Nnamdi Pole

The Psychophysiology of Posttraumatic Stress Disorder: A Meta-Analysis.

This meta-analysis of 58 resting baseline studies, 25 startle studies, 17 standardized trauma cue studies, and 22 idiographic trauma cue studies compared adults with and without posttraumatic stress disorder (PTSD) on psychophysiological variables: facial electromyography (EMG), heart rate (HR), skin conductance (SC), and blood pressure. Significant weighted mean effects of PTSD were observed for HR (r = .18) and SC (r = .08) in resting baseline studies; eyeblink EMG (r = .13), HR (r = .23), and SC habituation slope (r = .21) in startle studies; HR (r = .27) in standardized trauma cue studies; and frontalis EMG (r = .21), corrugator EMG (r = .34), HR (r = .22), and SC (r = .19) in idiographic trauma cue studies. The most robust correlates of PTSD were SC habituation slope, facial EMG during idiographic trauma cues, and HR during all study types. Overall, the results support the view that PTSD is associated with elevated psychophysiology. However, the generalizability of these findings is limited by characteristics of the published literature, including its disproportionate focus on male veterans and neglect of potential PTSD subtypes.

Predictors of Posttraumatic Stress in Police and Other First Responders

Abstract:  We provide an overview of previous research conducted by our group on risk and resilience factors for PTSD symptoms in police and other first responders. Based on our work, the findings of other investigators on individual differences in risk for PTSD, and drawing on preclinical studies fear conditioning and extinction, we propose a conceptual model for the development of PTSD symptoms emphasizing the role of vulnerability and resilience to peritraumatic panic reactions. We tested this conceptual model in a cross‐sectional sample of police officers (n= 715). Utilizing an hierarchical linear regression model we were able to explain 39.7% of the variance in PTSD symptoms. Five variables remained significant in the final model; greater peritraumatic distress (β= 0.240, P < .001), greater peritraumatic dissociation (β= 0.174, P < .001), greater problem‐solving coping (β= 0.103, P < .01), greater routine work environment stress (β= 0.182, P < .001), and lower levels of social support (β=−0.246, P < .001). These results were largely consistent with the proposed conceptual model. Next steps in this line of research will be to test this model prospectively in a sample of 400 police academy recruits assessed during training and currently being followed for the first 2 years of police service.

Why are hispanics at greater risk for PTSD

Several studies have found that Hispanic Americans have higher rates of posttraumatic stress disorder (PTSD) than non-Hispanic Caucasian and Black Americans. The authors 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. The authors 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 PTSD symptoms among Hispanics. Results are discussed in the context of Hispanic culture and may be important for prevention of mental illness in the fastest growing ethnic group in the United States.

Strengths of character and posttraumatic growth

How are strengths of character related to growth following trauma? A retrospective Web-based study of 1,739 adults found small, but positive associations among the number of potentially traumatic events experienced and a number of cognitive and interpersonal character strengths. It was concluded that growth following trauma may entail the strengthening of character.

PTSD symptoms predict waking salivary cortisol levels in police officers

This study examines whether pre- or post-dexamethasone salivary cortisol is related to cumulative critical incident exposure, peritraumatic responses, or post-traumatic stress disorder (PTSD) symptom severity. Thirty active duty police officers completed the study protocol, which included measures of peritraumatic emotional distress, peritraumatic dissociation, duty-related trauma exposure, and PTSD symptoms. Salivary cortisol was consolidated into three outcome variables: (1) pre-dexamethasone free cortisol levels at 1, 30, 45, and 60 min after awakening, (2) post-dexamethasone cortisol levels at the identical wake times, and (3) percentage of cortisol suppression. Control variables included age, gender, average daily alcohol use, night shift work, routine work environment stressors, and salivary dexamethasone levels. Zero order correlations showed that greater levels of PTSD symptoms, peritraumatic distress, and peritraumatic dissociation were associated with lower levels of pre-dexamethasone cortisol levels on awakening, but were not associated with the other two cortisol variables. A trend was also noted for older subjects to have lower pre-dexamethasone cortisol on awakening. When these four predictors were entered simultaneously in a regression analysis, only age and PTSD symptom severity significantly predicted pre-dexamethasone awakening cortisol levels. These results replicate previous research indicating a relationship between greater PTSD symptoms and lower levels of basal cortisol on awakening, and extend this finding to a previously unstudied non-treatment seeking population, urban police.

Effects of gender and ethnicity on duty-related posttraumatic stress symptoms among urban police officers.

We studied 655 urban police officers (21% female, 48% white, 24% black, and 28% Hispanic) to assess ethnic and gender differences in duty-related symptoms of posttraumatic stress disorder (PTSD). We obtained self-report measures of: a) PTSD symptoms, b) peritraumatic dissociation, c) exposure to duty-related critical incidents, d) general psychiatric symptoms, e) response bias due to social desirability, and f) demographic variables. 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. Contrary to expectation, we found no gender differences in PTSD symptoms. 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 well-established finding of greater PTSD symptoms among civilian women.

Prospective Prediction of Posttraumatic Stress Disorder Symptoms Using Fear Potentiated Auditory Startle Responses

BACKGROUND Posttraumatic stress disorder (PTSD) has been most consistently associated with exaggerated physiologic reactivity to startling sounds when such sounds occur in threatening contexts. There is conflicting evidence about whether startle hyperreactivity is a preexisting vulnerability factor for PTSD or an acquired result of posttrauma neural sensitization. Until now, there have been no prospective studies of physiologic reactivity to startling sounds in threatening contexts as predictors of PTSD symptoms. METHODS One hundred and thirty-eight police academy cadets without current psychopathology were exposed to repeated 106-dB startling sounds under increasing (low, medium, or high) threat of mild electric shock while their eye-blink electromyogram, skin conductance, heart rate, and subjective fear responses were recorded. Measures of response habituation were also calculated. Following 1 year of exposure to police-related trauma, these participants were assessed for PTSD symptom severity. RESULTS After accounting for other baseline variables that were predictive of PTSD symptom severity (age and general psychiatric distress), more severe PTSD symptoms were prospectively and independently predicted by the following startle measures: greater subjective fear under low threat, greater skin conductance under high threat, and slower skin conductance habituation. CONCLUSIONS These results imply that hypersensitivity to contextual threat (indexed by greater fear under low threat), elevated sympathetic nervous system reactivity to explicit threat (indexed by larger responses under high threat), and failure to adapt to repeated aversive stimuli (evidenced by slower habituation) are all unique preexisting vulnerability factors for greater PTSD symptom severity following traumatic stress exposure. These measures may eventually prove useful for preventing PTSD.

Association between childhood trauma and catecholamine response to psychological stress in police academy recruits

BACKGROUND Childhood trauma is a risk factor for anxiety disorders in adulthood. One possible mechanism for this association is an increased neuroendocrine response to stress in adults with a history of childhood trauma. METHODS In a cross-sectional study, 76 police academy recruits (mean [+/-SD] age 28 +/- 5 years, 10 female) were exposed to a video depicting real-life officers exposed to highly stressful incidents. Salivary cortisol and 3-methoxy-4-hydroxy-phenylglycol (MHPG, the major metabolite of norepinephrine) were collected at baseline, immediately after the video, and 20 min after the video. Childhood trauma before age 14 was assessed with an interview (Life Stressor Checklist-Revised). RESULTS Exposure to the video elicited significant MHPG and cortisol responses in both groups. Recruits with childhood trauma histories (n = 16) had a significantly greater MHPG response, as evidenced by a group effect (F = 8.0, p < .01), and a group x time interaction (F = 4.1, p < .05). The cortisol response did not differ between groups. CONCLUSIONS Police academy recruits with childhood trauma histories have an increased catecholamine response to psychological stress. This might serve as a risk factor for anxiety disorders in recruits, and these findings might generalize to other groups with a history of childhood trauma.

Gender and PTSD: What Can We Learn From Female Police Officers?

Studies of civilians typically find that female gender is a risk factor for posttraumatic stress disorder (PTSD). Police and military studies often find no gender differences in PTSD. We compared 157 female police officers and 124 female civilians on several variables including trauma exposure, peritraumatic emotional distress, current somatization, and cumulative PTSD symptoms. We found that despite greater exposure to assaultive violence in the officer group, female civilians reported significantly more severe PTSD symptoms. Elevated PTSD symptoms in female civilians were explained by significantly more intense peritraumatic emotional distress among female civilians. We also found that female officers showed a stronger direct relationship between peritraumatic emotional distress and current somatization. Our findings suggest that apparent gender differences in PTSD may result from differences in peritraumatic emotionality, which influence subsequent PTSD and somatization symptoms. Emotionality may be more important than biological sex in understanding gender differences in PTSD.

Fear-Potentiated Startle and Posttraumatic Stress Symptoms in Urban Police Officers

We studied the effects of increasing threat conditions on self-reported emotion, eyeblink electromyogram, and skin conductance responses to startling sounds in 55 police officers who endorsed a range of PTSD (posttraumatic stress disorder) symptoms. We found that contextual threat affected both physiologic and self-reported emotional responses. Greater PTSD symptom severity was related to greater physiologic responses under the low and medium but not under the high threat condition. The relationship between PTSD symptoms and physiologic responses was neither explained by self-reported emotional responses nor preexisting reported exaggerated startle symptoms. Our results emphasize the importance of contextual threat and suggest that laboratory measures of startle improve upon self-reported exaggerated startle alone in indexing PTSD symptom severity in urban police officers.