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The Police Stress and Health Program // Research
Research Findings
While our research is ongoing and far from done, over the years, the Police Stress and Health Program has collected a wealth of information that has given us a glimpse into how stress affects the health and lives of law enforcement professionals and their families.
Below is a summary of our research findings to date, listed in the order in which they developed. Published articles have been cited where relevant and a complete list of references is available for your convenience at the bottom of the page.
Should you have any questions about the information provided here or anywhere on this website, please do not hesitate to contact us.
Predictors of Distress in Emergency Services Personnel to the 1989 Bay Area Earthquake
Our work on police stress and health began more than a decade ago. The loss of life and devastation resulting from the 1989 Loma Prieta Earthquake, and the heavy toll exacted on law enforcement and other first responders, motivated us to conduct a study of emergency services personnel.
We evaluated 154 EMS workers involved in the 1989 Interstate 880 freeway collapse during the San Francisco Bay area earthquake, and 213 counterparts from the Bay area and from San Diego. Our goal was to determine who was at greater risk for PTSD. We found that greater life threat, lower social supports, greater personal adjustment difficulties, and fewer years of experience placed EMS workers at greater risk.
We also found that one of the most robust predictors was a profound sense of unreality at the time of critical incident occurrence, as though what was happening was unreal and was like watching a movie or a play. We call this phenomenon peritraumatic dissociation (C.R. Marmar, D.S. Weiss, W.E. Schlenger, J.A. Fairbank, B.K .Jordan, R.A Kulka, & Hough, R.L. Peritraumatic dissociation and post-traumatic stress in male Vietnam theater veterans. American Journal of Psychiatry, 1994, 151:902-907; Weiss, D.S., Marmar, C.R., Metzler, T.J., Ronfeldt, H.M. Predicting symptomatic distress in emergency services personnel. J Consult Clin Psychol 1995; 63(3):361-8).
The practical value of this work has been to assist law enforcement in identification of those at greatest need for immediate assistance following critical incident exposure.
Predictors of Dissociation During Critical Incident Exposure in Emergency Services Personnel
We next investigated why it is that some police officers and other first responders in our Loma Prieta Earthquake sample were more prone to experience acute dissociative responses at the time of critical incident exposure, placing them at greater risk for PTSD.
We found that first responders who are shy, inhibited, uncertain about their identity, or reluctant to take leadership roles, who believe their fate is determined by factors beyond their control, and who cope with critical incident trauma by emotional suppression (“sucking it up”) and wishful thinking are at higher risk for acute dissociative responses to trauma and subsequent PTSD (Marmar, C.R., Weiss, D.S., Metzler, T.J., Delucchi, K. Characteristics of emergency services personnel related to peritraumatic dissociation during critical incident exposure. Am J Psychiatry 1996; 153 (7 Suppl):94-102). These findings have implications for selection, training, and psychological support of first responders.
In this study we found that a notable nine percent of the sample were characterized as having symptom levels typical of psychiatric outpatients. This is one of the first well designed large scale studies using reliable measures to document that approximately one in ten first responders has significant psychological distress that persists for months to years following extreme stress exposure. Our study, and others employing similar designs, have influenced law enforcement and other EMS agencies to invest in greater mental health screening and care following large scale man made and natural disasters.
Time Course of PTSD Symptoms in Emergency Services Personnel
In the same data set we also asked whether different groups of first responders responded differently to critical incidents. We found that EMT/Paramedics reported higher peritraumatic dissociation compared with Police, and EMT/Paramedics and California road workers reported higher levels of psychological symptoms compared with Police and Fire personnel. (Marmar, C.R., Weiss, D.S., Metzler, T.J., Ronfeldt, H.M., Foreman, C. Stress responses of emergency services personnel to the Loma Prieta earthquake Interstate 880 freeway collapse and control traumatic incidents. J Trauma Stress 1996; 9(1):63-85).
These data point to the relative resiliency of professional first responders including police, and to the vulnerability of groups such as construction workers who have little training to prepare for large scale disasters. A recent study of Con Edison utility workers who responded to gas, electrical and steam problems created by the WTC attacks, endangering their own lives and exposing them to bodies and body parts, replicated our findings.
We next asked whether PTSD symptoms in these EMS workers would persist or resolve with the passage of time and support of co-workers, family and friends. We administered questionnaires first at 1.9 years and again at 3.5 years after the freeway collapse (Marmar, C., Weiss, D., Metzler, T., Delucchi, K., Best, S., Wentworth, K. Longitudinal course and predictors of continuing distress following critical incident exposure in emergency services personnel. J Nerv Ment Dis 1999; 187(1):15-22).
Despite modest symptom improvement from the first to second evaluation, we found that rescue workers, particularly those with more catastrophic exposure and those prone to greater dissociation at the time of the critical incident, are at risk for chronic symptomatic distress, lasting nearly four years after the earthquake.
Our study had been influential in dispelling the belief that tincture of time usually cures PTSD. While a majority of those in law enforcement are resilient and fortunately do not develop psychological problems after critical incidents, and among those who are initially distressed many will recover in the first months, an important minority develops distress lasting 12 to 18 months. This more vulnerable group is unlikely to recover 4 or more years later without the benefit of effective treatment.
Terror, Horror and Helplessness During Critical Incidents in Police Officers
Building on the above findings with EMS workers, we next conducted a cross-sectional study of 741 police officers from the New York, Oakland and San Jose Police Departments, and 301 matched controls including both genders. The aim was to determine risk and resilience factors for critical incident related PTSD.
We first focused on the level of terror, horror, helplessness, panic, grief and other experiences of emotional distress at the time of an officer’s self–identified worst duty-related traumatic stressor. The sample included Caucasians, Hispanics and African Americans officers, with oversampling for female and minority officers, exposed to a wide range of critical incidents.
We developed a 13-item self-report measure, the Peritraumatic Distress Inventory (PDI), as a way of obtaining a quantitative measure of the level of distress experienced during and immediately after a traumatic event. The PDI has good reliability and validity. We found that officers with higher scores on the PDI, reflecting greater emotional distress during critical incident exposure, had greater PTSD symptoms (Brunet, A., Weiss, D., Metzler, T., Best, S., Neylan, T., Rogers, C., Fagan, J. & Marmar, C. The Peritraumatic Distress Inventory: a proposed measure of PTSD Criterion A2. Am J Psychiatry 2001; 158(9):1480-5).
This finding has immediate practical value for law enforcement. Those officers with high distress, including panic reactions, at the time of critical incident exposure are those in greatest need of immediate psychological support. Immediate care is directed at countering panic by restoring a sense of safety and control.
Those with high levels of emotional distress at the time of critical incident exposure, and in the first 24 to 72 hours after are also the group in greatest need of support and at the same time those that must be approached with the greatest caution when intervening to provide support. They are at risk for adverse effects of debriefing approaches that emphasize emotional retelling of the incident, if exploring raw feelings occurs before the officer has been able to regain emotional composure, they may have the unintended effect of prolonging panic reactions.
In a pilot study of civilian accident victims we have reported that a brief course of an adrenaline blocking medication, propranolol, is promising for controlling immediate panic reactions and reducing PTSD symptoms two months later.
Role of Gender and Ethnicity in Explaining Posttraumatic Stress in Police Officers
We next assessed for ethnic and gender differences in duty-related symptoms of posttraumatic stress disorder (PTSD) in this sample of 741 New York Police Department (NYPD), Oakland Police Department (OPD) and San Jose Police Department (SJPD) officers.
We found that self-identified Hispanic American officers evidenced greater PTSD symptoms than both self-identified European American and self-identified African American officers. These effects were small in size but they persisted even after controlling for differences in other relevant variables. We found no gender differences in PTSD symptoms (Pole, N., Best, S., Weiss, D., Metzler, T., Liberman, A., Fagan, J., Marmar, C. Effects of gender and ethnicity on duty-related posttraumatic stress symptoms among urban police officers. J Nerv Ment Dis. 2001;189(7):442-8).
Our findings are of note because: (a) they replicate a previous finding of greater PTSD among Hispanic American military personnel and (b) they fail to replicate the typical finding of greater rates of PTSD symptoms among women in the community. Female police officers are as highly exposed to critical incidents and as resilient as their male colleagues.
In an attempt to further understand the role of Hispanic ethnicity in vulnerability to PTSD, we identified predictors of PTSD symptom severity that distinguished Hispanic police officers (n = 189) from their non-Hispanic Caucasian (n = 317) and Black (n = 162) counterparts and modeled them to explain the elevated Hispanic risk for PTSD.
We found that greater peritraumatic dissociation, greater wishful thinking and self-blame coping, lower social support, and greater perceived racism were important variables in explaining the elevated risk for PTSD symptom severity among Hispanic officers (Pole, N., Best, S., Metzler, T., Marmar, C., Weiss, D., & Fagan, J. Explanations for Hispanic ethnicity as a correlate of PTSD symptoms in urban police officers. Cultural Diversity and Ethnic Minority Psychology, In Press).
These results may be important for prevention of PTSD in a rapidly growing ethnic group in law enforcement.
Role of Routine Work Stress and Critical Incident Exposure in Explaining Posttraumatic Stress in Police Officers
While there has been a great deal of interest in the role of critical incident stress in law enforcement, there has been less attention to the effects of routine work environment stress. We developed the Work Environment Inventory (WEI) to assess exposure to routine work stressors, including negative attitudes of the public and judiciary toward law enforcement, poor physical conditions, ethnic and gender discrimination, and sexual harassment.
In our cross-sectional study of 741 New York and Bay Area officers, exposure to routine work stressors strongly predicted general psychological distress, and was a surprisingly strong predictor of posttraumatic stress symptoms related to officers’ most traumatic career incident. (Liberman, A., Best, S., Metzler, T., Fagan, J.A., Weiss, D. and Marmar, C. Routine occupational stress and psychological distress in police. Policing: An International Journal of Police Strategies and Management 2002; 25(2): 421-439).
Our work has focused awareness in law enforcement that efforts to ensure a positive work climate not only improve morale but also hold promise for increasing resilience to critical incidents.
Patterns and Predictors of Sleep Disturbance in Police Officers
Police officers face many stressors that may negatively impact sleep quality. In this data set of 741 New York and Bay Area police officers, we examined the effects of critical incident exposure and routine work environment stressors on sleep quality, controlling for the effects of work shift schedule.
Police officers on both variable and stable day shifts reported significantly worse sleep quality and less average sleep time than civilian control groups. A large percentage of police officers report disturbances in subjective sleep quality. Within police officers, greater critical incident exposure was associated with more nightmares but only weakly associated with generalized insomnia. In contrast, the stress from officers’ general work environment was strongly associated with generalized insomnia (Neylan, T., Metzler, T., Best, S., Weiss, D., Fagan, J., Liberman, A., Rogers, C., Vedantham, K., Brunet, A., Lipsey, T., and Marmar. C. Critical incident exposure and sleep quality in police officers. Psychosom Med 2002; 64(2):345-52).
Disturbed Sleep Explains Physical Health Problems in Police Officers
Earlier studies with civilian samples demonstrated that chronic sleep disturbances contribute to poor physical health. Posttraumatic stress symptoms have also been associated with increased health problems across numerous studies.
In this sample of 741 New York and Bay Area police officers we found that the relationship between posttraumatic stress symptoms and self-reported physical health problems was explained by sleep problems (Mohr, D., Vedantham, K., Neylan, T., Metzler, T., Best, S., and Marmar, C. The mediating effects of sleep in the relationship between traumatic stress and health symptoms in urban police officers. Psychosom Med 2003; 65(3):485-9).
These findings have been helpful to law enforcement by clarifying the types, causes and unexpectedly high rates of sleep disturbances, in an occupation placing high demands on alertness for accurate threat appraisal and rapid reaction times, and by drawing attention to the health risks of chronic sleep disturbances.
Patterns and Predictors of Alcohol Use in Police Officers
In our sample of 741 New York and Bay Area police officers, we found adverse lifetime consequences from alcohol use in 18.1% of males and 15.9% of females, excessive drinking in the past week in 11.0 % of males and 16.3 % of females, with 7.8 % of the entire sample meeting criteria for lifetime alcohol abuse or dependence. Women officers had patterns of alcohol use similar to male officers, and substantially greater than females in the general population. Unexpectedly, greater critical incident exposure and current PTSD symptoms were not associated with greater current alcohol use.
For the entire sample, lower education, greater routine work stress, and greater current psychiatric symptoms were related to greater lifetime adverse consequences from alcohol use. Lower education was associated with greater alcohol use in male but not female officers, and greater routine work stress related to lower current alcohol use in female officers (Ballenger, J., Delucchi, K., Mohr, D., Weiss, D., Fagan, J., & Marmar, C. Patterns and predictors of alcohol use in male and female urban police officers. Psychology of Addictive Behaviors, In Press).
Our work is one of the first large scale studies using reliable assessments to support the need in law enforcement to prioritize alcohol abuse services.
Critical Incident History Questionnaire: Measuring Traumatic Exposure in Police Officers
We have also developed a 34-item self-report measure, the Critical Incident History Questionnaire, that yields a quantitative measure of total career exposure to potentially traumatic duty-related events.
Data from our sample of New York, and Bay Area officers showed that officers were in agreement about how difficult it typically would be to cope with each of the 34 incidents. As expected, total career exposure increased with years of service, and was related to PTSD symptoms associated with the officer’s worst duty-related critical incident (Weiss, D., Brunet, A., Best, S., Metzler, T., Liberman, A., Rogers, C., Neylan, T., Fagan, J., & Marmar, C.. The critical incident history questionnaire: A method for measuring total cumulative exposure to critical incidents, In Submission).
Our measure has been of value to law enforcement in comprehensively delineating the patterns of critical incident exposure across an officer’s career.
Impact of the World Trade Center Attacks on the New York Police Department
One group deeply impacted by the World Trade Center Attacks was the New York Police Department. The uniquely traumatic circumstances of the attacks and subsequent recovery operations occurred against a background of high levels of ongoing routine work environment and critical incident stressors, including threats of future terrorist attacks.
We conducted a prospective cohort study of New York police officers, surveying 541 form our sample of 741 approximately a year and half before 9/11, and reassessing 301 of these officers a year and a half after 9/11.
Prior to 9/11, 3.5% of NYPD officers were estimated to have PTSD and 3.5 % partial PTSD; this compares with 8.8% with PTSD and 15.0% with partial PTSD after 9/11. Compared to pre 9/11, NYPD officers were also found to have increases in anxiety, depression, sleep disturbances, and marital adjustment problems.
The strongest predictors of 9/11 related PTSD symptoms were greater PTSD symptoms prior to 9/11, greater dissociation and emotional distress during 9/11 exposure, and both greater negative life events and lower social support after 9/11 (C.R. Marmar, T. Metzler, C. Chemtob, K. Delucchi, A.Liberman, J. Fagan, D. S. Weiss, D. Mohr , T.Neylan M.D., & S. Best. Impact of the World Trade Center Attacks on the New York City Police Department: A Prospective Study, In Preparation).
Our findings represent the only available data on law enforcement before and after a large scale terrorist attack, and reveal a large and lasting increase in PTSD symptoms.
Police Officers with PTSD Symptoms Have Greater Acoustic Startle Reactions
More recently, our work has focused on biological factors associated with vulnerability and resilience to posttraumatic stress disorder. We initially established a laboratory in San Francisco to acquire heart rate, skin conductance, muscle tone, and salivary stress hormones including adrenaline and cortisol.
We have measured biological responses of police officers after critical incident exposure to loud startling tones and academy recruits prior to critical incident exposure to startling tones and vivid portrayals of real life critical incidents, and in both groups measured awakening cortisol before and after administering a synthetic steroid.
We first studied responses to startling sounds under low, medium, and high threat conditions in 55 Bay Area police officers who reported a range of PTSD symptoms. Greater PTSD symptom severity was related to greater physiologic responses to startling tones under conditions of ambiguous threat (Pole, N., Neylan, T., Best, S., Orr, S., & Marmar, C. Fear-potentiated startle and posttraumatic stress symptoms in urban police officers. Journal of Traumatic Stress 2003; 16(5), 471-479).
We also found that lower levels of cortisol on awakening were related to greater PTSD symptoms (Neylan, T., Brunet, A., Pole, N., Best, S., Metzler, T., Yehuda, R., & Marmar, C. PTSD symptoms predict cortisol levels in active duty police officers. Psychoneuroendocrinology, In Press).
Our results are of value to law enforcement by contributing to the search for objective biological markers of posttraumatic stress in greater eye blink and skin conductance reactions to loud tones and in lower levels of salivary cortisol on awakening. As theses biological markers are refined, they hold promise for understanding who is at risk for PTSD, informing new treatments and adjudicating disability claims.
The Role of Childhood Trauma in Explaining Stress Reactivity Of Police Academy Recruits
We have recently initiated a prospective study of 500 New York and Bay Area police academy recruits, who will be assessed during training and followed for the first two years of police service.
We have expanded our biological research with laboratories in New York and San Francisco, both assessing heart rate, skin conductance, eyeblink response, salivary stress hormones including adrenaline and cortisol, diurnal sleep patterns and reaction times. We have established control systems in San Francisco, utilizing internet resources to maintain real time calibration, for managing biological and clinical assessments in New York. We have manualized the control procedures, establishing a process that can be replicated in London and elsewhere.
The primary aim of this study is to determine biological and behavioral predictors of resilience and vulnerability to critical incident stress prior to critical incident exposure. Along with twin studies, prospective studies are the strongest designs to clarify if abnormalities in PTSD are a result of exposure or are vulnerabilities that are heritable or the product of early life experience.
First results from our prospective study focus on 76 male and female police academy recruits, average age 28 years, exposed to a 20 minute video depicting real-life officers exposed to highly stressful incidents. Salivary cortisol and an adrenaline metabolite were collected at baseline, immediately after the video, and twenty minutes after the video. Childhood trauma prior to age 14 was assessed with the Life Stressor Checklist.
Police academy recruits with childhood trauma histories had an increased adrenaline response to psychological stress (C. Otte, T. C. Neylan, N. Pole, T. Metzler, S. Best, C. Henn-Haase, R. Yehuda, C. R. Marmar. Association between childhood trauma and catecholamine response to psychological stress in police academy recruits. Biological Psychiatry, In Press).
We next exposed the first 101 academy recruits, including the 76 who participated in the critical incident simulation video task, to startling sounds, while assessing their heart rate (HR), skin conductance (SC), eyeblink electromyogram (EMG), and danger/safety emotion responses.
When compared to their unexposed counterparts (n = 75), cadets with childhood trauma (n = 26) produced higher EMG, SC and HR responses (N. Pole T. C. Neylan, C. Otte, T.J. Metzler, S.R. Best, C. Henn-Haase, and C.R. Marmar. Effects of Childhood Trauma on Fear-Potentiated Startle Reactivity: A Study of Police Academy Cadets, In Preparation).
We will follow these recruits for the first two years of police service and determine if greater adrenaline responses during a critical incident simulation video during training, and greater heart rate, muscle contraction and skin conductance to startling sounds, reflecting greater stress reactivity, predict greater PTSD symptoms following duty-related critical incident exposure.
Marmar C.R., Weiss D.S., Schlenger W.E., Fairbank J.A., Jordan B.K., Kulka R.A., & Hough, R.L. Peritraumatic dissociation and post-traumatic stress in male Vietnam theater veterans. American Journal of Psychiatry 1994; 151:902-907.
Weiss, D.S., Marmar, C.R., Metzler, T.J., Ronfeldt, H.M. Predicting symptomatic distress in emergency services personnel. J Consult Clin Psychol, 1995; 63(3):361-8.
Marmar, C.R., Weiss, D.S., Metzler, T.J., Delucchi, K. Characteristics of emergency services personnel related to peritraumatic dissociation during critical incident exposure. Am J Psychiatry 1996; 153 (7 Suppl):94-102.
Marmar, C.R., Weiss, D.S., Metzler, T.J., Ronfeldt, H.M., Foreman, C. Stress responses of emergency services personnel to the Loma Prieta earthquake Interstate 880 freeway collapse and control traumatic incidents. J Trauma Stress 1996; 9(1):63-85.
Marmar, C., Weiss, D., Metzler, T., Delucchi, K., Best, S., Wentworth, K. Longitudinal course and predictors of continuing distress following critical incident exposure in emergency services personnel. J Nerv Ment Dis 1999; 187(1):15-22.
Brunet, A., Weiss, D., Metzler, T., Best, S., Neylan, T., Rogers, C., Fagan, J. & Marmar, C. The Peritraumatic Distress Inventory: a proposed measure of PTSD Criterion A2. Am J Psychiatry 2001; 158(9):1480-5).
Pole, N., Best, S., Weiss, D., Metzler, T., Liberman, A., Fagan, J., Marmar, C. Effects of gender and ethnicity on duty-related posttraumatic stress symptoms among urban police officers. J Nerv Ment Dis. 2001; 189(7):442-8.
Liberman, A., Best, S., Metzler, T., Fagan, J.A., Weiss, D. and Marmar, C. Routine occupational stress and psychological distress in police. Policing: An International Journal of Police Strategies and Management 2002; 25(2): 421-439.
Neylan, T., Metzler, T., Best, S., Weiss, D., Fagan, J., Liberman, A., Rogers, C., Vedantham, K., Brunet, A., Lipsey, T., and Marmar. C. Critical incident exposure and sleep quality in police officers. Psychosom Med 2002; 64(2):345-52.
Mohr, D., Vedantham, K., Neylan, T., Metzler, T., Best, S., and Marmar, C. The mediating effects of sleep in the relationship between traumatic stress and health symptoms in urban police officers. Psychosom Med 2003; 65(3):485-9).
Pole, N., Neylan, T., Best, S., Orr, S., & Marmar, C. Fear-potentiated startle and posttraumatic stress symptoms in urban police officers. Journal of Traumatic Stress 2003; 16(5), 471-479.
Neylan, T., Brunet, A., Pole, N., Best, S., Metzler, T., Yehuda, R., & Marmar, C. PTSD symptoms predict cortisol levels in active duty police officers. Psychoneuroendocrinology, In Press.
Otte C., Neylan T., Pole N., Metzler T., Best S., Henn-Haase C., Yehuda R., and C. R. Marmar. Association between childhood trauma and catecholamine response to psychological stress in police academy recruits. Biological Psychiatry, In Press.
Pole, N., Best, S., Metzler, T., Marmar, C., Weiss, D., & Fagan, J. Explanations for Hispanic ethnicity as a correlate of PTSD symptoms in urban police officers. Cultural Diversity and Ethnic Minority Psychology, In Press.
Ballenger, J., Delucchi, K., Mohr, D., Weiss, D., Fagan, J., & Marmar, C. Patterns and predictors of alcohol use in male and female urban police officers. Psychology of Addictive Behaviors, In Press.Weiss, D., Brunet, A., Best, S., Metzler, T., Liberman, A., Rogers, C., Neylan, T., Fagan, J., & Marmar, C. The critical incident history questionnaire: A method for measuring total cumulative exposure to critical incidents, In Submission.
Marmar C.R., Metzler T., Chemtob C., Delucchi K., Liberman A., Fagan J., Weiss D.S., Mohr D., Neylan T., & S. Best. Impact of the World Trade Center Attacks on the New York City Police Department: A Prospective Study, In Preparation.
Pole N., Neylan T., Otte C., Metzler T., Best S., Henn-Haase C., and C.R. Marmar. Effects of Childhood Trauma on Fear-Potentiated Startle Reactivity: A Study of Police Academy Cadets, In Preparation.
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