The primary objective of this study was to replicate, in a female sample of rape survivors with chronic PTSD, prior findings of personality-based internalizing and externalizing subtypes of posttraumatic psychopathology observed in two studies of male combat veterans (Miller et al., 2003
). The assessment featured the SNAP, a factor-analytically derived, self-report inventory that measures trait dimensions and clinical syndromes in the domain of personality disorders (Clark, 1996
). The three SNAP temperament scales (Positive Temperament, Negative Temperament, and Disinhibition) were submitted to a cluster analysis that partitioned the sample into a lower pathology or “simple PTSD” cluster, defined by normal-range temperament scores and relatively low levels of symptoms across multiple indices of psychopathology, and two more pathological or “complex PTSD” clusters that differed on variables related to the externalization versus internalization of distress.
The externalizing cluster was defined by high scores on the Disinhibition and Negative Temperament scales. Individuals in this cluster described themselves as prone to act impulsively with little regard for the consequences of their actions (i.e., high disinhibition), as well as easily upset, chronically nervous, stressed, and worried (i.e., high negative temperament). On the SNAP trait and personality disorder scales they described themselves as more exhibitionistic, manipulative, and unconventional than individuals in either of the other two clusters. They also endorsed more features of borderline, antisocial, narcissistic, and histrionic personality disorder. On the TSI, externalizers produced the highest scores of the three groups on the Dysfunctional Sexual Behaviors scale (measuring the inappropriate use of sex to accomplish nonsexual goals and risky or self-destructive sexual behavior) and the Tension Reduction Behavior scale (measuring efforts to reduce distress through maladaptive means such as self-mutilation, angry outbursts, and suicide threats). SCID interviews showed externalizers to be the most likely of the three groups to have a history of substance dependence.
These findings suggest that a substantial subset of women with chronic PTSD exhibit many of the core personality features and clinical correlates observed previously in externalizing male veterans with PTSD (Miller et al., 2003
). It is noteworthy, however, that the proportion
of cases assigned to the externalizing cluster in this study was somewhat smaller than that observed in Miller et al.’s prior studies. Twenty-one and 45% of women with PTSD in this sample were assigned to the externalizing and internalizing clusters, respectively. By comparison, collapsing across the two prior studies of male combat veterans (N
=808), Miller et al. observed that 27% and 42% of cases were assigned to the externalizing and internalizing groups, respectively, suggesting that the proportion of externalizers in this female sample was somewhat smaller than that observed in males.1
This observation is in line with prior research suggesting that women may be less likely than men to develop externalizing disorders (e.g., Kessler et al., 1997
; Kessler, McGonagle, Swartz, Blazer, & Nelson, 1993
; Rende & Plomin, 1992
) and evidence that female adolescents exposed to trauma are more likely to exhibit internalizing symptoms whereas males are more likely to evidence externalizing ones (Kirz, Drescher, Klein, Gusman, & Schwartz, 2001
; Schwab-Stone et al., 1999
). Otherwise, the proportion of cases assigned to the three clusters in this study was consistent with results of Miller et al.’s two prior studies, and overall, results suggest that male and female externalizers with PTSD share many of the same characteristics, i.e., marked difficulties in the domains of impulsivity, anger, aggression, antisociality, and substance abuse.
In contrast to their externalizing counterparts, internalizers were defined by low scores on the SNAP Positive Temperament scale and high scores on Negative Temperament. Individuals in this cluster described themselves as unenthusiastic, uninspired, easily fatigued, lacking interests, (i.e., low positive temperament), and like externalizers, prone to experiencing frequent and intense negative emotions (i.e., high negative temperament). The internalizers’ SNAP Trait scale profile suggests that they tend to have few friends, are aloof and distant from others, and prefer to spend time alone (high detachment). In contrast with the exhibitionistic and narcissistic tendencies of the externalizers, they tend to be self-effacing, humble, and do not feel particularly special, admirable, or talented (low entitlement). Internalizers also achieved the highest scores of the three groups on the Schizoid and Avoidant Personality Disorder scales, suggesting a restricted range of emotions in interpersonal settings, social inhibition, feelings of inadequacy, and hypersensitivity to negative evaluation. As in Miller et al.’s (2003
) two prior studies, internalizers showed the highest rates of comorbid major depression of the three groups.
Measures of shame (ISS), physical complaints (PILL) and alexithymia (TAS) expanded upon these characterizations, offering new insights into the psychopathology of the internalizer. Internalizers produced the highest scores of the three clusters on the ISS, an inventory assessing shameful feelings that have been internalized as part of one’s identity and are reflected in feelings of inferiority, inadequacy, or deficiency (Cook, 1987
). This finding may reflect an essential aspect of the psychopathology of the internalizer: the tendency to incorporate into his/her identity shameful aspects of the traumatic experience. Internalizers also produced significantly higher scores on the TAS and PILL than individuals in the simple PTSD group, suggesting a relative deficit in the capacity to identify and describe emotions and a greater frequency of physical complaints. These findings are consistent with other research suggesting a link between alexithymia and somatization (Cohen, Auld, & Brooker, 1994
; Lumley & Norman, 1996
) and evidence that these characteristics tend to covary with PTSD severity (Monson et al., 2004
; Zlotnick, Mattia, & Zimmerman, 2001
), the internalizing disorders (Achenbach & Rescorla, 2003
; Marchesi, Brusamonti, & Maggini, 2000
), and the primary personality substrate of these disorders, negative emotionality (Watson & Pennebaker, 1989
Along the same lines, internalizers endorsed significantly more severe hyperarousal symptoms than the other two groups and received significantly higher PTSD severity scores on the CAPS than the simple PTSD group with a trend in the same direction observed in comparison to the externalizers. A tendency for internalizers to exhibit more severe PTSD symptoms was also observed in the second of the two prior studies by Miller et al. (2004)
, who suggested that it may reflect the greater construct overlap between the PTSD syndrome, as defined by DSM-IV
, and the psychopathology of the internalizing subtype. This reasoning was based on findings of comorbidity research suggesting that PTSD tends to covary primarily with the “anxious-misery” disorders (i.e., major depression, dysthymia, and generalized anxiety disorder; Cox, Clara, & Enns, 2002
) that load together on a latent internalizing dimension of psychopathology (Krueger et al., 1998
; Krueger et al., 2002
) and factor analyses showing that many of the symptoms of PTSD load on a broad dysphoria factor shared by these disorders (Simms, Watson, & Doebbeling, 2002
IMPLICATIONS FOR THE CONCEPTUALIZATION OF COMPLEX PTSD
The three groups observed in this and Miller et al.’s (2003
) prior studies may inform the understanding of the heterogeneous array of symptoms termed complex PTSD and help to define their relation to simple PTSD. Herman (1992)
conceptualized complex PTSD as involving (a) symptoms that are more extensive and severe than in simple PTSD, (b) marked personality disturbance, and (c) heightened vulnerability to repeated harm. The measures selected for analysis in this study were chosen with the aim of capturing the essential aspects of the complex PTSD construct including dissociation, impaired self-concept, physical complaints, dysfunctional sexual behavior, internalized shame, and anger, as well as measures of personality disturbance indexed by the SNAP. The finding of a lower pathology PTSD cluster defined by normal range scores on the SNAP contrasted with two higher pathology PTSD subgroups defined by marked personality disturbance and severe and diverse symptomatology is consistent with Herman’s conceptualization of the distinction between simple and complex PTSD and prior descriptive research (e.g., Ford, 1999
; Zlotnick et al., 1996
). Internalizers and externalizers showed higher scores than the simple PTSD group on an array of scales measuring constructs central to the concept of complex PTSD, including indices of impaired interpersonal functioning, self-harm behavior, physical complaints, identity disturbance, dysfunctional sexual behavior, internalized shame, and anger. However, the findings also underscore the heterogeneous presentations of individuals with complex PTSD and suggest the presence of clinically meaningful subtypes of the disorder. They also suggest that the SNAP may be useful for differentiating simple from complex forms of PTSD and internalizing and externalizing variants of the latter.
Contrary to prediction, there were no significant differences between groups on measures of trauma history. We had hypothesized, on the basis of Herman’s (1992)
conceptualization and evidence for the role of early developmental trauma and repeated traumatization in the etiology of the complex PTSD (Ford, 1999
; McLean & Gallop, 2003
; Resick et al., 2003
; Roth et al., 1997
), that internalizers and externalizers would report more extensive trauma histories and be more likely to endorse histories of childhood sexual abuse than those in the simple PTSD group. This was a severely and repeatedly traumatized sample of rape survivors who reported high rates of childhood physical and sexual abuse as well as adult criminal victimization. As a result, we found high but rather restricted ranges of scores on measures of trauma exposure. It may be that the hypothesized association between early abuse and complex PTSD is more likely to be observed in samples with greater variability in the severity and type of trauma histories reported. That said, this is not the first study of this type to find no differences between individuals with and without complex PTSD on measures of childhood trauma (cf. Allen et al., 1999
) and it is also possible that factors other than the nature and severity of the trauma, including pre-trauma vulnerability toward internalizing and externalizing psychopathology (Miller, 2003
), may play important roles in the etiology of complex PTSD.
STUDY LIMITATIONS AND DIRECTIONS FOR FUTURE RESEARCH
The present findings should be evaluated in the context of the study’s strengths and limitations. First, the fact that the sample was comprised exclusively of women with diagnoses of PTSD rendered it impossible for us to evaluate whether similar subtypes would be evident in individuals with primary diagnoses other than PTSD. Psychiatric epidemiology studies suggest that similar solutions would be found in some, but not all, mental disorders with the determining factor being the degree of heterogeneity and breadth of comorbidity associated with the index disorder. Of the anxiety disorders, PTSD shows the most severe and diverse pattern of diagnostic comorbidity (Brown, Campbell, Lehman, Grisham, & Mancill, 2001
), with frequently co-occurring conditions ranging from those of the internalizing spectrum, including the unipolar mood and anxiety disorders, to the externalizing spectrum, such as antisociality and substance abuse. Certain other disorders show similar patterns of comorbidity spanning these spectra. For example, there is a strong similarity between the internalizing and externalizing subtypes found in this work and Cloninger’s (1987)
Type I and Type II alcoholics. The former (internalizing type) is characterized by the use of alcohol in association with heightened negative affectivity to avoid, dampen, or escape those states, whereas the latter (externalizing type) reflects alcohol problems stemming from propensities toward sensation-seeking, risky and/or uninhibited behavior.
On the other hand, disorders with a narrower range of comorbidity—and perhaps more distinct and circumscribed phenotypes—rarely co-occur. For example, Kessler et al. (2005)
recently reported that the internalizing spectrum disorders OCD and separation anxiety disorder were negatively correlated with the externalizing syndromes drug dependence and conduct disorder. Generalizing from this, one would not expect to find large numbers of externalizers among samples composed of individuals with protoypic internalizing diagnoses, especially those related to pathological fear, or vise versa (e.g., antisocial personality disorder is not a problem commonly found among individuals with specific phobia). In sum, while we can not, and would not, claim this typology to be unique to posttraumatic psychopathology, we do believe that our data showing the presence of temperament-based internalizing and externalizing subtypes of complex posttraumatic psychopathology and their distinctions from simple PTSD offers a useful heuristic for organizing and conceptualizing the broad heterogeneity in clinical presentations of trauma survivors.
A second major limitation of the study was that etiological inferences about the extent to which these subtypes reflect the influence of premorbid personality are limited by the cross-sectional methods that were employed. Evidence for the longitudinal stability of personality traits in other research (e.g., Costa & McCrae, 1977
; Watson & Walker, 1996
) and indications of greater pre-military delinquency in the externalizing group in our prior studies (Miller et al., 2003
; Miller et al., 2004
) raise the possibility that these subtypes reflect the influence of premorbid traits on the expression of posttraumatic symptomatology. However, this does not exclude the additional possibility that personality traits may be altered as a consequence of the development of PTSD. The latter is based on two basic tenets: (a) adaptive personality functioning involves the inhibition of pathological behavioral tendencies, including dispositions toward internalizing and externalizing psychopathology, and (b) PTSD compromises these self-regulatory processes resulting in the accentuation of pathogenic traits relative to premorbid levels (cf. Miller, 2003
; Miller, Vogt, Mozley, Kaloupek, & Keane, 2006
). These propositions are consistent with the observations of prior theorists who conjectured that traumatic events operate on individuals by accentuating pathological tendencies evident in their premorbid functioning (Allport, Bruner, & Jandorf, 1941
Future studies should examine these propositions using prospective longitudinal designs incorporating the assessment of personality and psychopathology pre- and posttrauma exposure and/or behavioral genetics designs that would permit examination of the degree of similarity among identical twins discordant for trauma exposure on measures of personality and psychiatric symptomatology. It would also be useful in future work to examine the influence of these subtypes on the course of symptomatology using longitudinal analyses, such as growth curve analysis, which permit the examination of individual trajectories representing change over time. On a related note, the study would also have benefited from the inclusion of data other than self-reports and interviews; for example, laboratory measures, biological indices, or measures of family history might lend support to the validity of the internalizing/externalizing typology or shed additional light on the etiological processes involved.
A third limitation was that, although a primary objective of this study was to examine the relevance of the internalizing/externalizing typology to the understanding of complex PTSD, the assessment did not include a measure specifically designed to assess complex PTSD or DESNOS. Instead, we relied upon a collection of measures that are conceptually related to, and provide good coverage of, the construct as it has been defined by other theorists, but have not yet been validated as such. Fourth, the sample sizes for individual clusters were modest and some important group differences failed to achieve statistical significance after controlling for family-wise error.
Regarding its strengths, this study represents a novel effort to clarify the psychometric distinction between simple and complex PTSD, and it provides new insight into the structure of post-traumatic psychopathology in the domain of personality disorders. It also provided an important replication of the 3-group typology previously observed only in male combat veterans (Miller et al., 2003
; Miller et al., 2004
). Moreover, the close correspondence between the subtypes identified in this work and three major personality “types” identified by developmental psychologists (i.e., resilient, overcontrolled, and undercontrolled; Asendorpf & van Aken, 1999
; Hart, Hofmann, Edelstein, & Keller, 1997
; Robins, John, Caspi, Moffitt, & Stouthamer-Loeber, 1996
) lends support to the validity of this typology and its relation to a fundamental structure of individual differences. In future research, it may be useful to examine the relevance of this typology to the understanding of symptom heterogeneity in related conditions such as borderline personality disorder, which is characterized by both extreme externalizing (e.g., self-mutilation, shoplifting, displays of anger, combative and antagonistic interpersonal relationships) and internalizing behavior (e.g., major depression, anxiety, poor self-image, interpersonal withdrawal; APA, 1994
). Finally, identification of valid subtypes of posttraumatic psychopathology may facilitate the study of the underlying genetic or neurobiological mechanisms, advance the understanding of diagnostic co-occurrence, and contribute to the development and evaluation of treatments that more effectively address the considerable heterogeneity in presentation among individuals with PTSD.