou M, Li Z, Zhang K, Liu Z, Elhai JD (2011 b). Comparing alternative factor models of PTSD symptoms across earthquake victims and violent riot witnesses in China: evidence for a five-factor model proposed by Elhai et al (2011). Journal of Anxiety Disorders 25, 771776.
Wang M, Armour C, Li X, Dai X, Zhu X, Yao S (2013 a). The factorial invariance across gender of three well-supported models: further evidence for a five-factor model of posttraumatic stress disorder. Journal of Nervous and Mental Disease 201, 145152.
Wang PS, Lane M, Olfson M, Pincus HA, Wells KB, Kessler RC (2005). Twelve-month use of mental health services in the United States: results from the National Comorbidity Survey Replication. Archives of General Psychiatry 62, 629640.
Wang R, Wang L, Li Z, Cao C, Shi Z, Zhang J (2013 b). Latent structure of posttraumatic stress disorder symptoms in an adolescent sample one month after an earthquake. Journal of Adolescence 36, 717725.
Watson D (2005). Rethinking the mood and anxiety disorders: a quantitative hierarchical model for DSM-V. Journal of Abnormal Psychology 114, 522536.
Weathers F, Litz B, Herman D, Huska J, Keane T (1993). The PTSD Checklist (PCL): reliability, validity, and diagnostic utility. Paper presented at the Annual Convention of the International Society for Traumatic Stress Studies, San Antonio, TX ( Accessed November 2013.
Webber MP, Glaser MS, Weakley J, Soo J, Ye F, Zeig-Owens R, Weiden MD, Nolan A, Aldrich TK, Kelly K, Prezant D (2013). Physician-diagnosed respiratory conditions and mental health symptoms 7–9 years following the World Trade Center disaster. American Journal of Industrial Medicine 54, 661671.
Wisnivesky JP, Teitelbaum S, Todd A, Boffetta P, Crane M, Dellenbaugh C, Harrison D, Herbert R, Jeon Y, Kaplan J, Levin S, Luft B, Markowitz S, Moline J, Pietrzak RH, Shapiro M, Southwick SM, Stevenson L, Udasin I, Wallenstein S, Landrigan P (2011). Long persistence of multiple illnesses in September 11 responders. Lancet 378, 888897.
Yufik T, Simms LJ (2010). A meta-analytic investigation of the structure of posttraumatic stress disorder symptoms. Journal of Abnormal Psychology 119, 764776.
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