The Interface of Personality Traits and Anxiety Disorders

O. Joseph Bienvenu, MD, PhD, and Mina Brandes, MD

Dr. Bienvenu is assistant professor in the Department of Psychiatry and Behavioral Sciences at the Johns Hopkins School of Medicine in Baltimore, Maryland.

Dr. Brandes is resident in the Department of Psychiatry and Behavioral Sciences at the Johns Hopkins School of Medicine.

Disclosure: The authors do not have any affiliations or financial interests in a commercial organization that might pose a conflict of interest.

Funding/support: This work was supported by a grant from the National Institute of Mental Health (grant no. K23 MH64543) awarded to Dr. Bienvenu.

Please direct all correspondence to: O. Joseph Bienvenu, MD, PhD, 600 N Wolfe St, Meyer 101, Baltimore, MD 21287; Tel: 410-614-9063; Fax: 410-614-5913; E-mail: [email protected].

Abstract

Anxiety disorders are strongly related to normally distributed personality traits such as neuroticism, as well as personality disorder traits (avoidant and dependent traits in particular). This article presents a heuristic tool for physicians to consider how personality traits may relate etiologically to anxiety disorders as risk factors, complications, and results of common underlying etiologies. Current evidence suggests that high neuroticism (a general tendency to experience negative emotions) frequently precedes the onset of anxiety disorders, but it is unclear whether this trait is itself a risk factor for anxiety disorders or is purely a result of genetic factors that also influence risk for anxiety disorders. Also, there is some evidence that it is difficult to get an accurate sense of a person’s long-term personality traits during the acute phase of an anxiety disorder (at least panic disorder); that is, acute states may exaggerate a patient’s personality vulnerabilities. Nevertheless, clinicians should consider high neuroticism and avoidant and dependent traits at least as markers of risk for initial and comorbid anxiety (and depressive) disorders. The article also discusses the gross overgeneralized claim that extremes of all personality traits associated with anxiety disorders adversely affect their response to treatment.

Introduction

Anxiety disorders are very common illnesses that place a substantial burden on patients, their families, and society.^1,2 This article presents a heuristic tool for physicians to consider how personality traits may relate to the etiology, treatment, and prognosis of anxiety disorders.

It is important to note that it is likely that the next version of the Diagnostic and Statistical Manual of Mental Disorders will revise the conception of clinically relevant personality traits. One likely change will be a shift toward thinking of personality in dimensional (ie, less versus more of a trait) rather than categorical (ie, present or absent) terms. At issue is which personality dimensions to include in the nomenclature.

Two personality dimensions that appear in most conceptions of personality and seem particularly relevant to the anxiety disorders are neuroticism and extraversion. Neuroticism refers to one’s tendency to experience negative emotions and cope poorly. Persons high in neuroticism tend feel 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 one’s quantity and intensity of interpersonal interactions and positive emotions. Persons high in extraversion tend to be warm, gregarious, assertive, active, excitement-seeking, and emotionally bright compared to more introverted persons. Neuroticism and extraversion are so-called “normal” or “general” personality traits; they are normally distributed in the population, like height or intelligence. Neuroticism and extraversion are also relatively orthogonal or independent of one another; one can be high in neuroticism and extraversion, high in one but not the other, or low in both.

Consider the Figure, which shows the distribution of neuroticism and extraversion factor scores in persons with and without lifetime anxiety disorders in the general population of east Baltimore.^3,4 Here, personality scores are standardized to a separate general population sample using a t-score, with a mean of 50 and standard deviation of 10.⁵ First, note that although this group was oversampled for psychopathology,⁶ neuroticism and extraversion are fairly normally distributed. Next, note that persons with simple (or specific) phobia have neuroticism and extraversion scores that are distributed much like those of the rest of the sample, though simple phobics tend to be slightly higher in neuroticism and lower in extraversion. In contrast, persons with social phobia and agoraphobia tend to be high in neuroticism, introverted, or both. Finally, persons with panic disorder, obsessive-compulsive disorder (OCD), or generalized anxiety disorder (GAD) tend to be high in neuroticism only. In each case, however, there are exceptions: for example, there are social phobics who are extraverted and low in neuroticism. Nevertheless, it is clear that there are strong relationships between these personality traits and anxiety disorders; these relationships have been demonstrated repeatedly in clinical and nonclinical samples.⁷ Note that high neuroticism has also been consistently related to depressive disorders and the comorbidity among anxiety and depressive disorders.^8,9

In terms of personality disorder traits, symptoms of all of the major personality disorder groupings (ie, odd, dramatic, and anxious clusters) have been noted in higher than expected numbers in patients with anxiety disorders. However, anxious cluster personality traits (ie, avoidant, dependent, and to a lesser extent obsessive-compulsive) appear particularly common in patients with anxiety disorders, though schizotypal and borderline traits are also fairly common.⁷ A recent general population study showed that avoidant and dependent traits are particularly common in persons with anxiety or depressive disorders.¹⁰ It is worth keeping in mind how personality disorder traits and “normal” personality traits are related. Specifically, borderline and dependent traits correlate strongly with neuroticism, while avoidant traits correlate strongly with both neuroticism and introversion. Schizotypal traits also correlate relatively strongly with neuroticism and introversion.¹¹

The important question is, how are personality traits and anxiety disorders related? Are extremes of personality traits risk factors for anxiety disorders, just as hypertension, for example, is a risk factor for coronary artery disease? Is personality measurement affected by the state of having an anxiety disorder (though personality is relatively stable in adulthood¹²)? Are personality traits shaped by the experience of having (or having had) an anxiety disorder? Are personality traits and anxiety disorders manifestations of the same underlying causes? Finally, do personality traits affect the prognosis of anxiety disorders? This article weighs the strength of research evidence in support of these considerations (see the Table for a brief overview) and discusses the implications they have for clinical practice.

Is There Evidence That Personality Traits Act as Risk Factors?

Whether personality traits act as rsk factors for disorders can be addressed by examining personality traits and anxiety disorders longitudinally. There are actually only a few such longitudinal studies, since these studies are rather expensive and difficult to conduct. Angst and Vollrath,¹³ for example, measured personality traits in young male military recruits and followed these men for 17 years. High baseline neuroticism predicted incidence of anxiety neurosis (now called panic disorder and GAD) over the follow-up period.¹³

Krueger¹⁴ examined 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; unfortunately, there was limited power to examine individual anxiety disorders.¹⁴

Bramsen and colleagues¹⁵ 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. “Psychoneuroticism” was a very strong predictor of onset of posttraumatic stress disorder (PTSD) symptoms, second only to traumatic event exposure.¹⁵

Finally, Fauerbach and colleagues¹⁶ 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.¹⁶

Regarding personality disorder traits, recent data culled from the Children in the Community Study by Johnson and colleagues¹⁷ showed that adolescent personality disorders from all clusters predicted onset of anxiety disorders by young adulthood when controlling for adolescent Axis-I disorders.¹⁷ This was a population-based study, and the authors apparently did not have sufficient power to focus on individual personality disorders and anxiety disorders.

These studies show that personality traits prospectively predict the onset of anxiety disorders; however, despite the title of this section, 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 trait levels are, in some cases, prodromal symptoms of anxiety disorders.

Is Personality Assessment Affected by Anxiety States?

Although anxiety disorders are sometimes trait-like (ie, they resemble personality constructs in being relatively life long, such as in many patients with GAD or generalized social phobia), in some cases anxiety disorder onsets are disease-like. For example, spontaneous panic attacks appear to herald the onset of a condition with relatively clear boundaries in some patients (ie, there is a fairly well-defined break in mental life for these patients). Therefore, in conditions like panic disorder, it is certainly reasonable to ask whether personality traits, as assessed after onset, really reflect a person’s premorbid characteristics. Truly prospective studies on this topic have not been performed thus far (ie, with personality measured before and after onset, as well as after recovery). However, several studies have shown changes (toward normal) in personality traits in patients with panic disorder and agoraphobia after successful treatment.^18,19 Therefore, clinicians should consider the possibility of some degree of state-trait confounding in acutely anxious patients with panic disorder. However, 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 (presumably temporary, in the pharmacologic case).^20,21 Interestingly, although these patients’ personalities normalize to some extent with successful treatment, their personalities remain differentiable from normal controls.^22,23 It is impossible to tell without truly prospective designs whether or not these differences from controls are “scar” effects of having had an episode of panic disorder, which is discussed in further detail in the next section.

Are Personality Traits Shaped by the Experience of Having an Anxiety Disorder?

It is a commonly held belief that personality is still being formed during childhood, adolescence, and perhaps young adulthood. Therefore, the results of the following recent studies are of great interest. Lewinsohn and colleagues²⁴ followed subjects recruited from representative schools in western Oregon for a depression study. The authors found that adolescent anxiety disorders predicted schizotypal, schizoid, borderline, avoidant, and dependent personality traits in early adulthood, controlling for other adolescent Axis-I disorders. Unfortunately, Lewinsohn and colleagues²⁴ did not assess the possibility that these personality traits might have already been present in adolescence. Kasen and colleagues²⁵ took this area of research a step further in similar analyses of data from the Children in the Community Study. They found that adolescent anxiety disorders predicted Cluster A (“anxious cluster”) and Cluster C (“odd cluster”) personality disorders in young adulthood (when controlling for adolescent personality disorders and several other potentially relevant variables).²⁵

Thus, it may be that personality traits are shaped by the experience of having (or having had) an anxiety disorder, at least in adolescence. However, the caveat about possible common underlying etiologies still holds, in this case with personality traits being the later manifestations.

Are Personality Traits and Anxiety Disorders Due to Common Underlying Causes?

In the last 20 years, researchers have begun to examine whether genetic factors may help explain why personality traits are so strongly related to anxiety disorders. For example, Jardine and colleagues²⁶ used an Australian twin sample to find that genetic variation in symptoms of anxiety was largely dependent on the same factors that affected the neuroticism trait. More recently, Hettema and colleagues,²⁷ also using twin data, found that genetic factors that influence both neuroticism and risk for GAD explained most of the observed phenotypic overlap between these characteristics.

Family studies suggest that personality traits 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’²⁸ “behavioral inhibition to the unfamiliar.” Behaviorally inhibited children are cautious, quiet, introverted, and shy in unfamiliar situations.

Rosenbaum and colleagues²⁹ have also 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 to control children, the former group had higher rates of familial anxiety disorders.²⁹

Similarly, Reich³⁰ found that avoidant and dependent personality traits were more common in first-degree relatives of patients with panic disorder compared to relatives of controls. Also, Samuels and colleagues³¹ found that obsessive-compulsive personality traits and neuroticism were elevated in first-degree relatives of patients with OCD compared to relatives of controls.

Finally, Stein and colleagues³² found that trait anxiety and harm avoidance (related to both neuroticism and introversion^33,34) were elevated in relatives of probands with generalized social phobia, compared to relatives of control probands. A caveat when considering family study results is that these designs do not differentiate genetic and common (within-family) environmental factors.

Ultimately, it would be useful to determine whether or not inherited personality traits are themselves risk factors for anxiety disorders, or whether personality traits are simply part of an inherited spectrum that includes anxiety disorders (ie, personality traits and anxiety disorders may or may not have direct effects upon one another, but simply be manifestations of the same underlying causes). No such studies on this have been conducted so far, although genetically informative longitudinal studies could address this issue (eg, twin studies).⁷

Do Personality Traits Affect the Prognosis of Anxiety Disorders?

Personality disorder traits and high neuroticism have often been noted to predict worse treatment outcomes and more functional impairment in patients with Axis-I conditions.^35-37 In a recent naturalistic study,³⁸ avoidant personality disorder predicted a 34% lower likelihood of remission from GAD and a 41% lower likelihood of remission from social phobia (dependent personality disorder also predicted a lower likelihood of remission from GAD).³⁸ However, as noted by Dreessen and Arntz,³⁹ 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. Nevertheless, patients with OCD and substantial schizotypal personality traits frequently seem to have poorer responses to treatment, as do patients with panic disorder and substantial avoidant personality traits.³⁹ 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.^40,41 It is worth mentioning that, while schizotypal personality disorder may not be particularly common among patients with OCD,^31,42 its relationship to poor treatment outcome is fairly consistent. Results of a recent study by Moritz and colleagues⁴³ suggest that it may be the so-called positive schizotypal symptoms (eg, unusual perceptual experiences) that predict failure of traditional treatments (eg, serotonin reuptake inhibitors and behavioral therapy). These positive symptoms appear discontinuous from the “normal” personality traits considered here, unlike the avoidant and dependent (and to a lesser extent obsessive-compulsive) personality traits that are so common among persons with anxiety disorders. As Moritz and colleagues⁴³ suggest, patients with positive schizotypal symptoms and OCD may respond better to low-dose atypical neuroleptics and specifically tailored behavioral interventions. These treatments are perhaps best left to specialists, when possible.

Conclusion

Anxiety disorders are strongly related to normally distributed personality traits, such as neuroticism, as well as personality disorder traits (avoidant and dependent in particular). Current evidence suggests that high neuroticism often precedes onset of anxiety disorders, but it is unclear whether this trait is itself a risk factor for anxiety disorders or purely a result of genetic factors that also influence risk for anxiety disorders. Also, there is some evidence that it is difficult to get an accurate sense of a person’s long-term personality traits during the acute phase of an anxiety disorder (at least panic disorder); that is, acute states may exaggerate a patient’s personality vulnerabilities. Nevertheless, clinicians should consider high neuroticism and avoidant and dependent traits as, at least, markers of risk for initial and comorbid anxiety (and depressive) disorders. It would be a gross overgeneralization to say that extremes of all personality traits associated with anxiety disorders adversely affect their response to treatment, though patients with particular combinations of personality traits and anxiety disorders may have better outcomes in specialist care. PP

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