Avoidant personality disorder in individuals with generalized social anxiety disorder: What does it add?

Abstract

Avoidant personality disorder (AvPD) has a high level of symptom overlap and comorbidity with generalized social anxiety disorder (GSAD). We examined whether the presence of comorbid AvPD adds significant clinically relevant information for individuals seeking treatment for GSAD. Results suggested that AvPD was significantly associated with poorer quality of life and greater disability in univariate, but not multivariate analyses. Endorsement of more AvPD symptoms was associated with increased disability, increased risk of intimacy, and lower social support, even after covariate adjustment. Specifically, AvPD item 3, hard to be “open” even with people you are close to, was most strongly correlated with quality of life and disability. A binary diagnosis of AvPD alone adds little beyond a marker of greater GSAD severity and depression among patients with GSAD, while a specific feature of AvPD not captured by the GSAD diagnosis, namely emotional guardedness, may be associated with greater impairment.

Introduction

In the past decade, the clinical utility of the diagnosis of avoidant personality disorder (AvPD) in the presence of a comorbid diagnosis of generalized social anxiety disorder (GSAD; e.g., Chambless et al., 2008, Cox et al., 2009, Hummelen et al., 2007) has been debated. GSAD is an Axis I diagnosis in the DSM-IV (American Psychiatric Association, 2000), and is characterized by persistent fear of embarrassment in most social and performance situations and recognition that this fear is unreasonable. Individuals with GSAD either avoid these situations or endure them with extreme anxiety. In contrast, AvPD is an Axis II personality disorder, characterized by avoidance of social situations and fear of negative evaluation, described as “a pervasive pattern of social inhibition, feelings of inadequacy, and hypersensitivity to negative evaluation” (American Psychiatric Association, 2000). Previous studies have found a high prevalence of AvPD among individuals with GSAD, with estimates ranging from 25 to 89% (Chambless et al., 2008, Cox et al., 2009, van Velzen et al., 2000). Similarly, high rates of GSAD have been reported among those with AvPD (36–100%; Cox et al., 2009, Herbert et al., 1992, Holt et al., 1992).

Given the high degree of overlap between these two diagnoses, theorists have posited that AvPD and GSAD may not be distinct conditions. Rather, they might reflect a single construct that exists on a continuum, with AvPD representing a more severe manifestation of GSAD (e.g., the severity continuum hypothesis; van Velzen et al., 2000). Specifically, if GSAD and AvPD reflect a single construct, then there is no clinical utility in additionally diagnosing AvPD in individuals with GSAD, and the current diagnostic system should be revised. Indeed, proponents of the severity continuum hypothesis have called for major revisions to the AvPD and GSAD diagnostic criteria (Reich, 2000) or for combining the two disorders into one in the DSM (Ralevski et al., 2005).

The severity continuum hypothesis rests on the suppositions that (1) individuals with GSAD and AvPD exhibit more severe symptoms and greater impairment than those with GSAD without AvPD, and that (2) the greater severity observed in AvPD compared to GSAD can be entirely accounted for by differences between the two groups in overall GSAD symptom severity. To affirm the severity continuum hypothesis, researchers would need to demonstrate clear evidence in support of both of the aforementioned points. However, a clear refutation of the severity continuum hypothesis is more difficult, because even if researchers were able to demonstrate that differences between AvPD and GSAD persist after controlling for symptom severity, the possibility that the differences are due to interactions on the higher end of the severity continuum remains. Thus, the question of potential interactions would also need to be addressed to successfully refute the severity continuum hypothesis. Furthermore, even if differences persist after controlling for symptom severity and potential interactions, questions would remain as to whether such differences were clinically significant and warrant the inclusion of separate GSAD and AvPD diagnoses in the DSM.

Evidence in support of the first tenet of the severity continuum hypothesis comes from several studies demonstrating that individuals with comorbid GSAD and AvPD exhibit more severe social anxiety symptoms (Chambless et al., 2008, Cox et al., 2009, van Velzen et al., 2000) and higher rates of psychiatric comorbidity (Boone et al., 1999, Cox et al., 2009, Herbert et al., 1992, Holt et al., 1992) than those with GSAD only. However, only two studies (Chambless et al., 2008, Cox et al., 2009) have addressed the second tenet of the severity continuum hypothesis by examining whether differences between GSAD with and without AvPD persist after controlling for GSAD symptom severity, and these studies have produced mixed results. Chambless and colleagues (2008) found no significant differences between GSAD–AvPD and GSAD-alone in social skills after controlling for GSAD symptom severity. However, they did find lower levels of self-esteem among individuals with comorbid AvPD after controlling for GSAD symptom severity. Similarly, Cox and colleagues (2009) found that the likelihood of receiving a diagnosis of AvPD increased with GSAD symptom severity, but also found higher rates of mood, anxiety, and substance use disorder comorbidity and lower mental health-related quality of life among GSAD individuals with comorbid AvPD relative to those with GSAD-alone. In contrast to the findings from Chambless et al., these differences all remained after controlling for GSAD symptom severity. However, the majority (60.5%) of those with AvPD in their sample did not meet criteria for GSAD. Although the available data are mixed as to whether the presence of diagnosed AvPD adds additional information regarding symptomatology, comorbidity, and quality of life beyond that associated with greater severity of social anxiety in general, taken together they suggest that it is unlikely that AvPD can be explained as simply a more severe variant of GSAD; of note, however, the majority of studies examining the overlap between AvPD and GSAD did not control for GSAD symptom severity in their analyses. Further, neither of the two studies that controlled for symptom severity employed a validated, clinician-rated measure of GSAD severity.

In the present study, we sought to address these limitations. Specifically, we investigated the impact of comorbid AvPD on quality of life (QOL), disability, and interpersonal functioning among a large sample of individuals with a primary DSM-IV diagnosis of GSAD as determined by trained clinicians with semi-structured diagnostic interviews. First, we examined whether individuals with and without a diagnosis of AvPD differed on these psychosocial variables and whether any observed differences could be fully explained by differences in GSAD symptom severity. Second, we examined whether AvPD considered as a continuum, based on the number of AvPD symptoms endorsed, was uniquely associated with these quality of life and function measures. Finally, we examined the association between each AvPD symptom and baseline QOL, disability, and functioning, in order to better understand which specific aspects of AvPD may contribute to differences between patients with GSAD with or without comorbid AvPD. Specifically, based on previous work suggesting that AvPD is associated with more severe social phobia symptom severity, we hypothesized that Liebowitz Social Anxiety Scale (LSAS) scores would be higher among the AvPD–GSAD group compared to the GSAD alone group. We also hypothesized that demographics, presence of major depressive disorder (MDD), and GSAD symptom severity would wholly account for any differences between the AvPD–GSAD and GSAD alone groups on the psychosocial measures in the first model (when AvPD was conceptualized as a dichotomous variable) but not in the second model (when AvPD was conceptualized as an ordinal variable).