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A 20-year longitudinal cohort study of post-traumatic stress disorder in World Trade Center responders

Nature Mental Health volume 3, pages 789–802 (2025)Cite this article

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Abstract

Post-traumatic stress disorder (PTSD) is a debilitating condition with serious implications for mental and physical health. Although previous studies have documented PTSD prevalence and short-term trajectories, detailed examination of long-term symptom patterns remains limited, especially in large cohorts. This study investigates 20-year PTSD symptom trajectories in World Trade Center responders, constituting one of the largest and longest studies of PTSD to date. We aimed to answer the following questions. How stable are symptoms? What is the average trajectory? What are atypical trajectories? How quickly do symptoms improve and worsen? Does symptom course differ across demographics or predict functional impairments or mental health care utilization? Data include 81,298 observations from 12,822 responders. Symptoms were stable in the short term but changed significantly over two decades, peaking over a decade after exposure and declining modestly thereafter. Demographic differences in average trajectories were small. The median time before symptoms improved was 8–10 years for PTSD cases (median = 8.88; 95% confidence interval, 8.01–9.79). Most experienced improvement after a decade but approximately 10% reported elevated symptoms two decades after trauma. Changes in symptoms predicted higher functional impairments and mental health care utilization. Our findings highlight the enduring impact of PTSD among World Trade Center responders, with substantial variability in individual trajectories. Despite overall modest declines, a subset remained highly symptomatic, underscoring the need for continued treatment. These results emphasize the importance of long-term monitoring and highlight the need for tailored treatment strategies for trauma-exposed populations.

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Fig. 1: Annual prevalence of clinically elevated symptoms, temporal stability and mean predicted trajectory of PTSD symptom severity stratified by PTSD diagnosis.
Fig. 2: Predicted trajectories of PTSD symptom severity stratified by PTSD diagnosis and trajectory severity quantiles.
Fig. 3: Time to improvement and deterioration of PTSD symptoms.
Fig. 4: Crude prevalence of functional impairments by deciles of predicted change in PTSD symptoms.
Fig. 5: Use of mental health care in 2022 by deciles of predicted change in PTSD symptoms.

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Data availability

Data not provided in the Article because of space limitations are not publicly shared due to ethical considerations. Study participants provided consent for their data to be analyzed only by study personnel. To respect the autonomy and privacy of the study participants, the data underlying the reported results will be made available to qualified investigators whose proposed use of the data has been approved by an internal review committee and the Institutional Review Board at Stony Brook University. This access will be granted up to 4 years after publication of this study, following rigorous de-identification of sensitive information. Requests for data access will be reviewed and a response will be provided within 60 days of submission.

Code availability

The analysis code is publicly available at https://osf.io/p7sx2/.

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Acknowledgements

Data collection was funded by CDC 2011‐200‐39361 (awarded to B.J.L.), U01OH011864 (awarded to R.K. and M.A.W.) and the SUNY Research Foundation. F.D.M. was awarded and partially funded by R21AG074705‐01. We thank the WTC responders from the General Responder Cohort whose participation was integral to this work.

Author information

Authors and Affiliations

  1. Program in Public Health and Department of Family, Population, and Preventive Medicine, Renaissance School of Medicine, Stony Brook University, New York, NY, USA

    Frank D. Mann & Sean A. P. Clouston

  2. Department of Medicine, Renaissance School of Medicine, Stony Brook University, New York, NY, USA

    Frank D. Mann & Benjamin J. Luft

  3. Department of Psychology, Rosalind Franklin University of Medicine and Science, Chicago, IL, USA

    Monika A. Waszczuk

  4. Department of Psychiatry, Renaissance School of Medicine, Stony Brook University, New York, NY, USA

    Scott Feltman, Joseph E. Schwartz, Evelyn J. Bromet & Roman Kotov

  5. Department of Psychology, University of Texas at Dallas, Richardson, TX, USA

    Camilo J. Ruggero

  6. National Center for PTSD, VA Boston Healthcare System, and Department of Psychiatry, Chobanian & Avedisian School of Medicine, Boston University, Boston, MA, USA

    Brian P. Marx

  7. World Trade Center Program, Renaissance School of Medicine, Stony Brook University, New York, NY, USA

    Benjamin J. Luft

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Contributions

F.D.M. analyzed the data in consultation with R.K. F.D.M. drafted the manuscript. B.J.L., R.K. and M.A.W. obtained funding for the study. M.A.W., S.A.P.C., S.F., C.J.R., B.P.M., J.E.S., E.J.B. and B.J.L. provided critical revisions and approved the final version of the Article.

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Correspondence to Frank D. Mann.

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Nature Mental Health thanks Shane Adams, Clare Henn-Haase and Christopher Layne for their contribution to the peer review of this work.

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Extended data

Extended Data Fig. 1 Observed trajectories of PTSD symptoms for WTC responders.

Top left panel, individual trajectories are plotted for the full sample. The remaining panels plot subsamples of n = 500 observations without replacement with dashed gray lines indicating quadratic trends and orange regions denoting 95% confidence bands.

Extended Data Fig. 2 Average predicted trajectories of PTSD symptoms from quadratic and cubic mixed effects models.

The top and bottom panels plot average quadratic and cubic trends, respectively. Blue “X”s indicates annual means and dashed vertical lines denote plus and minus 2 times the standard error of the mean. Sample sizes and descriptive statistics are reported in Table 1.

Extended Data Fig. 3 Observed scores and predicted trajectories for individual responders diagnosed with PTSD from parametric and generalized mixed effect models.

Observed scores (blue circles) from 20 responders with a lifetime diagnosis of PTSD and 15 or more observations are plotted with predicted trends from a linear mixed effect model (dashed red line) and a generalized mixed effect model with Gamma distribution and log link (dashed black line).

Extended Data Fig. 4 Average predicted trend in PCL scores from the preferred generalized mixed effect model stratified by baseline year of data collection, the number of completed assessments, and the average interval between assessments.

a, Each line depicts the average predicted trend for responders who completed their baseline assessment during a given year. b, Each line depicts the average predicted trend for responders who completed different numbers of assessments. c, Each line depicts the average predicted trend for responders with different average intervals of time between assessments. In all panels, shaded regions depicting 95% confidence bands.

Extended Data Fig. 5 Distributions of changes in observed PCL scores across increasing time lags stratified by baseline PCL score.

Given intercept-slope correlations, plots were stratified by observed PCL scores at in-take. Created using the ‘ggridges’ package, density plots of observed changes in PCL scores (x axis) across increasing time lags (y axis) are plotted and grouped by observed PCL scores at first visit (top label of each panel).

Extended Data Fig. 6 Average predicted trajectory of PTSD symptoms by demographic factors.

a, Age-group differences in the average predicted trajectory. b, Sex differences in the average predicted trajectory. c, Race/ethnicity differences in the average predicted trajectory. d, Occupational differences in the average predicted trajectory. In all panels, shaded regions denote 95% confidence bands. Effects of demographic factors on levels of symptoms (that is, intercepts) are statistically significant at two-tailed FDR-adjusted q-values < 0.05 using the Benjamini–Hochberg procedure, and effects on rates of change (that is linear and quadratic slopes) are not statistically significant (q-values > 0.10).

Extended Data Fig. 7 Average predicted trajectory of PTSD symptoms by traumatic exposures.

Average predicted trajectories are depicted for responders who arrived early or late to the WTC following the 9/11 attacks (a), who did or did not witness the collapse of the Twin Towers (b), reported being caught in the dust cloud (c), exposed to blood or bodily fluids (d), exposed to human remains (e), slept at Ground Zero (f), knew someone who was injured (g), and knew someone who died (that is, experienced traumatic bereavement; h). In all panels, shaded regions denote 95% confidence bands. The effects of each traumatic exposures on levels of symptoms (that is, intercepts) are statistically significant at FDR-adjusted q-values < 0.001 using the Benjamini–Hochberg procedure, and the effects of each traumatic exposures on rates of change (that is, linear and quadratic slopes) are not statistically significant (q-values > 0.10).

Extended Data Fig. 8 Prediction of functional impairments in 2022 by deciles of predicted change in PTSD symptoms.

Circles denote adjusted risk ratios from robust quasi-Poisson regressions predicting impairment in mental function and physical function, indicated by a mental component score (MCS < 40) or physical component score (PCS < 40) derived from the SF-12 more than one standard deviation below the normed average, controlling for the effects of demographic factors and baseline PTSD symptom severity (Supplementary Tables 13 and 14). Vertical bars denote 95% confidence intervals calculated using heteroscedasticity-consistent (HC1) standard errors.

Extended Data Fig. 9 Prediction of mental health care services in 2022 by deciles of predicted change in PTSD symptoms.

Circles denote linear regression coefficients predicting log transformed expenditures (a) and relative risk ratios from robust quasi-Poisson regressions (b,c), adjusted for the effects of demographic factors and baseline PTSD symptom severity (Supplementary Tables 15–17). Vertical bars denote 95% confidence intervals calculated using heteroscedasticity-consistent (HC1) standard errors.

Extended Data Table 1 Descriptive statistics and estimates of internal consistency for PCL-S across waves of data collection for the full sample and PTSD cases
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Supplementary information

Supplementary Information

Supplementary methods, Tables 1–18 and Figs. 1–12.

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Mann, F.D., Waszczuk, M.A., Clouston, S.A.P. et al. A 20-year longitudinal cohort study of post-traumatic stress disorder in World Trade Center responders. Nat. Mental Health 3, 789–802 (2025). https://doi.org/10.1038/s44220-025-00419-1

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