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Anxiety Disorders and Personality Disorders Comorbidity

Abstract and Keywords

Symptoms of all the major personality disorder (PD) clusters have been noted in higher than expected numbers in patients with anxiety disorders; however, Cluster C characteristics appear particularly common. High neuroticism and some personality disorder traits predict later onset of anxiety disorders; conversely, anxiety disorders in adolescence appear to predict onset of PDs by adulthood. Temperament/personality traits such as behavioral inhibition, neuroticism, and Cluster C characteristics also appear to relate to anxiety disorders familially/genetically, and it remains unclear whether inherited personality traits are causal risk factors versus markers of susceptibility for anxiety disorders. Patients with comorbid anxiety and PDs, including Cluster B disorders, appear to have more functional impairment and suicidality. Patients with anxiety disorders and PDs appear to be more ill than those without PDs, but both groups generally respond to treatment. In fact, successful treatment of panic disorder often results in partial “normalization” of personality.

Keywords: anxiety disorders, comorbidity, personality, personality disorders

Anxiety disorders are strongly related to normal personality traits, as well as personality disorder traits. In this chapter, we examine the evidence for ways in which particular personality traits may relate to anxiety disorders, as well as clinical implications of particular personality profiles in patients with anxiety disorders. In this endeavor, we mainly focus on the recent literature. This is not meant to be an exhaustive review; rather, it is meant to illustrate issues of importance to this field using selected examples.

Theoretical and Practical Issues

Dimensions Versus Categories in Personality Disorder Assessment

Leaders in the personality/personality disorders field have continued to emphasize the relevance of considering personality in dimensional terms (i.e., less versus more of a trait), rather than categorical terms (i.e., presence or absence of so-called disorder) (Widiger, Simonsen, Krueger, Livesley, & Verheul, 2005). It is likely that the next version of the Diagnostic and Statistical Manual of Mental Disorders (DSM) will reflect this change. As we shall outline, personality disorder dimensions and normal personality dimensions are important to consider in patients with anxiety disorders.

Two normal or general personality dimensions that appear in most personality taxonomies, and seem particularly relevant to the anxiety disorders, are neuroticism and extraversion. Neuroticism (also known as negative affectivity or negative emotionality) refers to one's tendency to experience negative emotions and cope poorly with stress. Persons high in neuroticism tend to feel transiently anxious, sad, angry, self-conscious, and vulnerable more often than persons who are low in neuroticism, who might be considered relatively “unflappable.” Extraversion, on the other hand, refers to a person's tendency to (p. 588) be venturesome, energetic, assertive, sociable, and experience positive emotions (e.g., joy). Persons high in extraversion tend to be warm, gregarious, active, excitement-seeking, and emotionally bright compared to more introverted persons. Neuroticism and extraversion tend to be normally distributed in the population, like height or intelligence. These characteristics are also relatively independent of each other; one can be high in neuroticism and extraversion, high in one but not the other, or low in both.

Relationships Between Personality Disorder Traits and “Normal” or “General” Personality Traits

It is worth keeping in mind how personality disorder traits and normal personality traits relate. In a recent meta-analysis, Saulsman and Page noted that high neuroticism and disagreeableness (antagonism) were associated with each of the personality disorders. Borderline and dependent traits correlated particularly strongly with neuroticism, while avoidant traits correlated strongly with both neuroticism and introversion. Schizotypal traits also correlated relatively strongly with neuroticism and introversion (Saulsman & Page, 2004).

Generalized Anxiety Disorder as a Dimensional Construct

Some authors have suggested that generalized anxiety disorder (GAD) is better understood as a dimensional construct, as opposed to a categorical illness (Akiskal, 1998). Similar to the usual conception of personality traits, GAD is often described as “lifelong.” That is, having a tendency toward high levels of stress and anxiety seems to describe what many patients with GAD are “like,” rather than what they “have.” It is important to note that GAD is not completely unique in this respect, as the same could be said about some patients with social phobia (who report early pervasive distress in the context of social evaluation).

Comorbidity as Artifact: Overlapping Criteria and Constructs

Some authors have noted that strong associations between certain personality traits and anxiety disorders could be explained, at least in part, by overlap in criteria/constructs. For example, neuroticism and GAD, and avoidant personality disorder and social phobia, resemble one another to a great extent. Hettema and colleagues (Hettema, Prescott, & Kendler, 2004) have pointed out that some criteria for GAD (irritability, worrying, and nervousness) overlap with questions assessing neuroticism in the Eysenck Personality Questionnaire (Eysenck & Eysenck, 1975). Similarly, the DSM-IV (American Psychiatric Association, 1994) diagnostic criteria for avoidant personality disorder and social phobia are not identical, but do overlap in content (see Table 1). Though psychoanalytic writings sometimes mentioned obsessive-compulsive personality traits as being on a continuum with obsessive-compulsive disorder (OCD), it is notable that the current diagnostic criteria do not overlap, with one exception (hoarding). Though hoarding is not mentioned as a specific example of an OCD symptom in the DSM-IV, the associated mental phenomena and behaviors often appear to meet OCD criteria.

Relations Between Personality Traits and Anxiety Disorders

Normal Personality Traits and Anxiety Disorders: A Descriptive Summary

There are fairly consistent relationships between the general personality traits, neuroticism and extraversion, and anxiety disorders, in both clinical and nonclinical samples (Bienvenu & Stein, 2003). For instance, Bienvenu and colleagues studied the (p. 589) distribution of normal personality traits in persons with and without lifetime anxiety disorders in the general population of east Baltimore (Bienvenu et al., 2004). Although the study group was oversampled for psychopathology, neuroticism and extraversion factor T-scores (mean = 50, standard deviation = 10) were fairly normally distributed in the sample and similar to external population norms (see Figure 1—center). Persons with specific phobia had neuroticism and extraversion scores that were similar to those of subjects without anxiety or depressive disorders (Figure 1—bottom right). In contrast, persons with social phobia or agoraphobia tended to be quite high in neuroticism, introverted, or both (Figure 1—right). Finally, persons with panic disorder, OCD, or GAD tended to be high in neuroticism and average, overall, in extraversion (Figure 1—left). Notably, there was substantial personality variability in each diagnostic group; for example, there were subjects with panic disorder who were not high in neuroticism, and there were individuals with social phobia who were not particularly high in neuroticism or low in extraversion.

Table 1. Overlapping DSM-IV Criteria for Social Phobia and Avoidant Personality Disorder

Social Phobia

Avoidant Personality Disorder

• Fear of social or performance situations in which the person is exposed to unfamiliar people or to possible scrutiny by others. The individual fears that he or she will act in a way that will be humiliating or embarrassing.

• Is preoccupied with being criticized or rejected in social situations.

• Is unusually reluctant to take personal risks or to engage in any new activities because they may prove embarrassing.

• Feared situations are avoided or endured with anxiety or distress.

• Avoids occupational activities that involve significant interpersonal contact, because of fears of criticism, disapproval, or rejection.

Comorbidity among Axis I conditions is associated with greater treatment-seeking (Andrews, Slade, & Issakidis, 2002). Comorbidity among these conditions is also associated with high neuroticism (Andrews et al., 2002; Bienvenu et al., 2001), which may also relate to treatment-seeking.

Personality Disorder Traits and Anxiety Disorders in Clinical Settings: A Descriptive Summary

Symptoms of all of the major personality disorder groupings (i.e., odd, dramatic, and anxious clusters) have been noted in higher than expected numbers in patients with anxiety disorders (Bienvenu & Stein, 2003). In a large sample of outpatients with a primary diagnosis of anxiety disorder, Sanderson et al. found that at least one personality disorder was present in 35% (Sanderson, Wetzler, Beck, & Betz, 1994). By far, the most common personality disorders were from Cluster C (the “anxious/fearful” cluster), and patients with specific phobia had the lowest rates of personality disorders. In another fairly large sample comprising inpatients and outpatients with anxiety disorders, Skodol et al. found that 62% had at least one personality disorder (Skodol et al., 1995). Panic disorder was associated with borderline, avoidant, and dependent personality disorders; social phobia was associated with avoidant personality disorder; obsessive-compulsive disorder was associated with avoidant and obsessive-compulsive personality disorders; and specific phobia was not associated with any personality disorder. In the Harvard/Brown Anxiety Research Project, 24% of the patients had at least one personality disorder. Avoidant, obsessive-compulsive, dependent, and borderline were the most common.

The Collaborative Longitudinal Personality Disorders Study (CLPS) assessed comorbidity in patients selected for personality disorders. In this study, there were particularly high rates of posttraumatic stress disorder (PTSD) in patients with borderline personality disorder (46.9%), and there were particularly high rates of social phobia in patients with avoidant personality disorder (38.2%) (McGlashan et al., 2000). However, several other findings deserve mention. For example, 40.7% of patients with schizotypal personality disorder had panic disorder, and 33.7% had PTSD. Also, 29.4% of patients with obsessive-compulsive personality disorder had GAD.

Personality Disorder Traits and Anxiety Disorders in Community Settings: A Descriptive Summary

Until recently, there were few general population studies of personality disorder/anxiety disorder comorbidity, with a few exceptions. For example, Nestadt et al. found that compulsive personality traits were strongly related to GAD in the Baltimore Epidemiologic Catchment Area study (Nestadt, Romanoski, Samuels, Folstein, & McHugh, 1992).

 Anxiety Disorders and Personality Disorders ComorbidityClick to view larger

Fig. 1 Distribution of neuroticism and extraversion scores in persons with lifetime anxiety disorders in a community sample.

Note: OCD = obsessive-compulsive disorder; GAD = generalized anxiety disorder. Anxiety disorder diagnoses are not mutually exclusive, and the panel depicting the entire sample includes persons with anxiety disorders.

In the recent National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), personality disorders and Axis I conditions were assessed in a very large U.S. sample. Though some personality disorders were not assessed in the first wave (i.e., borderline, narcissistic, and schizotypal), this study provides a remarkable opportunity to assess personality/anxiety disorder comorbidity, unbiased by treatment-seeking behavior. In the NESARC, anxious cluster personality traits (i.e., avoidant, dependent, and, to a lesser extent, obsessive-compulsive) appear particularly common in general population subjects with anxiety disorders (Grant et al., 2005a). Avoidant and dependent traits were associated, in particular, with GAD and social phobia (Grant et al., 2005b). Similar to results in clinical samples, avoidant personality disorder was more strongly associated with social phobia than any other personality disorder (Grant et al., 2005c). Epidemiologic studies like the NESARC employ nonclinician interviewers and fully structured interviews, as opposed to clinicians and semistructured interviews (with “cross-examination” to establish the presence (p. 590) (p. 591) or absence of given criteria). Nevertheless, the very large sample size and rigorous survey methodology provide the field with important information.

In sum, anxiety disorders appear most strongly associated with Cluster C traits in both clinical and community samples. It will be interesting to determine whether borderline and schizotypal traits are also associated with anxiety disorders in the general population, or whether this comorbidity in clinical samples is due to Berkson's bias (Berkson, 1946).

Possible Causal Relationships

The associations outlined earlier lead to important questions regarding why personality traits relate to anxiety disorders. We review the evidence in response to 3 questions: (1) Are personality traits risk factors for anxiety disorders? (2) Are personality traits shaped by the experience of having an anxiety disorder? (3) Are personality traits and anxiety disorders manifestations of the same causes?

Are Personality Traits Risk Factors for Anxiety Disorders? Whether personality traits act as risk factors for anxiety disorders can be addressed by examining personality traits and anxiety disorders longitudinally.

Krueger examined general personality traits and anxiety disorders longitudinally in a cohort of young people in Dunedin, New Zealand. High baseline negative emotionality (an analogue of neuroticism) in late adolescence predicted onset of anxiety disorders by young adulthood (Krueger, 1999). Bramsen and colleagues measured predeployment personality traits in individuals involved in United Nations peacekeeping activities in the former Yugoslavia, using a short form of the Dutch Minnesota Multiphasic Personality Inventory (Bramsen, Dirkzwager, & van der Ploeg, 2000). Psychoneuroticism was a very strong predictor of onset of PTSD symptoms, second only to traumatic event exposure in predictive strength. Fauerbach and colleagues examined personality traits in survivors of severe burns. Higher baseline neuroticism and lower baseline extraversion predicted onset of PTSD during the following year in this group (Fauerbach, Lawrence, Schmidt, Munster, & Costa, 2000). Hayward and colleagues, in their 4-year, prospective study of high school students, found that high negative affectivity (another analogue of neuroticism) was a risk factor for 4-symptom panic attacks during adolescence (Hayward, Killen, Kraemer, & Taylor, 2000).

What about personality disorder traits? The Children in the Community Study provided evidence that schizotypal, antisocial, borderline, histrionic, and dependent personality traits present in adolescence and early adulthood (between ages 14 and 22) were associated with increased risk of having an anxiety disorder by middle adulthood (mean age of 33), controlling for baseline anxiety disorders (Johnson, Cohen, Kasen, & Brook, 2006). Bachar and colleagues showed that, among patients who presented to an emergency room following traumatic events, having a high narcissistic vulnerability at 1 week postevent was related to developing PTSD at 1 and 4 months postevent (Bachar, Hadar, & Shalev, 2005).

These studies show that personality traits prospectively predict the onset of anxiety disorders; however, it is important to consider that these studies do not fully elucidate some possible causal mechanisms involved. For example, personality traits could, in these cases, be (earlier) manifestations of genetic and/or environmental influences that also affect risk for anxiety disorders. It is also possible that personality traits are, in some cases, prodromal symptoms of anxiety disorders.

Are Personality Disorder Traits Consequences of Anxiety Disorders? It is commonly believed that personality is still being formed during childhood, adolescence, and perhaps young adulthood. Thus, it may be that personality traits are shaped by the experience of having (or having had) an anxiety disorder, at least in adolescence. We know of no studies, at present, that have assessed this possibility for normal personality traits.

Lewinsohn and colleagues followed subjects recruited from representative schools in western Oregon and found that adolescent anxiety disorders predicted schizotypal, schizoid, borderline, avoidant, and dependent personality traits in early adulthood, controlling for other adolescent Axis I disorders (Lewinsohn, Rohde, Seeley, & Klein, 1997). Unfortunately, Lewinsohn and colleagues did not assess the possibility that these personality traits might have already been present in adolescence. Kasen and colleagues took this area of research a step further in similar analyses of data from the Children in the Community Study (Kasen et al., 2001). They found that adolescent anxiety disorders predicted Cluster A (“odd cluster”) and Cluster C personality disorders in young adulthood (when controlling for adolescent personality disorders and several other potentially relevant variables). In a further analysis of the data from the Children in the Community Study, Goodwin and colleagues found that having panic attacks during adolescence was associated with higher prevalence of having any personality disorder during young adulthood (p. 592) and more than threefold increased risk of having a Cluster C personality disorder, after adjusting for adolescent personality disorders (Goodwin, Brook, & Cohen, 2005).

However, the caveat about the possibility of personality traits and anxiety disorders having common etiologies still holds, in this case with personality traits being the later manifestations.

Are Personality Disorder Traits and Anxiety Disorders Manifestations of a Common Etiologic Process? Family studies suggest that personality traits may represent at least part of what is inherited in anxiety disorders. For example, a series of studies has related anxiety disorders to Kagan and colleagues' “behavioral inhibition to the unfamiliar” (Kagan, Reznick, & Snidman, 1987). Behaviorally inhibited children are cautious, quiet, introverted, and shy in unfamiliar situations. Rosenbaum and colleagues have shown that, when parents with panic disorder and agoraphobia were compared to control parents, the former group had higher rates of behaviorally inhibited children. In addition, when behaviorally inhibited children were compared with control children, the former group had higher rates of familial anxiety disorders (Rosenbaum et al., 1993). Similarly, Reich found that avoidant and dependent personality traits were more common in first-degree relatives of patients with panic disorder compared with relatives of controls (Reich, 1991). Also, Samuels and colleagues found that obsessive-compulsive personality traits and neuroticism were elevated in first-degree relatives of patients with OCD, compared with relatives of controls (Samuels et al., 2000). In addition, Stein and colleagues found that trait anxiety and harm avoidance (related to neuroticism and introversion) were elevated in relatives of probands with generalized social phobia, compared with relatives of control probands (Stein, Chartier, Lizak, & Jang, 2001). Finally, in a study of the Swedish general population, Tillfors et al. found that the risks for both social phobia and avoidant personality disorder were elevated if the subjects' parents had excessive social anxiety. The authors concluded that the two disorders reflect dimensions in a spectrum of social anxiety (Tillfors, Furmark, Ekselius, & Fredrikson, 2001). A caveat when considering family study results is that these designs do not differentiate genetic from common environmental effects.

In the past two decades, researchers have begun to use twin designs to determine whether genetic factors may help explain why personality traits are so strongly related to most anxiety disorders. For example, Jardine and colleagues used an Australian twin sample and found that genetic variation in symptoms of anxiety was largely dependent on the same factors that affected the neuroticism trait (Jardine, Martin, & Henderson, 1984). Similarly, Hettema and colleagues, using data from the Virginia Twin Registry, found cross-sectional evidence that the genes that influence neuroticism also influence risk for a variety of anxiety disorders (Hettema, Neale, Myers, Prescott, & Kendler, 2006).

Genetically informative longitudinal studies (e.g., twin studies) would be useful in ultimately determining whether inherited personality traits are themselves true risk factors for anxiety disorders, or whether personality traits are simply markers of an inherited spectrum that includes anxiety disorders (Bienvenu & Stein, 2003).

Clinical Course in Patients With Anxiety Disorders and Comorbid Personality Disorders

Effect of Comorbidity on Clinical Features and Severity of Anxiety Disorders

Patients with comorbid anxiety and personality disorders appear to suffer more functional impairment and have increased risk for suicidality. Dammen et al. found that panic disorder patients with personality disorders reported higher psychological distress and suicidal ideation, relative to individuals with panic disorder and no personality disorder (Dammen, Ekeberg, Arnesen, & Friis, 2000). Iketani and colleagues found that, in panic disorder patients seeking outpatient treatment, all who had made serious suicide attempts had a comorbid personality disorder. In particular, there was a significant association between suicide attempts and comorbid Cluster B (“dramatic cluster”) personality disorders, especially borderline or histrionic (Iketani et al., 2004). Ozkan and Altindag found that panic disorder patients with comorbid personality disorders had lower Global Assessment of Functioning (GAF) scores. In addition, the presence of comorbid paranoid or borderline personality disorder predicted suicide attempts, and avoidant personality disorder predicted suicidal ideation (Ozkan & Altindag, 2005). Tenney and colleagues studied patients with OCD and found that those with a comorbid personality disorder had higher overall levels of functional impairment, as indicated by lower GAF scores (Tenney, Schotte, Denys, van Megen, & Westenberg, 2003). Baseline data from the CLPS showed that females with both borderline personality disorder and PTSD had lower GAF scores, and a higher percentage of them had more (p. 593) than one lifetime hospitalization than those with either disorder alone. Among women with PTSD, an additional diagnosis of borderline personality disorder was associated with greater suicide proneness (Zlotnick et al., 2003). Goodwin and Hamilton found that individuals with an anxiety disorder and antisocial personality disorder had more suicidal ideation and suicide attempts, compared to those with either disorder alone (Goodwin & Hamilton, 2003). Similarly, in two community surveys (the National Comorbidity Survey and the Ontario Health Survey), individuals with comorbid anxiety and antisocial behavior were found to have poorer quality of life and increased suicidal ideation compared to those with either syndrome alone (Sareen, Stein, Cox, & Hassard, 2004).

Effect of Comorbidity on Prognosis of Anxiety Disorders

Personality disorder traits have often been noted to predict worse treatment outcomes in patients with Axis I conditions (Reich & Vasile, 1993). In a review of factors that predict nonresponse to pharmacotherapy in panic disorder patients, Slaap and den Boer concluded that comorbid personality disorder traits were among the strongest predictors of nonresponse to pharmacotherapy, in both short-term and long-term studies (Slaap & den Boer, 2001). Massion et al. found that patients with GAD and comorbid avoidant or dependent personality disorders had a lower probability of remission at 5 years than those without personality disorders (Massion et al., 2002). In a treatment study of patients with panic disorder, Berger et al. found that comorbid personality disorders, particularly avoidant, were associated with a delayed response to treatment (Berger et al., 2004). Prasko et al. found that, in the short-term, the combination of cognitive behavioral therapy and pharmacotherapy were more effective in patients with panic disorder and/ or agoraphobia without personality disorders, compared to those with a comorbid personality disorder (Prasko et al., 2005).

Encouragingly, as noted by Dreessen and Arntz, when baseline severity of illness is taken into account, patients with substantial personality disorder traits and anxiety disorders often seem to improve as much with treatment as patients without substantial personality pathology (Dreessen & Arntz, 1998). That is, there appears to be “parallel” improvement. It seems likely that such patients will need more therapeutic attention, such as intensive and individualized cognitive behavioral interventions, and perhaps additional medications, in order to experience relief from their anxiety symptoms (Berger et al., 2004; Reich, 2003).

Special Considerations Regarding Obsessive-Compulsive Disorder With Schizotypal Personality Disorder. Patients with OCD and substantial schizotypal personality traits frequently seem to have poorer responses to treatment (Dreessen & Arntz, 1998). While schizotypal personality disorder may not be particularly common among patients with OCD (Samuels et al., 2000), its relationship to poor treatment outcome is fairly consistent (Fricke et al., 2005). Results of a recent study by Moritz and colleagues suggest that it may be the so-called positive schizotypal symptoms (e.g., unusual perceptual experiences) that predict failure of traditional treatments (e.g., serotonin reuptake inhibitors and behavioral therapy) (Moritz et al., 2004). These positive symptoms appear discontinuous from normal personality traits, unlike the avoidant and dependent personality traits that are so common among persons with anxiety disorders. As Moritz and colleagues suggest, patients with positive schizotypal symptoms and OCD may respond better to low-dose atypical neuroleptics and specifically tailored behavioral interventions.

Impact of Treatment of Anxiety Disorders on Comorbid Personality Disorders

There is evidence to suggest that, in individuals with comorbid panic and personality disorders, successful treatment of the anxiety disorder results in at least partial “normalization” of personality traits.

Using the data from the CLPS, Shea and colleagues found that borderline personality disorder patients whose panic disorder was unremitting were less likely to remit from borderline personality disorder (Shea et al., 2004). Marchesi and colleagues, in their 1-year prospective, controlled pharmacotherapy study of patients with panic disorder, found that, after treatment, the rate of comorbid personality disorder decreased from 60% to 43% (Marchesi, Cantoni, Fonto, Giannelli, & Maggini, 2005). This was mainly accounted for by the reduction in the rate of paranoid, avoidant, and dependent traits. In fact, a decrease in avoidant traits was observed only in patients who remitted from panic disorder.

It should be noted that the results of these studies do not necessarily indicate that personality changes with successful treatment result in a return to premorbid function. For example, it may be that pharmacologic and psychotherapeutic interventions have effects on personality traits themselves (p. 594) (presumably temporary, in the pharmacologic case) (Jorm, 1989; Knutson et al., 1998). Interestingly, although these patients' personalities normalize to some extent with successful treatment, there is some evidence that their personalities remain differentiable from normal controls (Reich, Noyes, Hirschfeld, Coryell, & ƠGorman, 1987). It is impossible to tell without truly prospective designs whether these differences from controls are “scar” effects of having had an episode of panic disorder.

Conclusion

Personality traits and most anxiety disorders are strongly related. Personality traits may be risk factors for anxiety disorders, consequences of anxiety disorders, or may share common underlying etiologies with anxiety disorders. Future work should further clarify causal relationships. Personality traits also appear to affect the clinical severity and prognosis of anxiety disorders, and vice versa.

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