Originally published in American Journal of Psychiatry, 1997, 154(11), 1576-1581. Posted at www.trauma-pages.com with the authors' permission. Note that this online version may have minor differences from the published version.
Address reprint requests to Dr. Brian Engdahl, Psychology Service (116B), VA Medical Center, One Veterans Drive, Minneapolis, MN 55417.
From the U.S. Dept. of Veterans Affairs Medical Center1, Minneapolis and Department of Psychology2, the Institute of Child Development3, and Department of Psychiatry4, University of Minnesota.
Supported by research funds from the Department of Veterans Affairs, and the DVA Medical Center, Minneapolis. The authors thank the POW volunteers, Julee Blake, Daniel Sandstrom, and Nicholas Michel for their assistance in this project.
Portions of the data in this article were presented at the International Society for Traumatic Stress Studies Convention, Boston, MA; November 2-6, 1995.
Objective: The goal of this study was to assess and describe the long-term impact of traumatic prisoner of war (POW) experiences within the context of posttraumatic psychopathology. Specifically, the authors attempted to investigate the relative degree of normative response represented by posttraumatic stress disorder (PTSD) in comparison to other DSM Axis I disorders often found to be present or comorbid in survivors of trauma.
Method: A community sample of 262 American World War II and Korean War former POWs was recruited. These men had been exposed to the multiple traumas of combat, capture, and imprisonment, yet few had ever sought mental health treatment. They were assessed for psychopathology using diagnostic interviews and psychodiagnostic testing. Regression analyses were used to assess the contributions of age at capture, war trauma, and postwar social support to PTSD and the other diagnosed disorders.
Results: More than half of the sample (54%) met criteria for lifetime PTSD, and 30% met criteria for current PTSD. The most severely traumatized group (POWs held by the Japanese) had lifetime rates of 84% and current rates of 58% for PTSD. Fifty-five percent of those with current PTSD were free from the other current Axis I disorders (uncomplicated PTSD). Also, 34% of those with lifetime PTSD had PTSD as their only lifetime Axis I diagnosis. Regression analyses indicated that age at capture, severity of trauma exposure, and postmilitary social support were moderately predictive of PTSD and only weakly predictive of other disorders.
Conclusions: These findings indicate that PTSD is a persistent, normative, and primary consequence of exposure to severe trauma.
Many studies indicate that a majority of individuals exposed to severe trauma develop posttraumatic stress disorder (PTSD) (e.g., former prisoners of war (POWs; 1-3), torture victims (4), and survivors of war in the former Yugoslavia (5)). In a sample of American POWs a lifetime PTSD rate of 67% was found (1). Among school children exposed to a sniper attack, 58% met criteria for PTSD (6). The National Vietnam Veterans Readjustment Study (NVVRS; 7) found high lifetime PTSD rates among veterans of heavy combat (30%) and among combat-wounded veterans (67%). PTSD rates of 59% to 66% were reported among crime victims exposed to life threat combined with injury (8). The National Comorbidity study (NCS; 9) found lifetime PTSD rates among those exposed to severe trauma ranging from 39% for combat to 65% for rape. Studies in which trauma exposure has been less severe, however, suggest that most subjects exposed to trauma did not develop PTSD (10-12). It further has been proposed that PTSD may represent an abnormal, rather than a normal, response to trauma (13, 14).
Trauma exposure alone does not always lead to PTSD, nor does trauma severity fully predict the likelihood of developing PTSD. Other contributing factors have been identified, including prior trauma exposure (15), a history of childhood conduct problems (7), pre-trauma personality (16), heritability (17), age at trauma exposure (18, 19), and post-traumatic factors such as social support (20) and exposure to re-activating stressors (21). Green, et al. (22) examined the contribution of premilitary, military, and postmilitary risk factors to PTSD and other postwar diagnoses in a sample of Vietnam veterans. Although pre- and postmilitary factors were contributory, PTSD was primarily related to war trauma. Panic disorder was also highly related to war trauma. Prewar functioning played a stronger role in several non-PTSD diagnoses.
Although risk factors other than trauma may affect posttraumatic psychiatric status when trauma is less severe or single-exposure, these other risk factors may decrease in significance as the severity and duration of trauma exposure increase (23). Foy (24) found that, while Vietnam veterans with PTSD generally had the highest rates of family psychopathology, the contribution of family history was nonsignificant for those with high combat exposure; regardless of family history of mental illness, veterans with high combat exposure developed high rates of PTSD. In a sample of POWs, family history of mental illness, premilitary adjustment problems, and severe childhood trauma were not predictive of PTSD development (18).
In addition to lack of control for trauma severity, variance in assessment methods has affected the results of studies assessing PTSD. The Diagnostic Interview Schedule (DIS; 25), based on DSM-III criteria, was often used despite the low sensitivity of early versions to the presence of PTSD (26), particularly when administered by nonclinicians (7). For example, the DIS was used in community prevalence studies and yielded lifetime rates of 1.0% (10) and 1.3% (27). Three recent studies using DSM-III-R criteria reported significantly higher rates of PTSD. Structured interviews using a DSM-III-R version of the DIS found histories of PTSD in 12.3% of a sample of U.S. women (28), and among 11.3% of women and 6% of men enrolled in an urban health maintenance organization (11). And although NCS procedures reportedly underdiagnose PTSD (9), using the Composite International Diagnostic Interview (29), the NCS yielded a general population lifetime prevalence estimate of 7.8% for PTSD.
Other disorders, most commonly other anxiety disorders, depression, and alcohol abuse, are elevated among those exposed to trauma (9, 30, 31). This comorbidity pattern resembles that found with other anxiety syndromes (32). Studies assessing both current and lifetime diagnoses, however, suggest that with time, co-occurring disorders fade while PTSD persists (7, 33, 34). In the NVVRS (7), the comorbidity of PTSD with a group of other common DIS-detected psychiatric disorders declined from approximately 99% lifetime to approximately 50% at the time of interview.
Particularly in community surveys of those with severe trauma exposure, PTSD has been shown to be central, common, and persistent, consistent with a view of PTSD as a normative response. With this in mind, we present data describing psychiatric disorders and their correlates in a community sample of persons with histories of severe trauma exposure.
Sixty-three percent of our sample sustained wounds or injuries in the course of their combat and captivity. Duration of individual combat involvement ranged from 1 to 31 months (mean=4.1, SD=3.7). They had a mean Combat Exposure Scale score of 21.5 (SD=7.2), placing the group in the moderate range of combat exposure (41). Their length of captivity ranged from 1 to 46 months (mean=16.1, SD=14.2). They experienced an average weight loss during captivity of 27.7% (SD=14.2).
DSM-IV redefined PTSD Criterion A (the stressor criterion) to require that intense fear, helplessness, or horror be experienced during trauma exposure. Reexamination of individuals' DSM-III-R Criterion A information indicated that all of our subjects met DSM-IV Criterion A requirements. In addition, DSM-IV adds a Criterion F, requiring that the PTSD symptoms cause clinically significant distress or impairment. One subject positive for current DSM-III-R PTSD did not appear distressed or impaired by his symptoms. His GAF score was 85. The remaining current PTSD cases had a mean GAF score of 65.7 (SD=9.1), which, while suggesting impairment in functioning, may be interpreted as in the moderate range. It is important to note, however, that in PTSD in general, and subjects in this sample in particular, severity of impairment may not be accurately reflected in functional ratings. These veterans have survived and demonstrated an ability to function under the most extreme circumstances. Furthermore, many have reported that an important facet of survival involved hiding their emotions and reactions. Finally, internalizing symptoms such as intrusive recollections, social isolation, avoidance of remindful stimuli, and 50 years of disturbed sleep patterns, may not be adequately indexed in GAF criteria.
DSM-IV also moves one symptom, physiological reactivity on exposure to cues, from Criterion group D (increased arousal) to group B (reexperiencing the trauma). Re-scored SCID data reclassified six subjects from DSM-III-R positive to DSM-IV negative for lifetime PTSD, and three subjects from DSM-III-R positive to DSM-IV negative for current PTSD. DSM-III-R results are reported below.
The mean number of lifetime Axis I disorders per person was 2.3 (SD=1.3, range=0 to 7). PTSD was the most prevalent disorder: 53% (N=140) met lifetime criteria and 29% (N=77) met current criteria (Table 1), comparable to the NVVRS findings noted above (7). The lifetime rate of 37% for alcohol abuse or dependence is somewhat higher than rates noted in the ECS (42) among older males in the general population. As a group, POWs held by Germany had a lower degree of trauma exposure than those held by Japan or in Korea, with corresponding differences in rates of certain disorders. Two multivariate analyses of variance examined the interaction of diagnoses with theater of capture: for lifetime diagnoses, PTSD (F=16.0, df= 2, 260, p<.0001), panic disorder (F=5.1, df= 2, 260, p<.01), and social phobia (F=7.2, df= 2, 260, p<.001) varied significantly by theater of capture. For current diagnoses, PTSD (F=19.9, df=2, 260, p<.0001) and panic disorder (F=5.0, df=2, 260, p<.01) varied significantly by theater of capture. Higher rates of these disorders for POWs held by Japan or in Korea are observed in Table 1.
|DSM-III-R Diagnosis:||Japan (N=56)||Korea (N=15)||Europe (N=191)||Total (N=262)|
|Posttraumatic stress disorder||84||59||67||47||44||19||53||29|
|Generalized anxiety a||-||16||-||13||-||7||-||9|
aThe SCID does not assess lifetime generalized anxiety disorder or lifetime dysthymia.
All figures shown are percentages.
Only 9.5% of our total sample were free of all current PTSD symptoms. Eighty-two percent of subjects without current PTSD also were free from the other 33 current Axis I disorders assessed by the SCID. Fifty-five percent of those with current PTSD were free from the other current Axis I disorders; they had uncomplicated PTSD. Also, 34% of those with lifetime PTSD had PTSD as their only lifetime Axis I diagnosis.
Table 2 summarizes multiple regression equations that used age at time of capture, indicators of trauma exposure, and the social support index to predict current PTSD and the other most frequent current Axis I disorders. Preliminary analyses showed that many theoretically relevant variables were not significantly correlated with Axis I diagnoses and were statistically infrequent. For example, fewer than 2% admitted to having been treated for a mental problem or to a family history of mental problems. Statistical transformations of these skewed variables did not yield significant correlations with Axis I diagnoses, therefore they were not included in Table 2 analyses.
|Predictor variable||PTSD||Generalized Anxiety||Panic Disorder||Social Phobia||Major Depression||Dysthymia||Alcohola|
|Age at capture||-.13 b||-.15 c||-.14 c||-||-||-||-|
|Combat Exposure Scale score (39)||.21b||-||-||-||-||-||-|
|Weight loss during captivity||.30 b||-||-||-||-||-||-|
|Experienced torture/beatings||.21 b||.15 b||-||.18 c||-||-||-|
|Social support||.14 b||-||-||-||-||-||-|
|Multiple R 2||.33||.07||.05||.05||.03||.03||.01|
a Alcohol abuse or alcohol dependence.
b Regression coefficient significance: p<.01 (two-tailed).
c Regression coefficient significance: p<.05 (two-tailed).
The five variables shown in Table 2 were the only significant predictors of Axis I diagnostic status and together they accounted for 33% of the variance in PTSD status. Age at capture was negatively related to PTSD: being older during the period of trauma exposure was a protective factor against later PTSD. Table 2 also shows the much lower power of these variables to predict other Axis I disorders. Only two of the variables were significant predictors of other disorders: age at capture (generalized anxiety and panic disorder) and the experience of torture or beatings (generalized anxiety and social phobia). None of the prediction equations accounted for more than 7% of the variance in the other disorders. Parallel analyses (not shown) for the lifetime diagnoses yielded highly similar results, with the predictors accounting for 33% of the variance in lifetime PTSD status and no more than 7% of the variance in any of the other lifetime Axis I disorders. Separate discriminant analyses (not shown) based on the predictor variables in Table 2 yielded highly significant functions that correctly classified 77% of the lifetime PTSD cases and 80% of the current PTSD cases, using a jackknifed classification procedure. Parallel discriminant analyses attempting to predict the comorbid disorders were non-significant.
If trauma response were nonspecific, a greater scattering of significant regression weights would be observed across Table 2, as would a more robust ability to predict status on disorders other than PTSD. Table 2 shows, however, a concentration of predictive power under the disorder of PTSD, suggesting that trauma response is better represented by PTSD than by the other disorders.
In accord with many previous reports, the present findings indicate that PTSD is both a frequent and central consequence of exposure to severe trauma and the diagnostic construct that best represents primary responses to trauma exposure. Consistent with other findings, lifetime PTSD was found in over half (53%) of our subjects, with a substantial minority (29%) still meeting PTSD criteria 40-50 years after trauma exposure. In other words, only 45% of those with lifetime PTSD experienced sufficient symptom reduction to fall below criteria for current PTSD. The present findings also suggest that PTSD without comorbid Axis I diagnoses may be more common in certain trauma-exposed groups than previous studies might suggest.
Community surveys of individuals exposed to severe trauma (6-9) can lead to quite different conclusions than those suggested by studies of clinical samples. In the present study, few subjects had ever received mental health services and all subjects were both combat-exposed and subjected to the hardships of capture and captivity. This trauma exposure was comparable on common dimensions and average levels of trauma exposure were high. To illustrate, we present histories of two veterans who had not sought mental health treatment, and who met criteria for current and lifetime PTSD and no other Axis I disorders:
Upon repatriation, he met his 2 1/2 year old son for the first time. He and his wife raised four children. Because his return to work at a brewery was unsatisfactory, he attended college for two years. He attempted to sell real estate for about a year, eventually returning to his original employer. He reported that, before the war, he was "interested in everything," however, upon return was interested in very little. He now is "very choosy about activities and interests" and his social contact is limited to his family. He has had peptic ulcer disease and chronic arthralgias of his knees since WWII. His chief psychiatric complaints include intrusive recollections (diminishing in intensity somewhat over the years), difficulties falling asleep and staying asleep since the war (averaging only 4 hours per night), and feeling distant from and mistrustful of people outside his family. He has no close friendships and does not associate with other veterans. Any portrayal of disasters or injuries (particularly coverage of the Gulf War and its bombings) provokes nightmares of his POW experiences. He never sought help for these problems, and was uninterested in any new mental health evaluations or treatment. His only Axis I disorder was PTSD, lifetime and current.
His only Axis I disorder was PTSD, lifetime and current. He recalled complaining of nervousness to several nonpsychiatric physicians after WWII but was not referred for mental health services; he reported being told he would "have to live with it". His records indicate he refused tranquilizers. Since participation in the present study, he joined a POW support group that meets twice monthly. He appears anxious and speaks rapidly. He suffers a trauma-related phobia of closed spaces and from most of the PTSD symptoms, chiefly daily intrusive recollections, frequent nightmares, hypervigilance, and survivor guilt. His only friends are a few other POWs of Japan.
Cases such as these appear in community samples and offer insights into chronic untreated psychiatric disorders such as PTSD. Generalizations about the effects of trauma are potentially misleading when drawn from studies of clinical populations that offer insights more specific to treatment-seeking samples. In such samples individuals with Axis I disorders comorbid with PTSD may be overrepresented and vulnerability to trauma's effects may be elevated. See King and King (45) for a discussion of other validity issues in PTSD research.
Being older at the time of trauma exposure appeared to reduce the risk for later PTSD symptoms, however understanding of other protective factors is currently minimal. Research has emphasized vulnerability factors in the search for PTSD's causal bases. More emphasis on protective factors is needed (e.g., 46). Shifting more attention to those who experience few negative effects of trauma exposure might also improve our understanding of recovery mechanisms and contribute to more effective treatment (47).
Our findings that 53% of all the POWs, including 84% of those held by Japan, met full criteria for lifetime PTSD are consistent with earlier reports (1, 2) and indicate the unremitting nature of trauma-related psychopathology in significant proportions of persons exposed to severe trauma. In this, as in a substantial number of other studies including many cited above, trauma exposure was the strongest risk factor for the development of PTSD. Severity of trauma exposure is clearly predictive of PTSD and less predictive of the other disorders commonly observed in trauma survivors. It has been suggested that the longer PTSD lasts, the less important the role of traumatic exposure becomes in explaining posttraumatic symptoms (48). Our data suggest otherwise: 45-50 years later, trauma exposure remains the strongest predictor of PTSD symptoms. Our findings indicate that in the context of severe trauma, PTSD is a persistent, normative, and primary response.
1.Kluznik JC, Speed N, Van Valkenburg C, McGraw R: Forty-year follow-up of United States prisoners of war. Am J Psychiatry 1986; 143:1443-1446.
2.Goldstein G, van Kammen W, Shelly C, Miller DJ, van Kammen DP: Survivors of imprisonment in the Pacific theater during World War II. Am J Psychiatry 1987; 144:1210-1213.
3.Eberly RE, Engdahl BE: Prevalence of somatic and psychiatric disorders among former prisoners of war. Hosp Comm Psychiatry 1991; 42:807-813.
4.Ramsay R, Gorst-Unsworth C, Turner S: Psychiatric morbidity in survivors of organised state violence including torture: a retrospective series. Brit J Psychiatry 1993; 162:55-59.
5.Weine SM, Becker DF, McGlashan TH, Laub D, Lazrove S, Vojvoda D, Hyman L: Psychiatric consequences of "ethnic cleansing": clinical assessments and trauma testimonies of newly resettled Bosnian refugees. Am J Psychiatry 1995; 152:536-542.
6.Pynoos RS, Frederick C, Nader K, Arroyo W, Steinberg A, Eth S, Nunez F, Fairbanks L: Life-threat and posttraumatic stress in school-age children. Arch Gen Psychiatry 1987; 45:1057-1063.
7.Kulka RA, Schlenger WE, Fairbank JA, Hough RL, Jordan BK, Marmar CR, Weiss DS: National Vietnam Veterans Readjustment Study: tables of findings and technical appendices. New York, Brunner/Mazel, 1990.
8.Kilpatrick DG, Resnick HS: Posttraumatic stress disorder associated with exposure to criminal victimization in clinical and community populations, in Posttraumatic Stress Disorder: DSM-IV and Beyond. Edited by Davidson [J]RT, Foa EB. Washington DC, American Psychiatric Press, 1993, pp 113-146.
9.Kessler RC, Sonnega A, Bromet E, Hughes M, Nelson CB: Posttraumatic stress disorder in the National Comorbidity Survey. Arch Gen Psychiatry 1995; 52:1048-1060.
10.Helzer JE, Robins LN, McEvoy L: Post-traumatic stress disorder in the general population. New England J Med 1987; 317:1630-1634.
11.Breslau N, Davis GC, Andreski P, Peterson E: Traumatic events and posttraumatic stress disorder in an urban population of young adults. Arch Gen Psychiatry 1991; 48:216-222.
12.Southwick SM, Morgan A, Nagy LM, Bremner D, Nicholaou AL, Johnson DR, Rosenheck R, Charney DS: Trauma-related symptoms in veterans of Operation Desert Storm: a preliminary report. Am J Psychiatry 1993; 150:1524-1538.
13.Worthington ER: Demographic and pre-service variables as predictors of post-military service adjustment, in Stress Disorders among Vietnam Veterans: Theory, Research and Treatment. Edited by Figley CR. New York, Brunner/Mazel, 1978, pp 173-187.
14.Yehuda R, McFarlane AC: Conflict between current knowledge about posttraumatic stress disorder and its original conceptual basis. Am J Psychiatry 1995; 152:1705-1713.
15.Bremner JD, Southwick SM, Johnson DR, Yehuda R, Charney DS: Childhood physical abuse and combat-related posttraumatic stress disorder. Am J Psychiatry 1993; 150:235-239.
16.Schnurr PP, Friedman MJ, Rosenberg SD: Premilitary MMPI scores as predictors of combat-related PTSD symptoms. Am J Psychiatry 1993; 150:479-483.
17.True WR, Rice J, Eisen SA, Heath AC, Goldberg J, Lyons MJ, Nowak J: A twin study of genetic and environmental contributions to liability for posttraumatic stress symptoms. Arch Gen Psychiatry 1993; 50:257-264.
18.Speed N, Engdahl BE, Schwartz J, Eberly RE: Posttraumatic stress disorder as a consequence of the prisoner of war experience. J Nerv Ment Dis 1989; 177:147-153.
19.King DW, King LA, Foy DW, Gudanowski DM: Prewar factors in combat-related posttraumatic stress disorder: structural equation modeling with a national sample of female and male Vietnam veterans. J Consult Clin Psychol 1996; 64:520-531.
20.Keane TM, Scott WO, Chavoya GA, Lamparski DM, Fairbank JA: Social support in Vietnam veterans with posttraumatic stress disorder: a comparative analysis. J Consult Clin Psychol 1985; 53:95-102.
21.Solomon, Z: Combat Stress Reaction: the enduring toll of war. New York, Plenum Press, 1993.
22.Green BL, Grace MC, Lindy JD, Gleser GC, Leonard A: Risk factors for PTSD and other disorders in a general sample of Vietnam veterans. Am J Psychiatry 1990; 147:729-733.
23.March JS: The nosology of posttraumatic stress disorder. J Anx Dis 1990;4:61-82.
24.Foy DW, Resnick HS, Sipprelle RC, Carroll EM: Premilitary, military, and postmilitary factors in the development of combat-related posttraumatic stress disorder. Beh Therapist 1987; 10:3-9.
25.Robins LN, Helzer JE, Croughan JL, Williams JBW, Spitzer RL: NIMH Diagnostic Interview Schedule, Version III. Rockville, MD: NIMH, Public Health Service, publication ADM-T-42-3 (5-8-81), 1981.
26.McFarlane AC, Papay P: Multiple diagnoses in posttraumatic stress disorder in the victims of natural disaster. J Nerv Ment Dis 1992; 180:498-504.
27.Davidson RT, Hughes D, Blazer D, George LK: Posttraumatic stress disorder in the community: an epidemiological study. Psychol Med 1991; 21:1-19.
28.Resnick HS, Kilpatrick DG, Dansky BS, Saunders BE, Best CL: Prevalence of civilian trauma and posttraumatic stress disorder in a representative national sample of women. J Consult Clin Psychol 1993 ;61:984-991.
29.World Health Organization: Composite International Diagnostic Interview. Geneva, Switzerland, World Health Organization, 1990.
30.Brett, EA: Classification of PTSD in DSM IV: Anxiety disorder, dissociative disorder, or stress disorder, in Posttraumatic Stress Disorder: DSM-IV and Beyond. Edited by Davidson RT, Foa EB. Washington DC, American Psychiatric Press, 1993, pp 191-204.
31.Rundell JR, Ursano RJ, Holloway HC, Silberman EK: Psychiatric responses to trauma. Hosp Comm Psychiatry 1989; 40:68-74.
32.de Ruiter C, Rijkekn H, Garssen B, van Schaik A, Kraaimaat F: Comorbidity among the anxiety disorders. J Anxiety Disorders 1989; 3:57-68.
33.Blank, Jr. AS: The longitudinal course of posttraumatic stress disorder, in Posttraumatic Stress Disorder: DSM-IV and Beyond. Edited by Davidson RT, Foa EB. Washington DC, American Psychiatric Press, 1993, pp 3-22.
34.Page WF, Engdahl BE, Eberly RE: The persistence of PTSD in former POWs, in PTSD: Acute and Long-Term Responses to Trauma. Edited by Fullerton C, Ursano R. Washington, DC, American Psychiatric Press, in press.
35.Spitzer RL, Williams JB: Structured Clinical Interview for DSM-III-R-Non-patient Version (Modified for Vietnam veterans readjustment study 4/1/87). New York, New York State Psychiatric Institute, Biometrics Research, 1986.
36.Spitzer RL, Williams JB, Gibbon M, First MB: Structured Clinical Interview for DSM-III-R. Washington DC, American Psychiatric Press, 1990.
37.Engdahl BE, Eberly RE, Blake JD: The assessment of posttraumatic stress disorder in World War II veterans. Psychol Asses 1996; 8:445-449.
38.Keane TM, Fairbank JA, Caddell JM, Zimmerling RT, Taylor KL, Moira CA: Clinical evaluation of a measure to assess combat exposure. Psychol Assess 1989; 1:53-55.
39.Laufer RS, Yaeger T, Frey-Wouters E, Donellan J. Post-war trauma: Social and psychological problems of Vietnam veterans and their peers; in Legacies of Vietnam, vol III. 1981; Washington, DC: U.S. Government Printing Office.
40.Veterans Administration: Former POW Medical History (VA Form 10-0048) 1984; Washington, DC: U.S. Government Printing Office.
41.Spiro A, Schnurr PP, Aldwin CA: Prevalence of combat-related PTSD in older men. Psychol and Aging 1994; 9:17-26.
42.Kessler RC, McGonagle KA, Zhao S, Nelson CB, Hughes M, Eshelman S, Wittchen H-U, Kendler KS: Lifetime and 12 month prevalence of DSM-III-R psychiatric disorders in the United States: results from the National Comorbidity Survey. Arch Gen Psychiatry 1994; 51:8-19.
43.Dawes G: Prisoners of the Japanese. New York: Morrow, 1993.
44.Jones BB: The December ship: a story of Lt. Col Arden R. Boellner's capture in the Phillipines, imprisonment, and death in a World War II Japanese Hellship. Jefferson, NC: McFarland & Co, 1992.
45.King DW, King LA: Validity issues in research on Vietnam veteran adjustment. Psychol Bull 1991; 109:107-124.
46.Hendin H, Haas AP: Combat adaptations of Vietnam veterans without posttraumatic stress disorders. Am J Psychiatry 1984; 141:956-959.
47.Basic Behavioral Science Task Force of the National Advisory Mental Health Council: Basic Behavioral Science Research for Mental Health: Vulnerability and Resilience. Am Psychologist 1996;51:22-28.
48.McFarlane AC, Yehuda R: Resilience, vulnerability, and the course of posttraumatic reactions, in Traumatic Stress: the Effects of Overwhelming Experience on Mind, Body, and Society. Edited by van der Kolk BA, McFarlane AC, Weisaeth L. New York, Guilford Press, 1996, pp 155-181.