Combat Exposure and Posttraumatic Stress Disorder Among Portuguese Special Operation Forces Deployed in Afghanistan

Transcription

1 Military Psychology 2013 American Psychological Association 2013, Vol. 25, No. 1, /13/$12.00 DOI: /h Combat Exposure and Posttraumatic Stress Disorder Among Portuguese Special Operation Forces Deployed in Afghanistan Carlos Osório University of Minho Neil Greenberg, Norman Jones, Laura Goodwin, and Mohammed Fertout King s College London Ângela Maia University of Minho Several combat- and noncombat-related stressors have been reported in Afghanistan. There is now accumulating evidence that suggests that posttraumatic stress disorder (PTSD) is linked to combat experiences; however, little is known about how these exposures might affect elite combat troops. This research aims to evaluate the prevalence of combat and noncombat related stressors, as well as PTSD in Portuguese Special Forces deployed in Afghanistan. Overall, participants reported high levels of exposure to combat and adverse physical conditions but also high levels of within-unit comradeship. The analysis also exposed that 2.7% of the participants reported symptoms compatible with PTSD and 8.8% with compatible partial PTSD. When the authors conducted a binary logistic regression, only the higher levels of combat exposure explained the symptoms of PTSD. Keywords: PTSD, combat, Afghanistan, Special Operation Forces, Portuguese army Since the beginning of the Global War on Terror, various coalition countries have contributed military Special Operation Forces (SOFs) to combat operations in Afghanistan (Hing, Cabrera, Barstow, & Forsten, 2012; Neville & Bujeiro, 2008). Soldiers from SOFs will generally undertake hazardous military duties, including reconnaissance and direct and indirect combat operations often against a sometimes resourceful enemy. They undertake these operations in remote areas for extended periods of time with little external support (Hing et al., 2012; Neville & Bujeiro, 2008). Carlos Osório, School of Psychology, University of Minho, Braga, Portugal; Neil Greenberg, Norman Jones, Laura Goodwin, and Mohammed Fertout, Institute of Psychiatry, Academic Centre for Defence Mental Health, King s College London, London, England; Ângela Maia, School of Psychology, University of Minho. The views and opinions expressed in this article are solely those of the authors. Correspondence concerning this article should be addressed to Carlos Osório, School of Psychology, University of Minho, Campus de Gualtar, Braga, Portugal. carlos.m.osorio81@gmail.com Members of SOF personnel characterize the most elite of military forces and during military training its members underwent a multiple rigorous training program, including a highly stressful selection and assessment course, which prepares them for the future potential adverse circumstances of combat deployments (Bartone, Roland, Picano, & Williams, 2008). By studying members of SOF personnel and their regular counterparts in realistic training scenarios (e.g., Survival Evasion, Resistance and Escape [SERE] school) studies revealed that SOF personnel exhibited an enhanced biobehavioral mechanism of response to stressful circumstances, rebounded more quickly from these challenging experiences, and were less prone to dissociation (Bartone et al., 2008; Morgan et al., 2000; Morgan, Hazlett, et al., 2001; Morgan, Wang, et al., 2001). In 2005, Portugal started sending army personnel to Afghanistan as a result of the Bonn Convention. Soldiers were deployed as company sized units (approximately 160 men) and were mostly drawn from SOFs, the commando unit. Portuguese SOFs main role in Afghanistan was to reinforce the quick reaction force (QRF) 70

2 COMBAT EXPOSURE AND PTSD 71 as part of international security assistance force (ISAF) and to carry duties such as surveillance, security, and combat patrols (Bartolomeu, 2008). The Afghanistan campaign has seen coalition troops carrying out counterinsurgency (COIN) operations, whereby the operational theater lacks obvious frontlines, and military personnel are frequently exposed to combat events such as ambush, suicide attacks, and encountering improvised explosive devices (IEDs; Fear et al., 2010; Hoge et al., 2004). There is a wealth of research, which suggests that many soldiers, particularly those deployed in a combat role, are frequently exposed to severe traumatic events including being wounded, opening fire at the enemy and seeing or handling human remains (Fear et al., 2010; Hoge et al., 2004). Current evidence within regular military forces suggests that prolonged exposure to combat experiences such as these is often associated with an increased risk of mental health problems such as posttraumatic stress disorder (PTSD), and symptoms are often proportional to the levels of reported combat (Fear et al., 2010; Hoge et al., 2004). In surveys of U.S. military personnel evaluated after their return from deployment, 11.5% of personnel in Army Units deployed to Afghanistan developed PTSD, as did 18.0% of personnel in Army Units and 19.9% of those in Marine units deployed to Iraq (Hoge et al., 2004). Similar results were also obtained with a group of Marines who returned from both theaters of war where an estimated 17.1% of personnel reported symptoms of PTSD (Booth- Kewley, Larson, Highfill-McRoy, Garland, & Gaskin, 2010). However, other coalition nations report significantly lower levels of PTSD, such as in the United Kingdom, where rates of 4.7% in Army Units and 2.0% in the Royal Marines Commandos have been reported (Iversen et al., 2008). In regard to members of SOF personnel, research is inconsistent and scarce. A recent study with U.S. SOF personnel who returned from Afghanistan, Iraq, Philippines and other places showed that between 16% and 20% of respondents met scoring threshold for PTSD (Hing et al., 2012). Similar results were also reported with U.S. Special Forces veterans from the Vietnam conflict, where rates of PTSD were 25% (Chemtob et al., 1990). However, the Sri Lanka Special Forces personnel reported a lower prevalence rate of 1.9% (Hanwella & De Silva, 2012), and another study of U.S. SOF personnel deployed in Iraq suggested a prevalence rate of 8.8% (Espinoza, 2010). There have been many studies that have evaluated the effects of deployment on PTSD; however, its variability in rates made interpretation difficult to compare between different military forces. Previous reviews have attributed some variability in PTSD rate to the sampling strategy (random vs. nonrandom selection), type of assessment (anonymous vs. nonanonymous surveys), and distinct combat military units with distinct combat rates (Kok, Herrell, Thomas, & Hoge, 2012; Sundin, Fear, Iversen, Rona, & Wessely, 2010). Nevertheless, given the lack of studies that addressed members of SOF personnel, from our perspective it seemed advisable to include studies regarding the prevalence rate of PTSD with the objective of providing a general panorama of the problem within regular military units recently returned from operational deployments, such as Afghanistan. Prior studies within military forces suggest that combat exposure is not the only determinant of PTSD in regular military personnel, and there is some evidence that PTSD may be also associated with factors such as experiencing noncombat-related stressors while deployed (Booth-Kewley et al., 2010; King, King, Gudanowski, & Vreven, 1995; Litz, King, King, Orsillo, & Friedman, 1997), longer deployment duration, and undertaking a higher number of deployments (Adler, Huffman, Bliese, & Castro, 2005; Castro, Adler, & Huffman, 1999). A number of studies suggest that deployment-related stressors (Booth-Kewley et al., 2010), low-level military-related stressors (Litz et al., 1997), unit cohesion and leadership (Mulligan et al., 2010), and malevolent environment stressors (King et al., 1995) all affect mental health outcomes. Given the diversity of what should be regarded as a noncombat related stressor, we have chosen to focus on adverse physical conditions (e.g., lack of water food, excessive cold heat temperature, lack of privacy, poor sleeping conditions) and also unitrelated problems (e.g., inadequate military equipment, leadership, lack of a meaningful work, boredom), and their effects on the development of PTSD symptomatology personnel deployed in Afghanistan. Recent studies conducted with U.S. military forces suggest that soldiers completing their

3 72 OSÓRIO ET AL. second through to fourth deployment in Afghanistan and Iraq are more likely to report more PTSD symptoms than soldiers on their first deployment (Mental Health Advisory Team, 2011). The same findings were also observed within members of U.S. SOF personnel after their third deployment in Afghanistan (Hing et al., 2012). In contrast, a U.K. study of military personnel who had deployed to Afghanistan and/or Iraq did not find any significant relationship between multiple deployments and PTSD (Fear et al., 2010). Much of the available research examines the effects of deployment on the mental health of deployed regular military forces; however, to our knowledge little research has been conducted with personnel from elite forces deployed in Afghanistan. Given that members from special forces are more likely to be engaged in intense combat operations, to experience a greater number of noncombat-related stressors as a consequence of the way in which they are deployed, and also to be deployed on multiple tours of duty, two main objectives were established for this study. Our first objective was to determine the prevalence rate of combat- and noncombat-related stressors, number of deployments, and PTSD symptoms among Portuguese SOF Commandos who deployed to Afghanistan. Our second objective was to examine whether rates of combat exposure and noncombat-related stressors were associated with PTSD. Participants Method 113 Portuguese army SOFs who completed at least one deployment of 6 months in Afghanistan (standard Portuguese military deployment) between the periods of 2005 and 2010 participated in the study. All participants had served in the Commando Battalion (1st and 2nd company of Commandos), and all had been discharged from the military. The period between returning from deployment and participation in the survey varied from 6 months to 4 years. Participants had a mean age of 26.7 years (SD 3.3; range 21 36), two thirds were single, the majority had not taken part in college education, most ( 80%) were junior ranks, and over half had undertaken more than one deployment (see Table 1). Measures Table 1 Sociodemographic and Military Characteristics A questionnaire was developed and used to evaluate demographic information, including age; marital status; education; military characteristics, such as rank; and the number and length of deployments. A combat and deployment experience scale was adapted from the Portuguese Military History Questionnaire (Maia, McIntyre, Pereira, & Ribeiro, 2011), which assessed both combatand noncombat-related stressors. The scale in- Variable n % Marital status Single Informal union or marriage Divorced Education Intermediate or high school diploma Attendance of college degree Rank E1 E4 (Private to Corporal) E5 E8 (Sergeant to First Sergeant) O1 02 (Second Lieutenant to First Lieutenant) No. of deployment

4 COMBAT EXPOSURE AND PTSD 73 cluded two sections. The first part comprised 17-dichotomous items that assessed the presence or absence of several combat situations, such as seeing wounded and or dead bodies, killing the enemy, receiving hostile reactions from local people, and being injured. The scale was scored from 0 17, where higher cumulative values represented exposure to more combat events. An overall combat experience index was created by adding together all subscale items. The second section assessed noncombat-related situations in two independent categories and included adverse physical conditions and unit-related problems. The first category consisted of nine dichotomous items that assessed the absence or presence of adverse physical conditions, such as experiencing lack of water or food, excessive climatic conditions, and lack of sleep. The subscale ranged from a minimum of zero to a maximum of nine experiences, where greater values signified more frequent exposure. An overall adverse physical condition index was created by adding together all subscale items. The second category consisted of 11 items in a 3-point Likert-type scale, ranging from 1 (low) to 3(high), which assessed unit-related factors such as the quality of leadership, unit cohesion, and military training. The subscale ranged from a minimum score of 11 to a maximum of 33, in which lower values signified poorer unit conditions. An overall unit-related problems index was created by summating all subscale items. Posttraumatic stress disorder symptoms were measured by using the 17-item Response to Traumatic Event Scale (RTES; McIntyre & Ventura, 1996), which evaluates the presence or absence PTSD symptom according to the Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM IV TR, American Psychiatric Association, 1994). A positive PTSD case was identified if participants reported at least one reexperience symptom, three avoidance symptoms, and two hyperarousal symptoms (McIntyre & Ventura, 1996). Partial PTSD was identified if participants reported at least one reexperiencing symptom, one avoidance or one hyperarousal symptom, or if they reported at least one reexperiencing symptom and either three avoidance or two hyperarousal symptoms (Kulka et al., 1990; Schnurr et al., 2000). The internal consistency of the standardized instrument, as measured by Cronbach s alpha (.83) suggested good internal reliability. Procedure We contacted a total of 232 military veterans from an assumed full estimated population of 500 Portuguese SOFs Commandos that were deployed to Afghanistan between the years of 2005 and At the time of the research, all participants had been discharged from the military. As the Portuguese Government does not publish the names of soldiers on military operations, we adopted a snowball sampling method. We initially contacted two former SOFs veterans, who gave the contact details of other personnel who we subsequently contacted, and the process was repeated. All participants were contacted by telephone or mail between March 2010 and February 2011 and were informed about the objectives of the research, that their personal information would be completely confidential, and that this research was not associated with any ongoing army assessment. Those participants who showed an interest in participating in the research were asked to provide their address so the questionnaires could be mailed to them. Of the total sample initially contacted, only 123 returned their self-reported survey. Reasons for nonresponse included not answering the telephone or mail invitation (n 47; 20.3%), declining to participate (n 15; 6.5%), providing an insufficient or incorrect address (n 13; 5.6%), or dropping out of the study (n 34; 14.6%). One hundred twenty-three participants returned the self-reported questionnaire, which is a 53% response rate; however, an additional 10 had to be excluded for not answering several questions. The final response rate was 48.7%. This study received approval from the University of Minho Local Institutional Review Board for the Protection of Human Subjects in alignment with the principles outlined in the American Psychological Association (APA) Publication Manual. Data Analysis All descriptive and inferential analyses were performed by using the Statistical Software Package for Social Sciences (SPSS; Version 17) for Windows. Frequencies and descriptive statistics were generated for each of the combat

5 74 OSÓRIO ET AL. events experienced, for the number of adverse physical conditions reported, and also for personnel who screened positive for PTSD and partial PTSD. For examining the association between combat exposure, adverse physical conditions, PTSD, and other key variables, we carried out bivariate analyses. The exploratory analysis suggested that the criteria for parametric tests were not satisfied so we used the equivalent nonparametric analysis (Spearman correlation test). To assess the effect of both combat exposure and adverse noncombat events upon PTSD symptoms, we generated tertiles for both of these variables and combined the middle and lower tertiles, which were compared with the upper tertile. We then conducted a Mann Whitney U test to compare subgroup differences in PTSD scores in those who reported higher and lower middle levels of combat exposure and adverse physical conditions. The rationale underlying the Mann Whitney U test was to look at differences in the ranked positions of PTSD scores in the different subgroups. Last, unadjusted and adjusted binary logistic regression was used to generate odds ratio (OR) and 95% confidence intervals (95% CI) to examine the effect of combat experiences, adverse physical conditions, and a range of sociodemographic and military factors on PTSD symptoms (tertile splits were conducted and the upper tertile was compared with the combined lower and middle tertiles). These analyses aimed to examine whether PTSD was associated with combat exposure and adverse physical conditions after adjustment for the demographic and military variables. Results The majority of participants endorsed multiple combat experiences during their deployment in Afghanistan (M 8, SD 3.10; range 1 15). The most frequently reported combat experiences were those associated with death and injury, and the least frequently reported combat experiences were being injured personally, seeing Portuguese individuals dead, and killing enemy combatants. For noncombat experiences, an average of four adverse physical conditions were reported (SD 1.92; range 0 8). The most frequent adverse physical experiences were discomfort and unbearable weather, and the least frequent were experiencing starvation and thirst. The majority of participants reported high levels of unit cohesion, good leadership, and good social support (M 28.17, SD 3.22; range 17 33; see Table 2). The prevalence of probable PTSD was 2.7% (n 3) and for partial PTSD, 8.8% (n 10). The number of PTSD symptoms ranged from a minimum of zero to a maximum of 11 symptoms (M 1.46, SD 2.42). Neither combat experiences nor adverse physical experiences were significantly associated with PTSD caseness. Adverse physical conditions were strongly correlated with combat experiences, number of deployments, and PTSD symptoms and negatively correlated with unit related problems, whereas combat experiences were also correlated with number of deployments and PTSD symptoms in addition to adverse physical conditions (see Table 3). The association between level of combat exposure and adverse physical conditions with PTSD symptoms were compared by using Mann Whitney U tests. The results suggested that those who reported high levels of both combat exposure (p.01) and adverse physical conditions (p.01) were significantly more likely to report PTSD symptoms, compared with those who reported low and middle levels, when the PTSD scores were treated as a continuous variable (see Table 4). The multivariate analyses suggested that only combat experiences were significantly associated with being in the upper tertile for reporting PTSD symptoms after adjustment for a range of demographic, operational, and military confounders (see Table 5). Discussion In this article, we report the first examination of the effects of deployment on Portuguese SOF Commandos while serving in Afghanistan. Our findings suggest that Portuguese troops reported numerous intense combat experiences, including wounding and killing enemies, helping wounded fellow soldiers, or being injured or wounded themselves. However, our data also suggest that troops also reported being exposed to numerous noncombat related stressors such as adverse weather conditions, a lack of sleep, and poor diet. Nevertheless, in spite of these

6 COMBAT EXPOSURE AND PTSD 75 Table 2 Combat Experiences, Adverse Physical Conditions, and Unit-Related Problems Combat experiences n % Seeing wounded civilians Knowing wounded coalition military Knowing killed coalition military Seeing wounded enemies Knowing wounded Portuguese military In an operation where risked death Knowing Portuguese killed military IED exploding near your combat unit Having hostile reactions from civilians Feeling of no safe place in theater Carrying wounded Portuguese military Seeing killed enemies Having wounded enemies in combat actions Seeing dead Portuguese military Having killed enemies in combat actions Being injured as a result of combat actions Adverse physical conditions Uncomfortable (humidity heat) weather Unbearable weather Eaten spoiled or out-of-order food water Problems with the amount of hours to sleep Experience several days without sleep Lack of food water Eat overly based food rations Had bad sleep as a result of inappropriate conditions Starvation Thirst Unit-related problems Low (n) % Medium (n) % High (n) % Union between the comrades in unit (0) 0.0 (14) 12.4 (99) 87.6 Support given by superior in unit (22) 19.5 (36) 31.9 (55) 48.7 Discipline imposed in unit (2) 1.8 (21) 18.6 (90) 79.6 Pride to belong to unit (1) 0.9 (4) 3.5 (108) 95.6 Acceptance by comrades in unit (0) 0.0 (19) 16.8 (94) 83.2 Commitment to the unit objectives (1) 0.9 (13) 11.5 (99) 87.6 Superior leadership in unit regarding decisions, orders, or rules (19) 16.8 (50) 44.2 (44) 38.9 Quality of military training received in unit (3) 2.7 (16) 14.2 (94) 83.2 Quality of the military equipment regarding weapons and ammunition (21) 18.6 (79) 69.9 (13) 11.5 Military training appropriate or informative for the type of missions realized in theater (21) 18.6 (79) 69.9 (13) 11.5 Agreement with the strategies used in the unit (6) 5.3 (58) 51.3 (49) 43.4 challenges, most reported good levels of unit satisfaction, and they also considered that their military training had been of high standard. These findings are not altogether unsurprising given that the sample was composed of special forces personnel who normally undertake the most arduous of missions. The prevalence of PTSD in this study was low, with 2.7% of personnel reporting PTSD caseness. These results are similar to those obtained from a group of U.K. Royal Marines Commandos deployed in Iraq, and a group of U.S. personnel not exposed to combat, where caseness rates ranged from 1.4% to 2.1% (Iversen et al., 2008; Smith et al., 2008). In terms of special forces, the only study to our knowledge that reported a similar PTSD rate (1.9%) was described with members from the Sri Lanka Special Forces personnel after one year of deployment (Hanwella & De Silva,

7 76 OSÓRIO ET AL. Table 3 Spearman Correlation Test Among the Studied Variables Variable M SD Age Combat experiences Adverse physical condition Unit-related problems Number of deployments PTSD symptoms Note. PTSD posttraumatic stress disorder. p.01. p ). For the partial PTSD rates in this study are also lower than those found in U.S. studies where rates ranged from 17.9% to 22.3% (Jakupcak et al., 2007; Pietrzak, Goldstein, Malley, Johnson, & Southwick, 2009). Due to the lack of comparable data with special forces veterans, we opted to compare our data with other military samples most of them in active duty acknowledging that studies developed with veterans personnel suggest that this group is normally less healthier and more emotionally distressed (Kulka et al., 1990; Richardson, Engel, Hunt, McKnight, & Fall, 2002; Shalev, Bleich, & Ursano, 1990). Despite the relatively high levels of combat exposure reported in this study, the levels of experiencing combat actions such as responsibility in killing an enemy combatant or being wounded injured are quite similar to those reported by other coalition forces in Afghanistan; however, in general, our rates of PTSD are somewhat lower (Hoge et al., 2004). Concerning the high levels of noncombat-related stressors via adverse physical conditions, to our knowledge, this is the first investigation to study its effects with PTSD in special forces personnel returning from Afghanistan. We identified that members of the Portuguese SOF personnel appeared highly resilient in the face of harsh physical conditions of deployment, leading them experiencing appropriate levels of mental and physical readiness and well-being under the challenging circumstances of deployment. In a same line of research, preceding studies researchers have recognized opposite findings, highlighting that exposure to noncombat-related stressors were associated with PTSD caseness (Engelhard & Van Den Hout, 2007; King et al., 1995; Vogt, Pless, King, & King, 2005). During an operational deployment, members of SOF personnel are trained and expected to interact with the vicissitudes of a war-zone scenario and adapted physically and psychologically to them. Our data shows that SOF soldiers Table 4 Comparison of Combat Experiences and Adverse Physical Conditions in Posttraumatic Stress Disorder (PTSD) Symptoms Combat experiences Low and middle tertile Upper tertile Mann Whitney Z 1 9 experiences (n 67) experiences (n 34) M rank M rank PTSD symptoms Z 3.17 Adverse physical conditions Low and middle tertile Upper tertile 1 4 experiences (n 73) 5 8 experiences (n 37) M rank M rank PTSD symptoms Z 2.99 p.01.

8 COMBAT EXPOSURE AND PTSD 77 Table 5 Predictors of Posttraumatic Stress Disorder (PTSD) Symptoms, Unadjusted and Adjusted Odds Ratio (OR) With 95% Confidence Interval (CI) Exposure n (%) were physically and psychologically prepared to undertake the rehearsed demands of deployment (e.g., prolonged sleep deprivation, intense physical exertion) but not the unrehearsed ones (e.g., encountering civilian casualties, handling dead bodies, or being responsible for the killing of another human being). Thus, these data suggest it may be useful to prepare SOF soldiers for stressful noncombat-related experiences, which, through a stress inoculation process should ensure that their emotional physiological responses to the stressors would decline thereby making them toughened when confronted with similar stressful demands when deployed (Dienstbier, 1989; Thomas, Adler, Wittels, Enne, & Johannes, 2004). In addition, we also suggest that the repetition of a stressful task by using appropriate coping strategies may also lead them to handle more effectively in future with the noncombat-related events of deployment (Strentz & Auerbach, 1988). In regard to the training for combat experiences, training for extreme stressors is extremely specific and difficult to replicate, and the physical and psychological well-being of participants must be respected by its legal and ethical standards. We studied members of special forces personnel, as such one explanation for the low prevalence of PTSD could be the comparatively high levels of psychological hardiness. Portuguese SOFs selection is achieved through rigorous training, which also helps to prepare them for demanding high-risk operations; only hardy candidates complete training, and they may therefore be more resilient when faced with the stresses of deployment in Afghanistan. There is some evidence for increased hardiness in SOFs. OR (95% CI) Upper tertile PTSD symptoms Adjusted OR 1 (95% CI) a Adjusted OR 2 (95% CI) b Upper tertile combat experiences ( ) 2.79 ( ) 3.26 ( ) Low Middle tertile combat experiences Upper tertile adverse physical conditions ( ) 1.81 ( ) 1.68 ( ) Low Middle tertile adverse physical conditions Note. a Model 1 adjusted combat experiences for adverse physical conditions and adverse physical conditions for combat experiences. b Model 2 adjusted for combat experiences, adverse physical conditions, number of deployments, rank, marital status, and age. In an investigation conducted with U.S. Special Forces candidates, those with higher rates of psychological hardiness were more likely to complete training successfully than those with lower levels (Bartone et al., 2008). From another perspective, other studies conducted during harsh military training also suggest that SOF personnel are more prone to overcome intense psychological and physical stressors than their regular infantry counterparts, evidencing higher levels of tolerating stress, better trained capacities, and preparedness for such a stressor environment (Morgan, Wang et al., 2001). Despite this, and as suggested by Hing et al. (2012), caution is advised when generalizing singular stressful events experienced in a controller environment such as military training, with the real life and sometimes multiple threatening experiences of combat deployment. Low rates of PTSD were also reported by U.K. elite forces returning from Iraq. In that study, Royal Marines Commandos reported low rates of PTSD symptoms, and the authors suggested that this might be explained by high levels of unit cohesion, fitness, and preparedness for undertaking more hazardous military duties (Sundin, Jones, et al., 2010). In another study with members of the Sri Lanka Special Forces, issues such as unit cohesion and comradeship were also an important deterrent factor for mental health problems (Hanwella & De Silva, 2011). Besides that we could not establish a significant relationship between reporting unit-related problems and PTSD, a significant proportion of our sample reported high levels of unit satisfaction, which may have served as a buffer for the development or worsening of

9 78 OSÓRIO ET AL. PTSD (Mulligan et al., 2010). Another possible explanation could be that low rates of PTSD and partial PTSD may have been related to perceived stigma. A number of studies have assessed perceived stigma in military personnel and have reported that those with mental disorders had higher levels of concerns about possible stigmatization, including being seen as weak or not being trusted by peers than those than those without mental disorders (Britt, Greene- Shortridge, & Castro, 2007; Hoge et al., 2004; Langston et al., 2010). Of course, some of our respondents, given that they were members of a special force unit may have minimized their symptom reporting despite being reassured that their information would be completely confidential and anonymous. It is also possible that the length of time between their return from the deployment and their participation in the study may have contributed to their reduced PTSD rates. For instance, our study included personnel who have returned from deployment several years ago, and traumatic stress studies suggest that PTSD remission normally occurs within the first 3 years after deployment, evidencing a possible pattern remission of PTSD symptoms in our sample (Bonanno, 2005; Solomon, 1989). Those who completed a greater number of deployments were more likely to report higher levels of combat exposure, and yet more deployments were not associated with higher levels of PTSD. These findings are inconsistent with some previous traumatic stress research, which suggested that previous deployment was associated with poorer mental health outcomes (Adler, Huffman, Bliese, & Castro, 2005). Thus, caution is required when drawing conclusions from this study about the contribution of previous deployments to the development of PTSD. That being said, it may be that unlike regular infantry units, members from SOFs who have been deployed more often and have been exposed to more combat experiences may become habituated to the effects of deployment and therefore did not experience more mental health problems as a result of cumulative deployment. The literature on the general as opposed to traumatic stress suggests that when individuals learn how to deal effectively with a particular stressor event, they became more resilient and improve their response to a subsequent similar stressor (Adler et al., 2005). It could also be that previous experiences of deployment may also help to protect soldiers from the future stress of deployment through the acquisition of adaptive thinking and appropriate coping strategies (Adler et al., 2005; Solomon, 1993). There are several study limitations that should be taken into account when interpreting our results. First, the cross-sectional selfreported design obtained only in a postdeployment phase limits our ability to make causal inferences about the effects of combat- and noncombat-related stressors on the mental health of deployed personnel. Second, the sample was not randomly selected, and the snowball sampling method may not be fully representative of the target population as it is likely to have introduced sample bias. Third, the study findings were only based on the responses of military members from SOFs, and the results cannot be generalized to the larger Portuguese army population. Fourth, this study relied on selfreported measures and was not derived from structured interviews. Also, for some participants, there was a long pause between returning from deployment and completing the survey, therefore recall bias may be an issue as may socially desirable responses from participants. Fifth, in total, our sample only included 113 participants from an assumed estimated population of 500 SOFs Commandos deployed in Afghanistan between 2005 and For our sample to be fully representative of the total amount of Portuguese SOFs Commandos deployed in theater, our research should have included a minimum number of 272 participants to achieve a 95% confidence level. Last, the response rate in our research was only 48.7%, which again suggests that response bias is present. This is important, because several studies have evaluated participants who refused to collaborate in traumatic stress investigations and found that they reported more mental health problems, compared with those who participated (Weisaeth, 1989). Thus, these systematic differences in characteristics between those who were interested in participating in the study from those who were not (which included mainly healthy participants) may have influenced the significant low prevalence rate of PTSD in our study (Li & Sung, 1999; Shah, 2009).

10 COMBAT EXPOSURE AND PTSD 79 Conclusion Although our findings suggest that PTSD in Portuguese Special Forces is low in spite of the exposure to several combat and noncombat related stressors, those soldiers who reported higher levels of combat exposure were significantly more likely to experience PTSD. Our findings also highlighted that, in this group of personnel, more frequent deployments were not related with PTSD. It therefore seems that SOF personnel appear especially resilient, but not wholly resistant, to the challenging experiences of deployment. In particular we suggest that SOF personnel appear to cope well with the challenges to which they have been exposed, often repeatedly, during their arduous training but not so well with those with which they have not been trained to deal. Thus, it might be that one protective aspect of being an SOF soldier could be the intense training they receive; it might be that if their regular counterparts received the same level of training they too would endorse similarly low rates of mental health problems. The extent of PTSD symptoms in members in SOF personnel who are returning from operational deployments is currently scarce; the few studies that have evaluated this elite group of soldiers do not provide a coherent view about how common PTSD is in this group. More work in needed to investigate both what the true extent of mental health problems is in this group and how mental health conditions could negatively impact the soldiers well-being, including potential risk factors and including their combat effectiveness. Despite the study limitations, these findings with members of the Portuguese SOF personnel have implications for how health care delivery and mental health support, in general, should be considered within the Portuguese Army, especially for military members who are returning from operational deployments. References Adler, A. B., Huffman, A. H., Bliese, P. D., & Castro, C. A. (2005). The impact of deployment length and experience on the well-being of male and female soldiers. Journal of Occupational Health Psychology, 10, American Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed., text rev.). Washington, DC: Author. Bartolomeu, C. (2008). Afeganistão - Mais uma missão cumprida [Afghanistan - One more accomplished mission]. Jornal do Exército, 576, Bartone, P. T., Roland, R. R., Picano, J. J., & Williams, T. (2008). Psychological hardiness predicts success in US Army Special Forces candidates. International Journal of Selection and Assessment, 16, Bonanno, G. A. (2005). Resilience in the face of potential trauma. Current Directions in Psychological Science, 14, Booth-Kewley, S., Larson, G. E., Highfill-McRoy, R. M., Garland, C. F., & Gaskin, T. A. (2010). Correlates of posttraumatic stress disorder symptoms in Marines back from war. Journal of Traumatic Stress, 23, Britt, T. W., Greene-Shortridge, T. M., & Castro, C. A. (2007). The stigma of mental health problems in the military. Military Medicine, 172, Castro, C. A., Adler, A. B., & Huffman, A. H. (1999). Psychological screening of U.S. peacekeepers in Bosnia. In Proceedings of the 41st Annual Conference of the International Military Testing Association, Monterey, California (pp ). Retrieved from /99IMTAproceedings.pdf Chemtob, C. M., Bauer, G. B., Neller, G., Hamada, R., Glisson, C., & Stevens, V. (1990). Posttraumatic stress disorder among special forces Vietnam veterans. Military Medicine, 155, Dienstbier, R. A. (1989). Arousal and physiological toughness implications for mental and physical health. Psychological Review, 96, Engelhard, I. M., & Van Den Hout, M. A. (2007). Preexisting neuroticism, subjective stressor severity, and post-traumatic stress in soldiers deployed in Iraq. Canadian Journal of Psychiatry, 52, Espinoza, J. M. (2010). Posttraumatic stress disorder and the perceived consequences of seeking therapy among U.S. Army special forces operators exposed to combat. Journal of Psychological Issues in Organizational Culture, 1, Fear, N. T., Jones, M., Murphy, D., Hull, L., Iversen, A. C., Coker, B.,... Wessely, S. (2010, May 22). What are the consequences of deployment to Iraq and Afghanistan on the mental health of the UK armed forces? A cohort study. The Lancet, 375, Hanwella, R., & De Silva, V. (2012). Mental health of special forces personnel deployed in battle. Social Psychiatry and Psychiatric Epidemiology, 47, Hing, M., Cabrera, J., Barstow, C., & Forsten, R. (2012). Special operations forces and incidence of

11 80 OSÓRIO ET AL. post-traumatic stress disorder symptoms. Journal of Special Operations Medicine, 12, Hoge, C. W., Castro, C. A., Messer, S. C., McGurk, D., Cotting, D. I., & Koffman, R. L. (2004). Combat duty in Iraq and Afghanistan, mental health problems, and barriers to care. New England Journal of Medicine, 351, Iversen, A. C., Fear, N. T., Ehlers, A., Hacker Hughes, J., Hull, L., Earnshaw, M.,...Hotopf, M. (2008). Risk factors for post-traumatic stress disorder among UK Armed Forces personnel. Psychological Medicine, 38, Jakupcak, M., Conybeare, D., Phelps, L., Hunt, S., Holmes, H. A., Felker, B.,... McFall, M. E. (2007). Anger, hostility, and aggression among Iraq and Afghanistan War veterans reporting PTSD and subthreshold PTSD. Journal of Traumatic Stress, 20, King, D. W., King, L. A., Gudanowski, D. M., & Vreven, D. L. (1995). Alternative representations of war zone stressors: Relationships to posttraumatic stress disorder in male and female Vietnam veterans. Journal of Abnormal Psychology, 104, Kok, B. C., Herrell, R. K., Thomas, J. L., & Hoge, C. W. (2012). Posttraumatic stress disorder associated with combat service in Iraq or Afghanistan: Reconciling prevalence differences between studies. The Journal of Nervous and Mental Disease, 200, Kulka, R. A., Schlenger, W. E., Fairbank, J. A., Hough, R. L., Jordan, B. K., & Weiss, D. S. (1990). Trauma and the Vietnam War generation: Report of findings from the National Vietnam Veterans Readjustment Study. New York, NY: Brunner/Mazel. Langston, V., Greenberg, N., Fear, N., Iversen, A., French, C., & Wessely, S. (2010). Stigma and mental health in the Royal Navy: A mixed methods paper. Journal of Mental Health, 19, Li, C. Y., & Sung, F. C. (1999). A review of the healthy worker effect in occupational epidemiology. Occupational Medicine, 49, Litz, B. T., King, L. A., King, D. W., Orsillo, S. M., & Friedman, M. J. (1997). Warriors as peacekeepers: Features of the Somalia experience and PTSD. Journal of Consulting and Clinical Psychology, 65, Maia, A., McIntyre, T., Pereira, M. G., & Ribeiro, E. (2011). War exposure and post-traumatic stress as predictors of Portuguese colonial war veterans physical health. Anxiety, Stress, and Coping, 24, McIntyre, T., & Ventura, M. (1996). Escala de avaliação da resposta aos acontecimentos traumáticos [Response to Traumatic Event Scale]. In L. S. Almeida, S. Araújo, M. M. Gonçalves, C. Machado, & M. R. Simões (Eds.), Avaliação Psicológica: Formas e Contextos Volume IV (pp ). Braga, Portugal: APPORT: Universidade do Minho. Joint Mental Health Advisory Team 7. (2011). Joint Mental Health Advisory Team (J-MHAT) Operation Enduring Freedom 2010 Afghanistan. Retrieved from reports/mhat/mhat_vii/j_mhat_7.pdf Morgan, C. A., III, Hazlett, G., Wang, S., Richardson, E. G., Jr., Schnurr, P., & Southwick, S. M. (2001). Symptoms of dissociation in humans experiencing acute, uncontrollable stress: A prospective investigation. American Journal of Psychiatry, 158, Morgan, C. A., III, Wang, S., Rasmusson, A., Hazlett, G., Anderson, G., & Charney, D. S. (2001). Relationship among plasma cortisol, catecholamines, neuropeptide Y, and human performance during exposure to uncontrollable stress. Psychosomatic Medicine, 63, Morgan, C. A., III, Wang, S., Southwick, S. M., Rasmusson, A., Hazlett, G., Hauger, R. L., & Charney, D. S. (2000). Plasma neuropeptide-y concentrations in humans exposed to military survival training. Biological Psychiatry, 47, Mulligan, K., Jones, N., Woodhead, C., Davies, M., Wessely, S., & Greenberg, N. (2010). Mental health of UK military personnel while on deployment in Iraq. British Journal of Psychiatry, 197, Neville, L., & Bujeiro, R. (2008). Special operations forces in Afghanistan. Oxford, England: Osprey Publishing. Pietrzak, R. H., Goldstein, M. B., Malley, J. C., Johnson, D. C., & Southwick, S. M. (2009). Subsyndromal posttraumatic stress disorder is associated with health and psychosocial difficulties in veterans of Operations Enduring Freedom and Iraqi Freedom. Depression and Anxiety, 26, Richardson, R. D., Engel, C. C., Hunt, S. C., McKnight, K., & McFall, M. (2002). Are veterans seeking Veterans Affairs Primary Care as healthy as those seeking Department of Defense Primary Care? A look at Gulf War Veterans symptoms and functional status. Psychosomatic Medicine, 64, Schnurr, P. P., Ford, J. D., Friedman, M. J., Green, B. L., Dain, B. J., & Sengupta, A. (2000). Predictors and outcomes of posttraumatic stress disorder in World War II veterans exposed to mustard gas. Journal of Consulting and Clinical Psychology, 68, Shah, D. (2009). Healthy worker effect phenomenon. Indian Journal of Occupational and Environmental Medicine, 13,

12 COMBAT EXPOSURE AND PTSD 81 Shalev, A., Bleich, A., & Ursano, R. J. (1990). Posttraumatic stress disorder: Somatic comorbidity and effort tolerance. Psychosomatics, 31, Smith, T. C., Ryan, M. A., Wingard, D. L., Slymen, D. J., Sallis, J. F., Kritz-Silverstein, D., & Millennium Cohort Study Team. (2008). New onset and persistent symptoms of post-traumatic stress disorder self reported after deployment and combat exposures: Prospective population based US military cohort study. British Medical Journal, 336, Solomon, Z. (1989). Psychological sequelae of war: A 3-year prospective study of Israeli combat stress reaction casualties. The Journal of Nervous and Mental Disease, 177, Solomon, Z. (1993). Combat stress reaction: The enduring toll of war. New York, NY: Plenum Press. Strentz, T., & Auerbach, S. M. (1988). Adjustment to the stress of simulated captivity: Effects of emotion-focused versus problem-focused preparation on hostages differing in locus of control. Journal of Personality and Social Psychology, 55, Sundin, J., Fear, N. T., Iversen, A., Rona, R. J., & Wessely, S. (2010). PTSD after deployment to Iraq: Conflicting rates, conflicting claims. Psychological Medicine, 40, Sundin, J., Jones, N., Greenberg, N., Rona, R. J., Hotopf, M., Wessely, S., & Fear, N. T. (2010). Mental health among commando, airborne and other UK infantry personnel. Occupational Medicine, 60, Thomas, J. L., Adler, A. B., Wittels, P., Enne, R., & Johannes, B. (2004). Comparing elite soldiers perceptions of psychological and physical demands during military training. Military Medicine, 169, Vogt, D. S., Pless, A. P., King, L. A., & King, D. W. (2005). Deployment stressors, gender, and mental health outcomes among Gulf War I veterans. Journal of Traumatic Stress, 18, Weisaeth, L. (1989). Importance of high response rates in traumatic stress research. Acta Psychiatrica Scandinavica. Supplementum, 355,