Psychological Reports, 1990, 67, 595-605. 63 Psychological Reports 1990
COMPARISON OF CHARACTERISTICS O F VIETNAM VETERANS WITH AND WITHOUT POSTTRAUMATIC STRESS DISORDER ' LAURAINE CASELLA AND ROBERT W. MOTTA
HoJstra University 3ztrnrnary.-Characteristics of 107 Vietnam veterans with and without Posttraumatic Stress Disorder (PTSD), who had been exposed to varying levels of combat, were compared. Severity of psychopathology as assessed on the Eysenck Personality Questionnaire, locus of control orientation as measured by the Nowicki-Strickland Internal-External Control Scale, and ability to have provided structure and meaning to the Vietnam experience were examined. Compared to veterans with Posttraumatic Stress Disorder, those without the disorder had lower Neuroticism and Psychoticism scores, were more internal in their locus of control orientation, and were more likely to have shown ability to provide structure to the Vietnam experience. The additional finding that veterans with high combat experience but without PTSD evidenced less neuroticism than low combat veterans without PTSD provides evidence that those who did not develop the disorder despite high exposure to combat stress are individuals with exceptional emotional strength and resilience.
Most research on the postwar adjustment of Vietnam veterans has focused on variables associated with the development of Posttraumatic Stress Disorder (PTSD) and other evidence of maladjustment. Numerous researchers have studied prernilitary, d t a r y , and postmditary adjustment factors associated with its development (Goodwin, Davis, & Robins, 1975; Nace, O'Brien, Mintz, Ream, & Meyers, 1978; Worthington, 1978). Many others, particularly more recent investigators, have emphasized the importance of extent of combat exposure in the acquisition of PTSD (DeFazio, Rustin, & Diamond, 1975; Foy & Card, 1987; Foy, Sipprelle, Ruegar, & Carroll, 1984; Pearce, Schauer, Garfield, Ohlde, & Patterson, 1985; Solkoff, Gray, & Keill, 1986). Few studies have focused more specifically upon veterans without PTSD and the identification of those factors which appear to have protected these individuals from experiencing long-term negative effects subsequent to their combat experiences. As part of a comprehensive investigation of Vietnam veterans, Egendorf, Remez, and Farley (1981) conducted a case-by-case study of the 5 to 10% of a sample of 169 Vietnam veterans who were determined to have attamed the highest level of occupational, interpersonal, and social adjustment. These researchers concluded that the well-adjusted Viet-
'Address correspondence to R. W. Motta, Ph.D., Department of Psychology, Monroe Hall, Hofstra University, Hempstead, NY 11550.
596
L. CASELLA
&
R. W. MOTTA
nam veterans in their sample were skilled problem solvers and tended to view difficult circumstances as a series of challenges. Also, they valued self-discipline and reported having felt some sense of responsibility for the conflict once in Vietnam. I n addition, Egendorf, et a/. (1981) maintained that these veterans were critical of the war and reported sensitivity to the Vietnamese that is atypical among Vietnam veterans over-all. Hendin and Haas (1984) offered the view that postwar adjustment should not be viewed only as a reflection of preexisting character strengths or weaknesses since some veterans who have evidenced postwar adjustment difficulties appear to have had healthy personality structures prior to having served in Vietnam. I n addition, they pointed out that some well-adjusted veterans have prewar histories of unstable family lives and have had little support upon their return from Vietnam. I n an introductory analysis, these investigators compared the combat adaptations of a group of 10 Vietnam veterans who had not developed the disorder with those of approximately 100 Vietnam veterans with the disorder. The factors that they cited as related to a positive postwar adjustment included having ability to function calmly under pressure, having an intellectual understanding of the objectives and strategies of missions, having the capability to cope with the war in terms of the limited objectives of each day's mission, and the ability to trust one's own judgment in making decisions about survival. The present research study compared on a number of relevant characteristics Vietnam veterans who have not developed Posttraumatic Stress Disorder with those who are suffering from the disorder. These include degree of psychological symptomatology, locus of control orientation, and ability to have provided a structure to the Vietnam experience. A primary focus was on Vietnam veterans without the disorder, particularly those exposed to high combat. I t was hypothesized that veterans exposed to more combat would score in the direction of more psychopathological symptomatology as measured on the Eysenck Personality Questionnaire than those in groups with less combat. I t was further hypothesized that in comparison to veterans who have not developed PTSD, those with the disorder would evidence more psychopathological symptomatology, score in the more external direction on the Nowicki-Strickland Control Scale, and be less likely to show ability to have provided their own structure to the often chaotic Vietnam experience as assessed by the Vietnam War Experience Questionnaire. Finally, it was hypothesized that in comparison to all other veteran groups, those who d o not suffer from PTSD despite high exposure to combat would evidence less psychopathological symptomatology, score in the more internal direction on locus of control, and be more likely to indicate ability to have provided a structure to the Vietnam war experience.
VIETNAM VETERANS WITH AND WITHOUT PTSD
Subjects The subjects were 107 male veterans of the Vietnam war who served between 1962 and 1973. They were recruited from a New York Veterans Administration Hospital and from four New York Vietnam Veterans centers. TABLE 1 CHARACTERISTICS OF SIX GROUPSIN VIETNAMVETERAN SAMPLE Characteristic
PTSD Absent High Moderate Low Combat Combat Combat
PTSD Present Low High Moderate Combat Combat Combat
Age n
M
SD Current Marital Status n % Single % Married % Separated/Divorced
Education n < High School, % High School Grad., % Some College or Trade, % College Grad., % Postgrad., % Employment Type, % n 1 2 3 4
5 6 7 8 Note.-1
= Professional and technical workers, 2 = Managers, officials, and proprietors, 3 = Clerical and sales, 4 = S u e d workers and Foremen, 5 = Semiskilled workers, 6 = Service workers, 7 = Laborers, unskilled workers, and 8 = Unemployed/retired.
The veterans' scores on the Mississippi Scale for Combat-related Posttraumatic Stress (Keane, Caddell, & Taylor, 1986) and The Combat Scale-Revised (Laufer, 1988) were used to place them into one of six groups. The groups were (1) veterans without PTSDIhigh combat exposure, (2) veterans without PTSD/moderate combat exposure, (3) veterans without PTSD/low combat exposure, (4) veterans with P T S D b g h combat exposure,
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L. CASELLA & R. W. MOTTA
(5) veterans with PTSDImoderate combat exposure, and (6) veterans with PTSD/low combat exposure. Procedure Testing was carried out individually and in groups, depending on the facility involved. Subjects were presented an assessment packet containing a demographic questionnaire and the remaining scales which they were instructed to return upon completion. Subjects were advised that the findings of the investigation would be made available to those who participated. Measures Mississippi Scale for Combat-related Posttraumatic Stress Disorder.-The Mississippi Scale for Combat-related PTSD (Keane, et al., 1986) is a 35-item scale derived from DSM-I11 criteria. Items are rated on a five-point Likert scale and summed to yield a total score which ranges from 35 to 175. A cut-off score of 107 was selected by the originators of the scale, since this cut-off gave accurate classification for 93% of Vietnam veterans with Posttraumatic Stress Disorder. Combat Scale-Revised.-The Combat Scale-Revised (Laufer, 1988) was used as a measure of combat exposure. I t consists of 15 hscrete events which are differentially weighted according to the severity of the experience. They yield an over-all score, ranging from 0 to 21, designed to quantify exposure to combat. Scores from 0 to 6 indicate low combat exposure, scores from 7 to 12 indlcate moderate combat exposure, and scores from 13 to 2 1 are indicative of high combat exposure. Eysenck Personality Questionnaire.-The Eysenck Personality Questionnaire (Eysenck & Eysenck, 1975) assesses various personality dimensions. The Neuroticism and Psychoticism subscales were used to measure psychopathological symptomatology. Nowicki-Strickland Internal-External Control Scale.-The Nowicki-Strickland Internal-External Control Scale for Adults (Nowicki & Duke, 1974) was designed as a measure of locus of control orientation or the extent to which an individual perceives that events are controlled by internal or external factors. Vietnam War Experience Questionnaire.-The Vietnam War Experience Questionnaire is a 10-item scale constructed for this study to assess the ability to have structured the Vietnam experience. The scale was validated by asking 10 individual raters to classify each item as either "structured" or "unstructured." "Structured" items were defined as those which indicated the abllity to have provided organization, conceptualization, or meaning to the experience. Examples of structured items are "The politics of the war were clear to me," h he way that I dealt with being in Vietnam was to concentrate on getting through one day at a time," and "My religious beliefs
599
VIETNAM VETERANS WITH AND WITHOUT PTSD
were what enabled me to get through each day." Examples of unstructured items are " W e I was stationed in Vietnam, I felt like I no longer knew who I was or what was important in my life" and "While in Vietnam I didn't know what was going on around me." There was 100% agreement on nine of the 10 items, with 80% agreement on the remaining item.
RESULTS The results are organized into sections representing data on each of the measures.
Eysenck Personality Questionnaire Veterans in the High Combat/No PTSD group (M = 8.39, SD = 4.81) had significantly lower Neuroticism scores than veterans in the High CombatlPTSD group (M = 18.71, SD = 3.61; t,,,,, = 8.29, p < .01), than veterans in the Moderate Combat/PTSD group (M = 19.67, SD = 2.52; t,,,, = 6.39, p< .01) and veterans in the Low Combat/No PTSD group (M = 11.78, SD = 5.99; t,, = 2.12, p< .05). TABLE 2 MEANSA N D STANDARD DEVIATIONS OF NEUROTICISM A N D PSYCHOTICISM SCORESO N EYSENCK PERSONNITY QLJESTIONNAIRE AS A FUNCTION OF ABSENCE OR PRESENCE OF PTSD AND LEVELOF C O ~ AEXPOSURE T Combat Group
n High M
23
8.39 4.81
2.61 2.15
23
18.71 3.61
7.67 3.54
31
9.19 5.24
2.90 1.80
3
19.67 2.52
8.67 1.53
23
11.78 6.00
3.13 2.56
3
17.00 4.36
10.00 4.58
SD Moderate M
Posttraumatic Stress Disorder Diagnosis Absent Diagnosis Present Neuroti- Psychotin Neuroti- Psychoticism cisrn cisrn cism
SD Law
M
SD Note.-Higher
scores indicate greater psychopathology
Analysis also indicated that veterans in the High CombatlNo PTSD group (M= 2.61, SD = 2.15) had significantly lower Psychoticism scores than veterans in the High CombatIPTSD group (M = 7.67, SD = 3.54; t,,,,, = 5.96, p< .OI) and veterans in the Moderate Combat/PTSD group (M = 8.67,
S D = 1.53; t,,,=6.12, p c . 0 1 ) . There were significant differences between combat groups based on their mean Neuroticism scores (F,,,,,= 3.16, p < .05). A post hoc comparison of means, using the Scheffi test, showed the High Combat group
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L. CASELLA & R. W. MOTTA
(M = 13.66, SD = 6.69) scored significantly higher than the Moderate Combat group (M = 10.12, SD = 5.87) and higher but not significantly differently from the Low Combat group (M = 12.38, SD = 6.0) on Neuroticism. In addition, the Scheffi test showed no significant difference between the mean Neuroticism scores of the Moderate Combat group and the Low Combat group. There were no significant differences among the mean Psychoticism scores of the High Combat (M = 5.19, SD = 3.87), Moderate Combat (M = 3.41, SD = 2.4 1) and Low Combat (M = 3.92, SD = 3.53) groups (F,,,,, = 2.96, p< .06). Nowicki-Strickland Control Scale Vietnam veterans without PTSD scored in a significantly more internal direction (M = 9.96, SD = 4.17) than those with PTSD (M= 17.0, SD = 6.1) on the Nowicki-Strickland Control Scale, a test of locus of control orientation (t,,,, = 5.73, p < .01). Veterans in the High Combat/No PTSD group (M = 9.87, SD = 4.13) scored in a significantly more internal direction than veterans in the High Combat/PTSD group (M = 16.44, SD = 6.08; t,,,,,= 4.28, p < .01) and those in the Moderate Combat/PTSD group (M = 24.33, SD = 3.07; t,,, = 7.37, p< .01).
Vietnam Veterans Experience Questionnaire A significant relationship was found between the presence or absence of PTSD and ability to have provided a structure to their experiences during their Vietnam tour, as assessed on the Vietnam Veterans Experience Questionnaire [X,2 (N = 107) = 6.63, p< .05]. Of Vietnam veterans without PTSD 72.7% endorsed more "structured" statements which indicated ability to have structured their Vietnam experiences, 16.9% of veterans without PTSD endorsed more "unstructured" statements whch indicated that they had been unable to do so, while 10.4% endorsed an equal amount of "structured" and "unstructured" statements. In contrast, 46.7% of Vietnam veterans with PTSD endorsed more statements which indicated that they had been able to structure their experiences during their Vietnam tour, 30.0% of the veterans with PTSD endorsed more statements indicating inability to have provided structure, and 23.3% of these veterans endorsed equal numbers of "structured" and "unstructured" statements. There were significant differences between the number of "structured" vs "unstructured" statements endorsed by veterans in the High Combat/ No PTSD group and the number endorsed by veterans in the High CombatlPTSD group [X,2 (N = 47) = 6.89, p < .05] as well as by veterans in the Moderate CombatlPTSD group [X,2 (N = 26) = 9.67, p < .01].
60 1
VIETNAM VETERANS WITH AND WITIHOUT PTSD
TABLE 3 PERCENTAGES OF VETERANSWHO ENDORSED MORE"STRUCTURED"vs MORE"UNSTRUCTURED" vs EQUAL NUMBERSOF "STRUCTURED" AND "UNSTRUCTURED" STATEMENTS ON VIETNAMVETERANSEXPERIENCE QLESTIOHNNRE AS A FUNCTION OF ABSENCE OR PRESENCE OF PTSD A N D AMOUNTOF COMBAT EXPOSURE Diagnosis Combat Gmup PTSD Absent High Moderate Low
PTSD Present High Moderate Low
n
Statements Endorsed "Structured" "Unstrucmred"
Equd
23 31 23
82.60 64.50 73.90
8.70 22.60 17.40
8.70 12.90 8.70
24 3 3
45.80 0.00 100.00
29.20 33.30 0.00
25.00 66.70 0.00
Resistance To Symptornatology As hypothesized, veterans exposed to high combat but who did not develop Posttraumatic Stress Disorder had the lowest mean Neuroticism score and displayed significantly lower Neuroticism than all groups with I he exception of the Moderate Combat/No PTSD and the Low Combat/PTSD groups. The mean Neuroticism score of the High Combat/No PTSD group was eight points lower than that of the Low Combat/PTSD group. Perhaps lack of significance was related to the small number of subjects in the Low Combat/PTSD group. [Few veterans met the criteria for placement in the Low Combat/PTSD and Moderate CombatlPTSD conditions. This most likely reflects the positive relationship consistently found between exposure to combat and the development of the disorder (Goldberg, - True, Eisen, & Henderson, 1990). Results pertaining to the latter two groups must be interpreted with caution.] The finding that high combat veterans without PTSD had significantly lower Neuroticism scores than low combat veterans without PTSD supports the notion that veterans who did not develop the disorder despite having a high combat exposure are individuals with exceptional emotional strength and resdiency. With regard to Psychoticism, veterans in the High Combat/No PTSD group had significantly lower Psychoticism than High Combat/PTSD and Moderate Combat/PTSD veterans only. There was a trend in the predicted direction, however, with veterans in the High Combat/No PTSD group having had the lowest mean Psychoticism score. By definition, the presence of an extreme stressor is necessary for and significantly correlated with the development of Posttraumatic Stress Disorder. It appears, however, that making accurate predictions about the pathology of an individual exposed to highly stressful conditions, based on
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L. CASELLA & R . W. MOTTA
knowledge of the intensity and duration of the stressor alone, is not possible. This is evident in the present data since a number of Vietnam veterans had been exposed to the greatest combat but did not develop the disorder, and for those without the disorder, greater exposure to combat stress was associated with less psychopathology than was less exposure. A significant relationship between exposure to combat and Neuroticism was found. Further analysis indicated that high combat veterans evidenced significantly more Neuroticism than moderate combat veterans. There were no significant differences, however, between Neuroticism evidenced by low combat veterans vs either high or moderate combat veterans. I n addition, no significant relationshp was found between amount of combat and Psychoticism. Numerous studies have indicated a strong relation between combat exposure and symptomatology of Posttraumatic Stress Disorder. Few researchers have looked at the relationship between combat exposure and other measures of pathology (Penk, Robinowitz, Roberts, Patterson, Dolan; & Atkins, 1981). The present study suggests that high combat is not consistently predictive of other pathology. This conclusion is supported by the findings of Hyer, O'Leary, Saucer, Blount, Harrison, and Boudewyns (1986).
Locus of Control Orientation As predicted, veterans without PTSD scored more internally on locus of control orientation than veterans with the disorder. Other researchers have reported that Vietnam veterans with PTSD are more likely to have an external locus of control than those without the disorder (Strayer & Ellenhorn, 1975; Frye & Stockton, 1982). Based on data indicating the locus of control orientation of veterans at the time of the study, a definitive conclusion cannot be reached about their locus of control orientations prior to or during the war. In addition, one can only speculate on the association between prewar locus of control orientation and the development of the symptomatology. Locus of control orientation may be unrelated to the acquisition of the disorder, but the disorder may lead one to experience one's self as being out of control and accordingly, to an external orientation. I t is also conceivable, however, that entering Vietnam with an external locus of control orientation led such individuals to deal with the war in a way that was conducive to the development of the symptoms. Conversely, the feeling of having some control over his own destiny, whether realistic or not, may have enabled the Vietnam soldier with an internal locus of control to cope more effectively with the experience. Accordingly, this orientation may have been helpful in preventing the development of Posttraumatic Stress Disorder.
Ability to Have Structured the Vietnam Experience Compared to veterans with PTSD, those without were more likely to have found ways to provide a cognitive structure to their experience during
VIETNAM VETERANS WITH AND WITHOUT PTSD
603
the time they were stationed in Vietnam, i.e., ways of organizing, conceptu&zing, and understanlng the experience. l h s result is similar to that reported by Hendin and Pollinger Haas (1984), who noted that the well-adjusted veterans had attempted to gain an understanding of the strategies of their missions while focusing on the limited objectives of each day. Hendin and Pollinger Haas concluded that such ways of structuring this chaotic experience helped these veterans to deal with the stress of the war in manageable, rational terms. I t is interesting to note that several writers on Nazi concentration camps have made reference to the role that providing meaning to extremely stressful situations plays relative to subsequent adjustment (Bettleheim, 1960; Frankl, 1962). An additional finding of the present study was that locus of control orientation was positively correlated with ability to structure the Vietnam experience. A plausible interpretation is that veterans who perceived themselves as having control over their destiny were motivated toward attempting to conceptuahze the Vietnam experience in meaningful, organized terms. These results suggest that this manner of coping with the war helped such veterans avoid developing Posttraumatic Stress Disorder. Conversely, veterans who believed that there was no connection between their actions and the consequences of those actions would conceivably have been overwhelmed by the constant threat to their survival over w h c h they perceived themselves as having no control. The latter perception appears associated with inability to conceptualize the war in manageable terms and ultimately, with the acquisition of symptoms of disorder. I t is believed that the significant relationship found between the presence or absence of the disorder and ability to structure one's Vietnam experience cognitively warrants further study. Additional ways to assess and to gain information about this variable should be explored. This could lead to the development of effective coping strategies for individuals facing extremely stressful circumstances.
Conclusion That some Vietnam veterans have not acquired Posttraumatic Stress Disorder despite high exposure to combat is notable. The findings of the present study indicating that high combat veterans with PTSD evidenced significantly less Neuroticism than low combat veterans without PTSD provide further evidence of their emotional resiliency or hardiness. Kobasa (1979) defined the concept of "hardiness" as a cluster of personality characteristics that function as a resistance resource in the encounter with stressful life events. Two characteristics proposed by Kobasa that relate to hardiness are commitment and control. Commitment relates to a generalized sense of purpose conducive to an inlvidual's finding meaning in the environment and is similar to the variable of providing structure to personal experience in the
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present study. The control dimension, like the concept of locus of control, is described as a tendency to feel and act as if one is influential in controlling the contingencies of life events. Most studies of hardiness, however, have dealt with individual reactions to common life stresses (Kobasa, 1979, 1982) and not with unusual stressors such as combat. Furthermore, the research literature relating to the concept of invulnerability (Anthony & Cohler, 1987) has focused upon children living under unusudy stressful conditions. Much could be learned from additional studies of groups of adults who have experienced extreme stressors without having prolonged or serious psychological consequences. Rather than viewing posttraumatic stress in terms of underlying weaknesses, it may be more valid and enlightening to focus upon the exceptional strengths demonstrated by such individuals. REFERENCES ANTHONY, E. J., & COHLER,B. J. (1987) The invulnerable child. New York: Guilford. BET~LEHEIM, B. (1960) The informed heart. New York: Avon. DEFAZIO,V. J., RUSTIN,S., & DIAMOND,A. (1975) Symptom development in Vietnam era veterans. American Journal of Orthopsychiatry, 45, 158-163. EGENDORF, A,, REMEZ,A., & FARLEY, J. (1981) Legacies of Vietnam: comparative adjustment of veterans and their peers. Vol. V . Dealing with the war: a view based on the individual lives of Vietnam veterans. New York: Center for Policy Research. EYSENCK, H . J., & EYSENCK, S. B. G . (1975) Eysenck Personality Questionnaire. San D~ego, CA: Educational & Industrial Testing Service. FOY, D. W., & CARD,J. J. (1987) Combat-related posttraumatic stress disorder etiology: replicated findings in a national sample of Vietnam-era men. Journal of Clinical Psychology, 43, 28-31.
FOY,D. W., SIPPRELLE, R. C., RUEGAR,D. B., & CARROLL, E. M. (1984) Etiology of osttraumatic stress disorder in Vietnam veterans: analysis of premilitary, military ancfcornbat exposure influences. lournal of Consulting and Clinical Psychology, 52, 79-87. FRANKL, V. E. (1962) Monk search for meaning: an introduction lo Logotherapy. Boston, MA: Beacon Press. FRYE,J. S., & STOCKTON, R. A. (1982) Discriminant analysis of posttraumatic stress disorder among a group of Vietnam veterans. American Journal of Psychiatry, 139, 52-56. GOLDBERG, J., TRUE,W. R., EISEN,S. A,, & HENDERSON, W. G . (1990) A twin study of the effects of the Vietnam war on posttraumatic stress disorder. Journal of /he American Medical Association, 263, 1227-1232. GOODWIN, D. W., DAVIS,D. H., & ROBINS,L. N. (1975) Drinking amid abundant illicit drugs. Archives of General Psychiatry, 32, 230-233. HENDM,H . , & POLLINGER HMS, A. (1984) Combat adaptation of Vietnam veterans without posttraumatic stress disorders. American Journal of Psychiatry, 141, 956-960. HYER,L., O'LEARY,W. C., SAUCER, R. T., BLOUNT, J., HARRISON, W. R., & BOUDEWYNS, P. A. (1986) Inpatient diagnosis of posttraumatic stress disorder. Iournal of Consulting and Clinical Psychology, 54, 698-702. KEANE, T. M., CADDELL,J. M., & TAYLOR,K. L. (1986) The Mississippi Scale for Combat-related PTSD. Boston, MA: VA Medical Center. and health: an inquiry into hardiness. KOBASA, S. C. (1979) Stressful life events Journal of Personality and Social Psychology, 37, 1-11. KOBASA, S. C. (1982) Hardiness and health: a prospective study. Journal of Personality and Social Psychology, 42, 168-177. LAUFER,R. S. (1988) Opportunities for intervention in the employment needs of Vietnam veterans in New York City. New York: Center for Policy Research.
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NACE,E. P., O'BRIEN, C. P., MINTZ,J. B., REAM, N., & MEYERS,A. L. (1978) Ad' amon Vietnam veteran drug users two ears post-service. In C. R. Figley ( E d ~ ~ s " ~ ~ ~ disorjmx among Vietnam veterans: tleory, research and treatment. New York: Brunner/Mazel. Pp. 71-128. NOWICKI, S., & D m , M. (1974) A locus of control scale for noncouege as well as college adults. Journal of Personalio Assessment, 38, 136-137. PEARCE,K. A . . SCMAUER, A. H., GARFIELD,N. ., OHLDE, C. O., & PATTERSON,T. N. (1985) A study o l posttraumatic stress disor er in Vietnam veterans. Journal of Clinical Psychologv, 41, 9-14. PENK, W. E , KOBMOWITZ, R., ROBERTS,W. R., PATTERSON,E. T., DOLAN,M. P., & ATKINS, H. B. (1981) Adjustment differences among male substance abusers varyin in degree of combat experience in Vietnam. Journal of Consulting and Clinical ~ s ~ c f o i 49, o~~, 426-437. SOLKOFF,N., GRAY,P., & KEILL, S. (1986) W h ~ c hVietnam veterans develop posttraumatic stress disorders? Journal of Clinical Psychology, 4 2 , 687-698. STRAYER,R., & ELLENHORN, L. (1975) Vietnam veterans: a scudy exploring adjustment patterns and attitudes. lournal of SociaiIssues, 3 1 , 81-93. WORTHINGTON, E. M. (1978) Demographic and pre-service variables as predictors of post-military service adjustment. In C. R. Figley (Ed.), Stress disorders among V i e m veterans: theory, research and treatment. New York: Brunner/Mazel. Pp, 173-187.
d
Accepted September G, 1990.
COMPARISON OF CHARACTERISTICS O F VIETNAM VETERANS WITH AND WITHOUT POSTTRAUMATIC STRESS DISORDER ' LAURAINE CASELLA AND ROBERT W. MOTTA
HoJstra University 3ztrnrnary.-Characteristics of 107 Vietnam veterans with and without Posttraumatic Stress Disorder (PTSD), who had been exposed to varying levels of combat, were compared. Severity of psychopathology as assessed on the Eysenck Personality Questionnaire, locus of control orientation as measured by the Nowicki-Strickland Internal-External Control Scale, and ability to have provided structure and meaning to the Vietnam experience were examined. Compared to veterans with Posttraumatic Stress Disorder, those without the disorder had lower Neuroticism and Psychoticism scores, were more internal in their locus of control orientation, and were more likely to have shown ability to provide structure to the Vietnam experience. The additional finding that veterans with high combat experience but without PTSD evidenced less neuroticism than low combat veterans without PTSD provides evidence that those who did not develop the disorder despite high exposure to combat stress are individuals with exceptional emotional strength and resilience.
Most research on the postwar adjustment of Vietnam veterans has focused on variables associated with the development of Posttraumatic Stress Disorder (PTSD) and other evidence of maladjustment. Numerous researchers have studied prernilitary, d t a r y , and postmditary adjustment factors associated with its development (Goodwin, Davis, & Robins, 1975; Nace, O'Brien, Mintz, Ream, & Meyers, 1978; Worthington, 1978). Many others, particularly more recent investigators, have emphasized the importance of extent of combat exposure in the acquisition of PTSD (DeFazio, Rustin, & Diamond, 1975; Foy & Card, 1987; Foy, Sipprelle, Ruegar, & Carroll, 1984; Pearce, Schauer, Garfield, Ohlde, & Patterson, 1985; Solkoff, Gray, & Keill, 1986). Few studies have focused more specifically upon veterans without PTSD and the identification of those factors which appear to have protected these individuals from experiencing long-term negative effects subsequent to their combat experiences. As part of a comprehensive investigation of Vietnam veterans, Egendorf, Remez, and Farley (1981) conducted a case-by-case study of the 5 to 10% of a sample of 169 Vietnam veterans who were determined to have attamed the highest level of occupational, interpersonal, and social adjustment. These researchers concluded that the well-adjusted Viet-
'Address correspondence to R. W. Motta, Ph.D., Department of Psychology, Monroe Hall, Hofstra University, Hempstead, NY 11550.
596
L. CASELLA
&
R. W. MOTTA
nam veterans in their sample were skilled problem solvers and tended to view difficult circumstances as a series of challenges. Also, they valued self-discipline and reported having felt some sense of responsibility for the conflict once in Vietnam. I n addition, Egendorf, et a/. (1981) maintained that these veterans were critical of the war and reported sensitivity to the Vietnamese that is atypical among Vietnam veterans over-all. Hendin and Haas (1984) offered the view that postwar adjustment should not be viewed only as a reflection of preexisting character strengths or weaknesses since some veterans who have evidenced postwar adjustment difficulties appear to have had healthy personality structures prior to having served in Vietnam. I n addition, they pointed out that some well-adjusted veterans have prewar histories of unstable family lives and have had little support upon their return from Vietnam. I n an introductory analysis, these investigators compared the combat adaptations of a group of 10 Vietnam veterans who had not developed the disorder with those of approximately 100 Vietnam veterans with the disorder. The factors that they cited as related to a positive postwar adjustment included having ability to function calmly under pressure, having an intellectual understanding of the objectives and strategies of missions, having the capability to cope with the war in terms of the limited objectives of each day's mission, and the ability to trust one's own judgment in making decisions about survival. The present research study compared on a number of relevant characteristics Vietnam veterans who have not developed Posttraumatic Stress Disorder with those who are suffering from the disorder. These include degree of psychological symptomatology, locus of control orientation, and ability to have provided a structure to the Vietnam experience. A primary focus was on Vietnam veterans without the disorder, particularly those exposed to high combat. I t was hypothesized that veterans exposed to more combat would score in the direction of more psychopathological symptomatology as measured on the Eysenck Personality Questionnaire than those in groups with less combat. I t was further hypothesized that in comparison to veterans who have not developed PTSD, those with the disorder would evidence more psychopathological symptomatology, score in the more external direction on the Nowicki-Strickland Control Scale, and be less likely to show ability to have provided their own structure to the often chaotic Vietnam experience as assessed by the Vietnam War Experience Questionnaire. Finally, it was hypothesized that in comparison to all other veteran groups, those who d o not suffer from PTSD despite high exposure to combat would evidence less psychopathological symptomatology, score in the more internal direction on locus of control, and be more likely to indicate ability to have provided a structure to the Vietnam war experience.
VIETNAM VETERANS WITH AND WITHOUT PTSD
Subjects The subjects were 107 male veterans of the Vietnam war who served between 1962 and 1973. They were recruited from a New York Veterans Administration Hospital and from four New York Vietnam Veterans centers. TABLE 1 CHARACTERISTICS OF SIX GROUPSIN VIETNAMVETERAN SAMPLE Characteristic
PTSD Absent High Moderate Low Combat Combat Combat
PTSD Present Low High Moderate Combat Combat Combat
Age n
M
SD Current Marital Status n % Single % Married % Separated/Divorced
Education n < High School, % High School Grad., % Some College or Trade, % College Grad., % Postgrad., % Employment Type, % n 1 2 3 4
5 6 7 8 Note.-1
= Professional and technical workers, 2 = Managers, officials, and proprietors, 3 = Clerical and sales, 4 = S u e d workers and Foremen, 5 = Semiskilled workers, 6 = Service workers, 7 = Laborers, unskilled workers, and 8 = Unemployed/retired.
The veterans' scores on the Mississippi Scale for Combat-related Posttraumatic Stress (Keane, Caddell, & Taylor, 1986) and The Combat Scale-Revised (Laufer, 1988) were used to place them into one of six groups. The groups were (1) veterans without PTSDIhigh combat exposure, (2) veterans without PTSD/moderate combat exposure, (3) veterans without PTSD/low combat exposure, (4) veterans with P T S D b g h combat exposure,
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L. CASELLA & R. W. MOTTA
(5) veterans with PTSDImoderate combat exposure, and (6) veterans with PTSD/low combat exposure. Procedure Testing was carried out individually and in groups, depending on the facility involved. Subjects were presented an assessment packet containing a demographic questionnaire and the remaining scales which they were instructed to return upon completion. Subjects were advised that the findings of the investigation would be made available to those who participated. Measures Mississippi Scale for Combat-related Posttraumatic Stress Disorder.-The Mississippi Scale for Combat-related PTSD (Keane, et al., 1986) is a 35-item scale derived from DSM-I11 criteria. Items are rated on a five-point Likert scale and summed to yield a total score which ranges from 35 to 175. A cut-off score of 107 was selected by the originators of the scale, since this cut-off gave accurate classification for 93% of Vietnam veterans with Posttraumatic Stress Disorder. Combat Scale-Revised.-The Combat Scale-Revised (Laufer, 1988) was used as a measure of combat exposure. I t consists of 15 hscrete events which are differentially weighted according to the severity of the experience. They yield an over-all score, ranging from 0 to 21, designed to quantify exposure to combat. Scores from 0 to 6 indicate low combat exposure, scores from 7 to 12 indlcate moderate combat exposure, and scores from 13 to 2 1 are indicative of high combat exposure. Eysenck Personality Questionnaire.-The Eysenck Personality Questionnaire (Eysenck & Eysenck, 1975) assesses various personality dimensions. The Neuroticism and Psychoticism subscales were used to measure psychopathological symptomatology. Nowicki-Strickland Internal-External Control Scale.-The Nowicki-Strickland Internal-External Control Scale for Adults (Nowicki & Duke, 1974) was designed as a measure of locus of control orientation or the extent to which an individual perceives that events are controlled by internal or external factors. Vietnam War Experience Questionnaire.-The Vietnam War Experience Questionnaire is a 10-item scale constructed for this study to assess the ability to have structured the Vietnam experience. The scale was validated by asking 10 individual raters to classify each item as either "structured" or "unstructured." "Structured" items were defined as those which indicated the abllity to have provided organization, conceptualization, or meaning to the experience. Examples of structured items are "The politics of the war were clear to me," h he way that I dealt with being in Vietnam was to concentrate on getting through one day at a time," and "My religious beliefs
599
VIETNAM VETERANS WITH AND WITHOUT PTSD
were what enabled me to get through each day." Examples of unstructured items are " W e I was stationed in Vietnam, I felt like I no longer knew who I was or what was important in my life" and "While in Vietnam I didn't know what was going on around me." There was 100% agreement on nine of the 10 items, with 80% agreement on the remaining item.
RESULTS The results are organized into sections representing data on each of the measures.
Eysenck Personality Questionnaire Veterans in the High Combat/No PTSD group (M = 8.39, SD = 4.81) had significantly lower Neuroticism scores than veterans in the High CombatlPTSD group (M = 18.71, SD = 3.61; t,,,,, = 8.29, p < .01), than veterans in the Moderate Combat/PTSD group (M = 19.67, SD = 2.52; t,,,, = 6.39, p< .01) and veterans in the Low Combat/No PTSD group (M = 11.78, SD = 5.99; t,, = 2.12, p< .05). TABLE 2 MEANSA N D STANDARD DEVIATIONS OF NEUROTICISM A N D PSYCHOTICISM SCORESO N EYSENCK PERSONNITY QLJESTIONNAIRE AS A FUNCTION OF ABSENCE OR PRESENCE OF PTSD AND LEVELOF C O ~ AEXPOSURE T Combat Group
n High M
23
8.39 4.81
2.61 2.15
23
18.71 3.61
7.67 3.54
31
9.19 5.24
2.90 1.80
3
19.67 2.52
8.67 1.53
23
11.78 6.00
3.13 2.56
3
17.00 4.36
10.00 4.58
SD Moderate M
Posttraumatic Stress Disorder Diagnosis Absent Diagnosis Present Neuroti- Psychotin Neuroti- Psychoticism cisrn cisrn cism
SD Law
M
SD Note.-Higher
scores indicate greater psychopathology
Analysis also indicated that veterans in the High CombatlNo PTSD group (M= 2.61, SD = 2.15) had significantly lower Psychoticism scores than veterans in the High CombatIPTSD group (M = 7.67, SD = 3.54; t,,,,, = 5.96, p< .OI) and veterans in the Moderate Combat/PTSD group (M = 8.67,
S D = 1.53; t,,,=6.12, p c . 0 1 ) . There were significant differences between combat groups based on their mean Neuroticism scores (F,,,,,= 3.16, p < .05). A post hoc comparison of means, using the Scheffi test, showed the High Combat group
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L. CASELLA & R. W. MOTTA
(M = 13.66, SD = 6.69) scored significantly higher than the Moderate Combat group (M = 10.12, SD = 5.87) and higher but not significantly differently from the Low Combat group (M = 12.38, SD = 6.0) on Neuroticism. In addition, the Scheffi test showed no significant difference between the mean Neuroticism scores of the Moderate Combat group and the Low Combat group. There were no significant differences among the mean Psychoticism scores of the High Combat (M = 5.19, SD = 3.87), Moderate Combat (M = 3.41, SD = 2.4 1) and Low Combat (M = 3.92, SD = 3.53) groups (F,,,,, = 2.96, p< .06). Nowicki-Strickland Control Scale Vietnam veterans without PTSD scored in a significantly more internal direction (M = 9.96, SD = 4.17) than those with PTSD (M= 17.0, SD = 6.1) on the Nowicki-Strickland Control Scale, a test of locus of control orientation (t,,,, = 5.73, p < .01). Veterans in the High Combat/No PTSD group (M = 9.87, SD = 4.13) scored in a significantly more internal direction than veterans in the High Combat/PTSD group (M = 16.44, SD = 6.08; t,,,,,= 4.28, p < .01) and those in the Moderate Combat/PTSD group (M = 24.33, SD = 3.07; t,,, = 7.37, p< .01).
Vietnam Veterans Experience Questionnaire A significant relationship was found between the presence or absence of PTSD and ability to have provided a structure to their experiences during their Vietnam tour, as assessed on the Vietnam Veterans Experience Questionnaire [X,2 (N = 107) = 6.63, p< .05]. Of Vietnam veterans without PTSD 72.7% endorsed more "structured" statements which indicated ability to have structured their Vietnam experiences, 16.9% of veterans without PTSD endorsed more "unstructured" statements whch indicated that they had been unable to do so, while 10.4% endorsed an equal amount of "structured" and "unstructured" statements. In contrast, 46.7% of Vietnam veterans with PTSD endorsed more statements which indicated that they had been able to structure their experiences during their Vietnam tour, 30.0% of the veterans with PTSD endorsed more statements indicating inability to have provided structure, and 23.3% of these veterans endorsed equal numbers of "structured" and "unstructured" statements. There were significant differences between the number of "structured" vs "unstructured" statements endorsed by veterans in the High Combat/ No PTSD group and the number endorsed by veterans in the High CombatlPTSD group [X,2 (N = 47) = 6.89, p < .05] as well as by veterans in the Moderate CombatlPTSD group [X,2 (N = 26) = 9.67, p < .01].
60 1
VIETNAM VETERANS WITH AND WITIHOUT PTSD
TABLE 3 PERCENTAGES OF VETERANSWHO ENDORSED MORE"STRUCTURED"vs MORE"UNSTRUCTURED" vs EQUAL NUMBERSOF "STRUCTURED" AND "UNSTRUCTURED" STATEMENTS ON VIETNAMVETERANSEXPERIENCE QLESTIOHNNRE AS A FUNCTION OF ABSENCE OR PRESENCE OF PTSD A N D AMOUNTOF COMBAT EXPOSURE Diagnosis Combat Gmup PTSD Absent High Moderate Low
PTSD Present High Moderate Low
n
Statements Endorsed "Structured" "Unstrucmred"
Equd
23 31 23
82.60 64.50 73.90
8.70 22.60 17.40
8.70 12.90 8.70
24 3 3
45.80 0.00 100.00
29.20 33.30 0.00
25.00 66.70 0.00
Resistance To Symptornatology As hypothesized, veterans exposed to high combat but who did not develop Posttraumatic Stress Disorder had the lowest mean Neuroticism score and displayed significantly lower Neuroticism than all groups with I he exception of the Moderate Combat/No PTSD and the Low Combat/PTSD groups. The mean Neuroticism score of the High Combat/No PTSD group was eight points lower than that of the Low Combat/PTSD group. Perhaps lack of significance was related to the small number of subjects in the Low Combat/PTSD group. [Few veterans met the criteria for placement in the Low Combat/PTSD and Moderate CombatlPTSD conditions. This most likely reflects the positive relationship consistently found between exposure to combat and the development of the disorder (Goldberg, - True, Eisen, & Henderson, 1990). Results pertaining to the latter two groups must be interpreted with caution.] The finding that high combat veterans without PTSD had significantly lower Neuroticism scores than low combat veterans without PTSD supports the notion that veterans who did not develop the disorder despite having a high combat exposure are individuals with exceptional emotional strength and resdiency. With regard to Psychoticism, veterans in the High Combat/No PTSD group had significantly lower Psychoticism than High Combat/PTSD and Moderate Combat/PTSD veterans only. There was a trend in the predicted direction, however, with veterans in the High Combat/No PTSD group having had the lowest mean Psychoticism score. By definition, the presence of an extreme stressor is necessary for and significantly correlated with the development of Posttraumatic Stress Disorder. It appears, however, that making accurate predictions about the pathology of an individual exposed to highly stressful conditions, based on
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L. CASELLA & R . W. MOTTA
knowledge of the intensity and duration of the stressor alone, is not possible. This is evident in the present data since a number of Vietnam veterans had been exposed to the greatest combat but did not develop the disorder, and for those without the disorder, greater exposure to combat stress was associated with less psychopathology than was less exposure. A significant relationship between exposure to combat and Neuroticism was found. Further analysis indicated that high combat veterans evidenced significantly more Neuroticism than moderate combat veterans. There were no significant differences, however, between Neuroticism evidenced by low combat veterans vs either high or moderate combat veterans. I n addition, no significant relationshp was found between amount of combat and Psychoticism. Numerous studies have indicated a strong relation between combat exposure and symptomatology of Posttraumatic Stress Disorder. Few researchers have looked at the relationship between combat exposure and other measures of pathology (Penk, Robinowitz, Roberts, Patterson, Dolan; & Atkins, 1981). The present study suggests that high combat is not consistently predictive of other pathology. This conclusion is supported by the findings of Hyer, O'Leary, Saucer, Blount, Harrison, and Boudewyns (1986).
Locus of Control Orientation As predicted, veterans without PTSD scored more internally on locus of control orientation than veterans with the disorder. Other researchers have reported that Vietnam veterans with PTSD are more likely to have an external locus of control than those without the disorder (Strayer & Ellenhorn, 1975; Frye & Stockton, 1982). Based on data indicating the locus of control orientation of veterans at the time of the study, a definitive conclusion cannot be reached about their locus of control orientations prior to or during the war. In addition, one can only speculate on the association between prewar locus of control orientation and the development of the symptomatology. Locus of control orientation may be unrelated to the acquisition of the disorder, but the disorder may lead one to experience one's self as being out of control and accordingly, to an external orientation. I t is also conceivable, however, that entering Vietnam with an external locus of control orientation led such individuals to deal with the war in a way that was conducive to the development of the symptoms. Conversely, the feeling of having some control over his own destiny, whether realistic or not, may have enabled the Vietnam soldier with an internal locus of control to cope more effectively with the experience. Accordingly, this orientation may have been helpful in preventing the development of Posttraumatic Stress Disorder.
Ability to Have Structured the Vietnam Experience Compared to veterans with PTSD, those without were more likely to have found ways to provide a cognitive structure to their experience during
VIETNAM VETERANS WITH AND WITHOUT PTSD
603
the time they were stationed in Vietnam, i.e., ways of organizing, conceptu&zing, and understanlng the experience. l h s result is similar to that reported by Hendin and Pollinger Haas (1984), who noted that the well-adjusted veterans had attempted to gain an understanding of the strategies of their missions while focusing on the limited objectives of each day. Hendin and Pollinger Haas concluded that such ways of structuring this chaotic experience helped these veterans to deal with the stress of the war in manageable, rational terms. I t is interesting to note that several writers on Nazi concentration camps have made reference to the role that providing meaning to extremely stressful situations plays relative to subsequent adjustment (Bettleheim, 1960; Frankl, 1962). An additional finding of the present study was that locus of control orientation was positively correlated with ability to structure the Vietnam experience. A plausible interpretation is that veterans who perceived themselves as having control over their destiny were motivated toward attempting to conceptuahze the Vietnam experience in meaningful, organized terms. These results suggest that this manner of coping with the war helped such veterans avoid developing Posttraumatic Stress Disorder. Conversely, veterans who believed that there was no connection between their actions and the consequences of those actions would conceivably have been overwhelmed by the constant threat to their survival over w h c h they perceived themselves as having no control. The latter perception appears associated with inability to conceptualize the war in manageable terms and ultimately, with the acquisition of symptoms of disorder. I t is believed that the significant relationship found between the presence or absence of the disorder and ability to structure one's Vietnam experience cognitively warrants further study. Additional ways to assess and to gain information about this variable should be explored. This could lead to the development of effective coping strategies for individuals facing extremely stressful circumstances.
Conclusion That some Vietnam veterans have not acquired Posttraumatic Stress Disorder despite high exposure to combat is notable. The findings of the present study indicating that high combat veterans with PTSD evidenced significantly less Neuroticism than low combat veterans without PTSD provide further evidence of their emotional resiliency or hardiness. Kobasa (1979) defined the concept of "hardiness" as a cluster of personality characteristics that function as a resistance resource in the encounter with stressful life events. Two characteristics proposed by Kobasa that relate to hardiness are commitment and control. Commitment relates to a generalized sense of purpose conducive to an inlvidual's finding meaning in the environment and is similar to the variable of providing structure to personal experience in the
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present study. The control dimension, like the concept of locus of control, is described as a tendency to feel and act as if one is influential in controlling the contingencies of life events. Most studies of hardiness, however, have dealt with individual reactions to common life stresses (Kobasa, 1979, 1982) and not with unusual stressors such as combat. Furthermore, the research literature relating to the concept of invulnerability (Anthony & Cohler, 1987) has focused upon children living under unusudy stressful conditions. Much could be learned from additional studies of groups of adults who have experienced extreme stressors without having prolonged or serious psychological consequences. Rather than viewing posttraumatic stress in terms of underlying weaknesses, it may be more valid and enlightening to focus upon the exceptional strengths demonstrated by such individuals. REFERENCES ANTHONY, E. J., & COHLER,B. J. (1987) The invulnerable child. New York: Guilford. BET~LEHEIM, B. (1960) The informed heart. New York: Avon. DEFAZIO,V. J., RUSTIN,S., & DIAMOND,A. (1975) Symptom development in Vietnam era veterans. American Journal of Orthopsychiatry, 45, 158-163. EGENDORF, A,, REMEZ,A., & FARLEY, J. (1981) Legacies of Vietnam: comparative adjustment of veterans and their peers. Vol. V . Dealing with the war: a view based on the individual lives of Vietnam veterans. New York: Center for Policy Research. EYSENCK, H . J., & EYSENCK, S. B. G . (1975) Eysenck Personality Questionnaire. San D~ego, CA: Educational & Industrial Testing Service. FOY, D. W., & CARD,J. J. (1987) Combat-related posttraumatic stress disorder etiology: replicated findings in a national sample of Vietnam-era men. Journal of Clinical Psychology, 43, 28-31.
FOY,D. W., SIPPRELLE, R. C., RUEGAR,D. B., & CARROLL, E. M. (1984) Etiology of osttraumatic stress disorder in Vietnam veterans: analysis of premilitary, military ancfcornbat exposure influences. lournal of Consulting and Clinical Psychology, 52, 79-87. FRANKL, V. E. (1962) Monk search for meaning: an introduction lo Logotherapy. Boston, MA: Beacon Press. FRYE,J. S., & STOCKTON, R. A. (1982) Discriminant analysis of posttraumatic stress disorder among a group of Vietnam veterans. American Journal of Psychiatry, 139, 52-56. GOLDBERG, J., TRUE,W. R., EISEN,S. A,, & HENDERSON, W. G . (1990) A twin study of the effects of the Vietnam war on posttraumatic stress disorder. Journal of /he American Medical Association, 263, 1227-1232. GOODWIN, D. W., DAVIS,D. H., & ROBINS,L. N. (1975) Drinking amid abundant illicit drugs. Archives of General Psychiatry, 32, 230-233. HENDM,H . , & POLLINGER HMS, A. (1984) Combat adaptation of Vietnam veterans without posttraumatic stress disorders. American Journal of Psychiatry, 141, 956-960. HYER,L., O'LEARY,W. C., SAUCER, R. T., BLOUNT, J., HARRISON, W. R., & BOUDEWYNS, P. A. (1986) Inpatient diagnosis of posttraumatic stress disorder. Iournal of Consulting and Clinical Psychology, 54, 698-702. KEANE, T. M., CADDELL,J. M., & TAYLOR,K. L. (1986) The Mississippi Scale for Combat-related PTSD. Boston, MA: VA Medical Center. and health: an inquiry into hardiness. KOBASA, S. C. (1979) Stressful life events Journal of Personality and Social Psychology, 37, 1-11. KOBASA, S. C. (1982) Hardiness and health: a prospective study. Journal of Personality and Social Psychology, 42, 168-177. LAUFER,R. S. (1988) Opportunities for intervention in the employment needs of Vietnam veterans in New York City. New York: Center for Policy Research.
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NACE,E. P., O'BRIEN, C. P., MINTZ,J. B., REAM, N., & MEYERS,A. L. (1978) Ad' amon Vietnam veteran drug users two ears post-service. In C. R. Figley ( E d ~ ~ s " ~ ~ ~ disorjmx among Vietnam veterans: tleory, research and treatment. New York: Brunner/Mazel. Pp. 71-128. NOWICKI, S., & D m , M. (1974) A locus of control scale for noncouege as well as college adults. Journal of Personalio Assessment, 38, 136-137. PEARCE,K. A . . SCMAUER, A. H., GARFIELD,N. ., OHLDE, C. O., & PATTERSON,T. N. (1985) A study o l posttraumatic stress disor er in Vietnam veterans. Journal of Clinical Psychologv, 41, 9-14. PENK, W. E , KOBMOWITZ, R., ROBERTS,W. R., PATTERSON,E. T., DOLAN,M. P., & ATKINS, H. B. (1981) Adjustment differences among male substance abusers varyin in degree of combat experience in Vietnam. Journal of Consulting and Clinical ~ s ~ c f o i 49, o~~, 426-437. SOLKOFF,N., GRAY,P., & KEILL, S. (1986) W h ~ c hVietnam veterans develop posttraumatic stress disorders? Journal of Clinical Psychology, 4 2 , 687-698. STRAYER,R., & ELLENHORN, L. (1975) Vietnam veterans: a scudy exploring adjustment patterns and attitudes. lournal of SociaiIssues, 3 1 , 81-93. WORTHINGTON, E. M. (1978) Demographic and pre-service variables as predictors of post-military service adjustment. In C. R. Figley (Ed.), Stress disorders among V i e m veterans: theory, research and treatment. New York: Brunner/Mazel. Pp, 173-187.
d
Accepted September G, 1990.
