Abnormal Personality and the Mood and Anxiety

Abnormal personality and the mood and anxiety

disorders: Implications for structural models

of anxiety and depression

Wakiza Gamez a,*, David Watson a, Bradley N. Doebbeling b

a Department of Psychology, University of Iowa, E11 Seashore Hall, Iowa City, IA 52242, United Statesb Department of Internal Medicine, Indiana University School of Medicine, Regenstrief Institute,

and Indianapolis Roudebush Veterans’ Affairs Medical Center, Indianapolis, IN, United States

Received 15 March 2006; received in revised form 6 July 2006; accepted 1 August 2006

Abstract

Substantial overlap exists between the mood and anxiety disorders. Previous research has suggested that

their comorbidity can be explained by a shared factor (negative emotionality), but that they may also be

distinguished by other unique components. The current study explicated these relations using an abnormal

personality framework. Current diagnoses of major depression and several anxiety disorders were assessed

in 563 Gulf War veterans. Participants also completed the schedule for nonadaptive and adaptive personality

(SNAP) to determine how these disorders relate to abnormal personality traits. Analyses of individual

diagnoses indicated that depression, generalized anxiety disorder (GAD), and post-traumatic stress disorder

(PTSD) were more strongly related to personality than were other anxiety disorders. The Self-Harm Scale

distinguished major depression from all other disorders, highlighting its significance for future structural

models. Our results add to a growing body of evidence suggesting that GAD and PTSD have more in

common with major depression than with their anxiety disorder counterparts.

# 2006 Elsevier Ltd. All rights reserved.

Keywords: SNAP; Structural model; Personality; Depression and anxiety

1. Introduction

The Diagnostic and Statistical Manual of Mental Disorders (4th ed.) (American Psychiatric

Association, 1994) establishes a basic distinction between the mood disorders and the anxiety

disorders. It is clear, however, that substantial overlap/comorbidity exists between these two

Journal of Anxiety Disorders 21 (2007) 526–539

* Corresponding author. Tel.: +1 319 335 2406; fax: +1 319 335 0191.

E-mail address: [email protected] (W. Gamez).

0887-6185/$ – see front matter # 2006 Elsevier Ltd. All rights reserved.

doi:10.1016/j.janxdis.2006.08.003

mailto:[email protected]

http://dx.doi.org/10.1016/j.janxdis.2006.08.003

diagnostic classes (Brown & Barlow, 1992; Brown, Campbell, Lehman, Grisham, & Mancill,

2001). In response to this evidence, Mineka, Watson, and Clark (1998) proposed the integrative

hierarchical model wherein each syndrome contains both a common and a unique component. The

shared component represents broad individual differences in general distress and negative

emotionality. In addition, each disorder also includes a unique component that differentiates it from

all of the others. Specifically, low positive emotionality is posited to be specific to depression (and

possibly social phobia), whereas autonomic arousal is characteristic of panic disorder.

Despite these advances, much research still needs to be done to clarify both the links between

disorders and the specific dimensions that differentiate them. In the current study, we investigate

these issues by examining how the mood and anxiety disorders relate to a broad range of

personality traits, including this shared component of negative emotionality.

1.1. Models of personality

This paper will focus primarily on the Big Three model of personality. This model consists of the

higher order dimensions of Neuroticism/Negative Emotionality, Extraversion/Positive Emotion-

ality, and Disinhibition (or Psychoticism) versus Constraint (Clark & Watson, 1999; Eysenck &

Eysenck, 1991; Tellegen, 1982), and has been found to encompass normal and abnormal (i.e.,

personality disorder) traits (Clark, 1993). We should also note that this Big Three scheme has been

linked both conceptually and empirically to the prominent Big Five model (Costa & McCrae,

1992a; Goldberg, 1993), and it is clear that they define very similar structures (see Clark & Watson,

1999; Costa & McCrae, 1992b; Draycott & Kline, 1995; Watson, Clark, & Harkness, 1994). The

Big Five model includes the general traits of Neuroticism, Extraversion, Openness, Agreeableness,

and Conscientiousness. Neuroticism and Extraversion map directly onto the first two dimensions of

the Big Three model, whereas Agreeableness and Conscientiousness both are related primarily to

the Disinhibition/Constraint factor (with Conscientiousness being the more strongly related of the

two; see Clark, Simms, Wu, & Casillas, in press; Clark & Watson, 1999; Draycott & Kline, 1995;

Markon, Krueger, & Watson, 2005; Watson et al., 1994).

1.2. Previous research on the Big Three

In the literature examining relations between personality and the mood and anxiety disorders,

the most robust finding is that levels of Neuroticism/Negative Emotionality are elevated across a

broad range of syndromes (Bienvenu et al., 2001; Clark, Watson, & Mineka, 1994; Krueger,

Caspi, Moffitt, Silva, & McGee, 1996; Trull & Sher, 1994; Widiger & Trull, 1992). However,

although these disorders all share this common link with Neuroticism/Negative Emotionality,

some syndromes may be distinguished by the relative amount of the trait that they evidence

(Mineka et al., 1998). For instance, Trull and Sher (1994) reported particularly high levels of

Neuroticism in those with major depression and post-traumatic stress disorder. In contrast, those

with specific phobia were found to have relatively lower elevations on the Neuroticism

dimension. More generally, major depression, dysthymia, and generalized anxiety disorder are

characterized by a particularly large negative affective component (Mineka et al., 1998).

In contrast to Neuroticism, levels of Extraversion/Positive Emotionality appear to be

somewhat lower than normal in all of the unipolar mood and anxiety disorders (Widiger & Trull,

1992). As with Neuroticism, however, certain disorders evidence particularly strong links to this

trait. More specifically, low Extraversion has been found to be associated particularly with major

depression and social phobia (Brown, Chorpita, & Barlow, 1998; Clark & Watson, 1991; Clark

W. Gamez et al. / Journal of Anxiety Disorders 21 (2007) 526–539 527

et al., 1994; Trull & Sher, 1994; Watson, Clark, & Carey, 1988). In addition, some studies have

found agoraphobia (Bienvenu et al., 2001; Trull & Sher, 1994) to be characterized by low

Extraversion.

Finally, the available data do not establish any strong, consistent associations between

Disinhibition/Constraint and the mood and anxiety disorders (Bienvenu et al., 2001; Krueger

et al., 1996). Generally speaking, this trait shows much stronger links to the ‘‘externalizing

disorders’’ (such as substance abuse/dependence and antisocial personality) than to depression

and anxiety (Krueger, McGue, & Iacono, 2001). However, low conscientiousness was found to be

associated with major depression in one study (Trull & Sher, 1994).

1.3. Overview of the current study

The current study extends the existing literature by providing a more comprehensive analysis

of the associations between personality and the mood and anxiety disorders. It does so by

examining relations between a broad range of diagnoses and both higher order and lower order

personality traits. The study had three basic goals. First, previous work has clearly established

that Neuroticism/Negative Emotionality and Extraversion/Positive Emotionality both are

significantly linked to the mood and anxiety disorders. It currently is not clear, however, whether

other traits also have significant, incremental links to these disorders. We investigated this issue

by examining whether other trait scales provide significant predictive power beyond that

attributable to these higher order dimensions.

Second, we sought to replicate and extend previous work suggesting that there are important

quantitative variations in these relations, such that Neuroticism/Negative Emotionality is more

strongly related to some disorders (especially major depression, generalized anxiety, and post-

traumatic stress disorder) than to others (e.g., specific phobia).

To date, few studies in this area have compared more than two mood/anxiety disorders

simultaneously. In order to allow for direct comparisons across syndromes, we assessed a broad

range of mood and anxiety disorder diagnoses (major depression, generalized anxiety disorder,

social phobia, panic disorder, agoraphobia, specific phobia, and post-traumatic stress disorder).

Because of research demonstrating retrospective recall biases (Fredrickson & Kahneman, 1993;

Wright, 1993) and the questionable stability of lifetime diagnoses (Nelson & Rice, 1997;

Vandiver & Sher, 1991), we examined current diagnoses in our analyses.

The schedule for nonadaptive and adaptive personality (SNAP; Clark, 1993) was used to

assess personality in our study. The SNAP was developed originally to measure the basic

personality traits underlying the broad domain of personality disorders. It provides scales

assessing the Big Three traits, as well as 12 relatively distinct lower order scales; this

differentiated structure offers an enhanced opportunity to discriminate between specific

diagnoses. To date, few studies have examined relations between multiple mood/anxiety

diagnoses and lower order personality traits (Bienvenu et al., 2001; Rector, Hood, Richter, &

Bagby, 2002). Finally, it should be noted that the SNAP scales have not been extensively

examined in relation to a broad range of specific Axis I syndromes (see Clark, Vittengl, Kraft, &

Jarrett, 2003); consequently, our data represent a noteworthy extension to the existing literature.

We examined whether the SNAP scales were differentially related to individual diagnoses. We

derived several hypotheses from our earlier review of the literature. Specifically, we hypothesized

that the SNAP Negative Temperament Scale would be significantly associated with all of the

assessed diagnoses, but that its strongest links would be to major depression, generalized anxiety

disorder, and post-traumatic stress disorder. In contrast, specific phobia should be more weakly

W. Gamez et al. / Journal of Anxiety Disorders 21 (2007) 526–539528

related to Negative Temperament relative to the other disorders. In addition, we predicted that the

SNAP Positive Temperament Scale would be negatively related to both major depression and

social phobia (e.g., Brown et al., 1998; Clark et al., 1994). Because the limited existing evidence

has failed to establish any strong and consistent associations between the mood and anxiety

disorders and Disinhibition/Constraint, we made no formal predictions regarding this trait.

Finally, because prior studies have not compared individual SNAP scales across Axis I diagnoses,

no predictions were made regarding specific lower order trait scales.

2. Method

2.1. Participants

Participants originally completed a phone interview that was designed to assess different

health-related characteristics among military veterans who served during the Gulf War (Time 1,

conducted between 1995 and 1996). Participants were considered eligible if they: (1) served as

active duty or activated National Guard or U.S. Army Reserve during the Gulf War between

August 2, 1990 and July 31, 1991 and (2) listed Iowa as their state of residence at the time of

enlistment. A stratified random sample was drawn from each of four domains: deployed active

duty or National Guard/Reserve and non-deployed active duty or National Guard/Reserve.

Within each domain, further stratifying was done (on the basis of age, sex, race, military branch,

and rank), which resulted in a total of 64 strata. Samples from each stratum were drawn

proportionally, and oversampling of small strata was performed. Of the 4886 who were sampled

via this procedure, 3695 (75.6%) participated in the structured telephone interview. Details of the

original study methodology can be found elsewhere (Doebbeling et al., 2002).

A follow-up study (Time 2, conducted between 1999 and 2002) was designed to evaluate a

subset of the original veteran sample who met criteria for cognitive dysfunction, chronic

widespread pain (e.g., fibromyalgia, fibrositis), or depression at Time 1 (case group). Cognitive

dysfunction was defined as self-reported distress resulting from memory impairment, confusion,

disorientation, forgetfulness, or difficulty concentrating. A control group (comprising 38% of the

final sample) who did not meet criteria for any of the three aforementioned conditions at time 1

also was included in this Time 2 assessment. Inclusion criteria for both groups required that each

individual have his or her address in Iowa or in one of Iowa’s six surrounding states (IL, MO, NE,

SD, MN, and WI). A total of 563 participants completed the measures described below. Roughly

three-quarters of the total sample was deployed in the Gulf during the War. The large majority of

participants were male (88%) and Caucasian (97%) (mean age = 39.2 years).

2.2. Measures

Participants underwent a full day of assessment at The University of Iowa General Clinical

Research Center. Assessment consisted of the administration of several self-report questionnaires

designed to measure aspects of personality and physical, social, and mental well being; a

neuropsychological testing battery; a semi-structured psychiatric interview; and a complete

medical examination. For the purposes of this study, the following measures were examined.

2.2.1. Structured clinical interview for DSM-IV-patient edition (SCID-I/P)

The SCID (First, Spitzer, Gibbon, & Williams, 1997) is a semi-structured interview designed

to assess current psychiatric disorders according to DSM-IV criteria. SCIDs were administered


by one of two trained interviewers. Separate, blind diagnoses were made on 30 separate

occasions from audiotapes of the SCID interviews (kappa >.80). All diagnoses were then

reviewed by one of two clinicians who utilized all available information from the aforementioned

assessment battery to derive a best-estimate diagnosis (this included the original SCID diagnoses,

but did not involve any information from the SNAP). This method attempts to maximize the

validity of each clinical diagnosis. Diagnostic ratings were recorded as 1 (presence of a

diagnosis) or 0 (absence of a diagnosis).

Current diagnoses of major depression and six anxiety disorders (generalized anxiety

disorder, post-traumatic stress disorder, panic disorder, agoraphobia, social phobia, and specific

phobia) were included in subsequent analyses. Unfortunately, very low base-rates (n = 7)

precluded the inclusion of obsessive-compulsive disorder. In addition, dysthymia was only

assessed if a diagnosis of major depression was not met. As a result of this atypical comorbidity

pattern (i.e., there was no overlap between the two diagnoses), dysthymia was not included in the

subsequent analyses.

Table 1 displays the prevalence rates for each disorder included in the study. Major depression

and generalized anxiety disorder (GAD) both were relatively common in this sample, whereas

panic disorder and agoraphobia showed the lowest prevalence rates. The relatively high

prevalence of post-traumatic stress disorder (PTSD) is predictable given the nature of this veteran

sample.

2.2.2. Schedule for nonadaptive and adaptive personality (SNAP)

The SNAP (Clark, 1993) is a 375-item, factor analytically derived self-report inventory with a

true-false format. As noted previously, the SNAP consists of three general temperament scales

(Negative Temperament, Positive Temperament, and Disinhibition) and 12 lower order trait

scales (see Table 2 for descriptions of each of the scales). The temperament scales are not

composites or weighted sums of the trait scales, but rather, are standalone scales that were

developed independently as part of the general temperament survey (GTS; Clark & Watson,

1990). The temperament scales are typically the strongest markers of the three factors underlying

the SNAP, with the trait scales also loading primarily on one of these three dimensions (Clark,

1993; see Table 2). Finally, it should be noted that the temperament and trait scales do not share

item content (with the exception of Disinhibition, which shares some item content with the

Impulsivity, Propriety, and Workaholism Trait Scales).

The scales’ validity has been substantiated in a number of studies (e.g., Ready, Watson, &

Clark, 2002; Reynolds & Clark, 2001; Vittengl, Clark, Owens-Salters, & Gatchel, 1999).


Table 1

Prevalence rates of current best estimate diagnoses

Diagnosis n %

Major depression 52 9.2

Post-traumatic stress disorder 41 7.3

Generalized anxiety disorder 39 6.9

Specific phobia 32 5.7

Social phobia 28 5.0

Agoraphobia 16 2.8

Panic disorder 12 2.1

Any anxiety disorder 118 20.9

Note. N = 563.

Moreover, they have demonstrated good internal consistency, discriminant validity, and test–

retest reliability across multiple samples (Clark et al., in press).

3. Results

3.1. Relations among diagnoses

Table 3 displays Pearson’s correlation coefficients between each of the best estimate

diagnoses as well as the actual number of comorbid cases between diagnoses. It should be noted

that the observed correlations may be somewhat attenuated as a result of the dichotomous nature

of the diagnostic variables (see MacCallum, Zhang, Preacher, & Rucker, 2002; Whitehead,

1993)—particularly when these variables show significantly different prevalence rates (as is

typically the case with categorical diagnostic data). In general, the correlations are fairly low. The

two exceptions to this are the associations between major depression and GAD (r = .39), and

between panic disorder and agoraphobia (r = .46). These correlations are consistent with prior

findings in this area (e.g., Krueger, 1999; Vollebergh et al., 2001; Watson, 2005). However, it


Table 2

Description of the 12 trait scales included in the Schedule for Nonadaptive and Adaptive Personality (SNAP)

Trait scale Description

1. Mistrust Pervasive suspiciousness and cynical attitudes towards others

2. Manipulativeness Willingness to use people for personal gain

3. Aggression The experience and expression of anger and related behaviors

4. Self-Harm Low self-esteem, parasuicidal behaviors and suicidal ideation

5. Eccentric Perceptions Unusual perceptions, cognitions, and beliefs

6. Dependency Low self-reliance and confidence in decision making

7. Exhibitionism Overt attention seeking

8. Entitlement Unrealistically positive self-regard; expectations of special treatment

9. Detachment Emotional and interpersonal distance

10. Impulsivity Tendency to act without thinking or planning ahead

11. Propriety Preference for traditional, conservative morality

12. Workaholism Tendency to perfectionism and self-imposed demands for excellence

Note. Scales 1–6 load primarily on the Negative Temperament factor; Scales 7–9 load primarily on the Positive

Temperament factor; Scales 10–12 load primarily on the Disinhibition factor (Clark, 1993).

Table 3

Correlations and number of comorbid cases among current best estimate diagnoses

MDD GAD PTSD SP PD AGOR PHOB

Major depression – 20 15 8 3 6 6

Generalized anxiety disorder .39 – 11 8 4 4 3

Post-traumatic stress disorder .26 .22 – 6 5 7 7

Social phobia .15 .20 .12 – 1 4 3

Panic disorder .11 .19 .22 .06 – 6 1

Agoraphobia .19 .15 .25 .18 .46 – 2

Specific phobia .08 .02 .12 .04 .01 .05 –

Note. The lower triangle displays correlations among diagnoses. The upper triangle displays the number of comorbid

cases (i.e., those that met criteria for both diagnoses). Correlations�j.09j are significant at P < .05; correlations�j.11j are

significant at P < .01; N = 563.

should be noted that both social phobia and specific phobia diagnoses evidence weaker than

expected associations with the remaining disorders (e.g., specific phobia correlated significantly

only with PTSD).

3.2. Diagnostic relations with the SNAP

Pearson’s correlation coefficients between individual best-estimate diagnoses and the

personality scales are presented in Table 4. As described earlier, because these diagnoses are

assessed dichotomously (i.e., present vs. not present), the associations among the personality and

diagnostic variables may be somewhat attenuated (see Watson, Gamez, & Simms, 2005).

We will summarize key findings in each of the Big Three domains. First, the results regarding

the SNAP Negative Temperament Scale were generally consistent with our predictions. As

hypothesized, its strongest associations were with major depression (r = .38), PTSD (r = .35),

and GAD (r = .31). In order to compare differences between correlations more systematically,

the Williams modification of the Hotelling Test for two correlations with one common variable

was conducted (Kenny, 1987). Consistent with our prediction, correlations of Negative

Temperament with these three disorders (major depression, PTSD, and GAD) were significantly

higher than those for social phobia, panic disorder, agoraphobia, and specific phobia (across the

12 individual comparisons, the z’s ranged from 2.10 to 4.86; all P’s < .05, two-tailed). As

expected, Negative Temperament was most weakly related to specific phobia (r = .12); it should

be noted, however, that this correlation was not significantly lower than those for social phobia

(r = .16), panic disorder (r = .18), or agoraphobia (r = .20) (z’s ranged from .69 to 1.40, all

P’s > .05).

This same basic pattern was observed across the other scales within the Negative

Temperament domain. Generally speaking, these scales all correlated more strongly with major

depression, GAD, and PTSD than with the other diagnoses. Collapsing across the seven SNAP


Table 4

Correlations between current best estimate diagnoses and the Schedule for Nonadaptive and Adaptive Personality (SNAP)

Diagnoses MDD GAD PTSD SP PD AGOR PHOB

Negative Temperament .38 .31 .35 .16 .18 .20 .12

Mistrust .31 .22 .29 .12 .08 .15 .07

Manipulativeness .09 .10 .08 .04 .11 .09 .06

Aggression .21 .20 .26 .07 .11 .16 .08

Self-Harm .41 .31 .25 .19 .12 .17 .06

Eccentric Perceptions .18 .14 .28 .16 .08 .10 .08

Dependency .16 .16 .08 .08 .06 .01 �.01

Positive Temperament �.25 �.22 �.13 �.16 �.11 �.10 �.05

Exhibitionism �.10 �.07 �.10 �.12 �.05 �.08 �.08

Entitlement �.07 �.05 �.03 �.08 �.03 �.08 �.04

Detachment .24 .20 .23 .17 .14 .15 .07

Disinhibition .10 .07 .09 .04 .06 .11 .01

Impulsivity .07 .10 .07 .06 .05 .04 �.02

Propriety .03 .01 .00 .02 �.06 �.07 .05

Workaholism .13 .10 .16 .04 .05 .00 .01

Note. Correlations �j.09j are significant at P < .05; correlations �j.11j are significant at P < .01. All correlations �j.20jare highlighted; MDD, major depression; GAD, generalized anxiety disorder; PTSD, post-traumatic stress disorder; SP,

social phobia; PD, panic disorder; AGOR, agoraphobia; PHOB, specific phobia.

scales comprising this domain, 13 of the 21 correlations (61.9%) with major depression, GAD

and PTSD were .20 or greater, and 6 (28.6%) were .30 or greater; in sharp contrast, only 1 of the

28 correlations (3.6%) with social phobia, panic disorder, agoraphobia, and specific phobia was

as high as .20.

Many of the scales showed relatively non-specific associations with multiple disorders. For

instance, paralleling Negative Temperament, Mistrust had very similar correlations with major

depression (.31) and PTSD (.29). Two scales, however, showed specific links to particular

disorders. First, Eccentric Perceptions had a significantly stronger correlation with PTSD (.28)

than with any other diagnosis (r’s ranged from .08 to .18) (across the six individual comparisons,

the z’s ranged from 2.03 to 3.70; all P’s < .05, two-tailed). Second, Self-Harm was the strongest

correlate of major depression (r = .41) and was associated more strongly with depression than

with any other disorder (z’s ranged from 2.36 to 6.61; all P’s < .05, two-tailed).

Consistent with expectations, depression (r = �.25) and social phobia (r = �.16) both were

significantly related to the SNAP Positive Temperament Scale. Unexpectedly, however, Positive

Temperament also correlated moderately with GAD (r = �.22). Supporting the predictions of the

integrative hierarchical model (Mineka et al., 1998), Positive Temperament had a stronger

negative correlation with major depression than with PTSD, panic disorder, agoraphobia, and

specific phobia (z’s ranged from 2.40 to 3.59, all P’s < .05, two-tailed); the comparisons

involving GAD (z = .67) and social phobia (z = 1.69) failed to reach significance, however. In

contrast, social phobia’s association with Positive Temperament did not differ significantly from

any other disorder, with the single exception of specific phobia (z = 1.98, P < .05, two-tailed).

With regard to the other scales within this domain, only Detachment showed moderate links to

the diagnoses, correlating most strongly with major depression (.24), PTSD (.23), and GAD

(.20). Exhibitionism and Entitlement displayed consistently weak associations, with no

coefficient exceeding j.15j.Finally, the Disinhibition domain clearly showed the weakest links to these disorders. Only 6

of the 28 correlations (21.4%) were as high as j.10j and only one coefficient (3.6%) exceeded

j.15j.

3.2.1. Partial correlations controlling for Negative Temperament

Do the other SNAP scales contain incremental predictive power beyond that attributable to

general Neuroticism/Negative Emotionality? We investigated this issue by computing partial

correlations between the best-estimate diagnoses and the SNAP scales, controlling for Negative

Temperament; these partial correlations are presented in Table 5. The results indicate that

controlling for Negative Temperament eliminated a substantial portion of the predictive power of

these other scales. Note, for example, that only 1 of the 42 correlations (2.4%) between the SNAP

scales and panic disorder, agoraphobia, and specific phobia remained statistically significant after

controlling for Negative Temperament. Overall, only 4 of the 98 correlations (4.1%) were j.15j or

greater. Specifically, Self-Harm correlated .26 with major depression and .17 with GAD, Positive

Temperament correlated �.16 with major depression, and Eccentric Perceptions correlated .15

with PTSD.

As mentioned previously, low levels of Extraversion/Positive Emotionality have been found to

be fairly common among those with unipolar mood and anxiety disorders. In addition, Bienvenu

et al. (2001) found that controlling for both Neuroticism and Extraversion eliminated a

considerable amount of comorbidity. As a result, we computed correlations that also partialled

out the effects of Positive Temperament. This analysis resulted in slightly lowered correlations,

but did not significantly change the findings presented in Table 5.


4. Discussion

4.1. Summary of results

As expected, Negative Temperament was significantly related to all of the assessed diagnoses

(although minimally so in the case of specific phobia). Positive Temperament also showed its

hypothesized relations with depression and social phobia. One unexpected finding, however, was

that GAD was similarly related to Positive Temperament; this association most likely reflects the

relatively high comorbidity between depression and GAD (see Table 3). Finally, Disinhibition

showed no meaningful associations with any of the disorders included in the study.

Consistent with our expectations, although every disorder was significantly related to Negative

Temperament, the magnitude of these correlations varied widely. As predicted, Negative

Temperament had significantly stronger correlations with depression, GAD, and PTSD than with

panic disorder, agoraphobia, social phobia, and specific phobia. Furthermore, this same basic

pattern was observed across all of the SNAP scales comprising the Negative Temperament domain.

In general, the lower order SNAP personality traits did not show specific associations with

particular disorders. However, two traits (Self-Harm and Eccentric Perceptions) evidenced true

specificity, in that they had significantly stronger correlations with one disorder relative to all of

the others. Although they were not initially hypothesized, the findings regarding Self-Harm are

consistent with prior research that generally has found suicidality to be highest for those with

depression, relative to other disorders (e.g., Wilson, Nathan, O’Leary, & Clark, 1996). In

addition, Clark, McEwen, Collard, and Hickok (1993) specifically linked chart-rated depressed

mood and vegetative signs to suicide proneness. This finding is particularly salient, given that the

correlation between Self-Harm and depression remained significant and moderate in magnitude,

even after controlling for a powerful general predictor of psychopathology (Negative

Temperament; see Table 5).


Table 5

Correlations between current best estimate diagnoses and the Schedule for Nonadaptive and Adaptive Personality (SNAP)

(controlling for Negative Temperament)

Diagnoses MDD GAD PTSD SP PD AGOR PHOB

Negative Temperament – – – – – – –

Mistrust .12 .04 .10 .03 �.03 .04 �.01

Manipulativeness �.05 �.02 �.05 �.02 .05 .02 .01

Aggression �.01 .02 .08 �.03 .02 .06 .01

Self-Harm .26 .17 .07 .12 .03 .07 �.02

Eccentric Perceptions .01 .00 .15 .10 .00 .01 .02

Dependency .03 .06 �.05 .02 �.01 �.07 �.05

Positive Temperament �.16 �.14 �.03 �.12 �.06 �.04 �.01

Exhibitionism �.07 �.05 �.07 �.11 �.04 �.07 �.07

Entitlement �.07 �.04 �.02 �.08 �.02 �.07 �.03

Detachment .09 .07 .10 .12 .07 .07 .02

Disinhibition �.01 �.02 �.01 .00 .02 .06 �.03

Impulsivity �.01 .04 �.01 .03 .02 .00 �.05

Propriety �.02 �.04 �.05 .00 �.08 �.10 .04

Workaholism .04 .02 .08 .00 .00 �.06 �.03

Note. Correlations �j.09j are significant at P < .05; correlations �j.11j are significant at P < .01. All correlations �j.20jare highlighted.

As noted earlier, Eccentric Perceptions was found to be a specific predictor of PTSD (see

Tables 4 and 5). Paralleling the pattern observed with Self-Harm, it is noteworthy that this scale had

incremental predictive power beyond that attributable to Negative and Positive Temperament. This

result is perhaps not surprising, in light of the fact that the DSM-IV Cluster B symptom criteria for

PTSD involves several odd and unusual experiences (e.g., hallucinations, illusions, and dissociative

flashback episodes). In addition, several studies have found that dissociative experiences predict the

onset of PTSD (Harvey & Bryant, 1999; Marmar et al., 1994).

Of course, these results require replication in future research. To date, there have been few

factors that have been found to distinguish between individual mood and anxiety disorders. If

Self-Harm and Eccentric Perceptions are indeed shown to be relatively specific markers of

depression and PTSD, respectively, they may provide important insights that can contribute

toward a better understanding of these disorders, as well as the future development of improved

structural models of anxiety and depression.

4.2. Implications for diagnostic organization

Our results add to a growing body of evidence that has potentially important implications for

the organization of the mood and anxiety disorders in DSM-V. Extensive data establish that GAD

is more closely linked to major depression than to the other current anxiety disorders (e.g.,

Brown, Campbell et al., 2001; Mineka et al., 1998) and that both disorders may share a common

genetic diathesis (Kendler, Neale, Kessler, Heath, & Eaves, 1992; Kendler et al., 1995; Kendler,

Prescott, Myers, & Neale, 2003). Our data contribute to this evidence by demonstrating that

depression and GAD (a) were strongly comorbid and (b) generally showed very similar

associations with the SNAP scales.

Furthermore, findings from the current study suggest that PTSD can be linked conceptually to

both depression and GAD. Namely, depression, GAD, and PTSD show particularly strong

correlations with Negative Temperament (significantly higher than any of the other diagnoses

included in our study). These common links may be largely explained by an examination of the

diagnostic criteria for these disorders. That is, depression, GAD, and PTSD all prominently

feature a number of symptoms that assess non-specific distress.

4.3. Strengths and limitations

This study had several notable strengths. First, the simultaneous examination of several

different mood and anxiety disorders allowed for a direct examination of the specificity versus

non-specificity of relations across multiple disorders. Second, the use of the SNAP scales

permitted a more comprehensive and detailed analysis of personality-disorder relations than in

most previous studies in this area. Third, our use of current diagnoses eliminated problems

associated with retrospective recall biases. Fourth, we were able to establish the incremental

predictive power of Self-Harm and Eccentric Perceptions by controlling for the non-specific

influence of Negative Temperament. Finally, the large size of our sample (N = 563) gave us

sufficient statistical power to examine these issues in a precise and rigorous manner.

At the same time, however, we also must acknowledge three significant limitations of our

study. First, our sample consisted entirely of Gulf War veterans. In addition, our participants were

predominantly male and almost exclusively Caucasian. As a result, it is unclear how well our

results would generalize to other samples, such as community-dwelling adults or clinical

patients. Accordingly, it will be important to replicate these results in other samples. Second, we


were not able to include diagnoses of obsessive-compulsive disorder and dysthymia in the

analyses. Third, the cross-sectional nature of the study precludes us from drawing causal

conclusions or teasing apart state and trait effects. Finally, it is important to note that some

diagnoses exhibited relatively low base rates (i.e., panic disorder and agoraphobia; see Table 1).

These low base rates may have served to attenuate the observed correlations between these

disorders and the SNAP (see discussions by MacCallum et al., 2002; Whitehead, 1993).

4.4. Future research

Because Self-Harm was shown to have considerable predictive power in the current study,

future research should examine what other psychological constructs or disorders may be

associated with this potentially important dimension. More generally, additional research is

needed to clarify how the SNAP scales are related to psychopathology. Finally, the relations

between the mood and anxiety disorders and the specific lower order traits included in other

prominent Big Three and Big Five inventories, such as the Multidimensional Personality

Questionnaire (Tellegen, 1982) and the Revised NEO Personality Inventory (Costa & McCrae,

1992b) also should be examined.

Although the current study examined personality’s association with different mood and

anxiety disorders, we are unable to draw any conclusions regarding vulnerability. In this regard,

studies have shown that personality measures may be influenced by ongoing affective states, such

as current depression (Du, Bakish, Ravindran, & Hrdina, 2002; Griens, Jonker, Spinhoven, &

Blom, 2002; Liebowitz, Stallone, Dunner, & Fieve, 1979) and anxiety (Reich, Noyes, Coryell, &

O’Gorman, 1986). Interestingly, Clark et al. (2003) demonstrated that state and trait effects could

be separated and that only the trait variance was able to predict treatment outcome. Additional

longitudinal research that measures personality before the onset of overt psychopathology (e.g.,

Hirschfeld et al., 1999) would play a valuable role in teasing apart these state and trait effects.

Future studies also should examine relations between personality and dimensional measures

of psychopathology. To date, almost all of the research in this area has focused on categorical

diagnoses. These dichotomous classifications can result in a substantial loss of information (see

Brown, Campbell et al., 2001; Watson, 2005). Moreover, dimensional analyses can circumvent

the base rate problems discussed earlier (Watson et al., 2005) and would likely result in stronger

observed associations among personality and psychopathology variables. Consequently,

dimensionally based research that focuses on symptom level analyses may provide a somewhat

clearer perspective on the relations between personality and psychopathology (see Watson et al.,

2005).

Finally, although the current study adds to our knowledge about the structure of depression and

the anxiety disorders, further research needs to be conducted to explicate these findings further.

Clarifying the structure of these disorders obviously has broad and important implications for the

future diagnostic organization of these syndromes. Moreover, further articulation of the unique

components of the mood and anxiety disorders will enhance our understanding of these disorders

and lead to improvements in our ability to diagnose and treat them.

Acknowledgments

This work was partially supported by CDC Cooperative Agreement U50/CCU711513 and

Department of Defense Grant DAMD17-97-1. We would like to thank Lee Anna Clark, Michael

O’Hara, Donald Black, and Valerie Forman for their help in the preparation of this manuscript.


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