In this series of studies, the nature of interpersonal functioning in GAD was examined and an interpersonal pathoplasticity model was applied. The pathoplasticity model suggests that individuals' personalities and Axis I disorders are largely independent, but affect one another's manifestation, course, and treatment. The current study results support the application of this model to GAD.
Four homogenous interpersonal subtypes were reliably derived in independent samples of individuals with GAD. The subtypes identified were the intrusive, exploitable, cold, and nonassertive groups. As evidence of the strength of the subtypes, high levels of interpersonal prototypicality and profile differentiation were found within identified clusters, indicating that each cluster exhibits a consistent dysfunctional interpersonal theme. When the GAD group was examined as a whole, low prototypicality and profile differentiation were found, indicating no consistent interpersonal theme and an underlying complexity of the data. The strong emergence of four clusters suggests that GAD, although categorized as a single Axis I entity in DSM-IV, has a significant amount of reliable, within-group variation in interpersonal functioning. As such, assumptions about the interpersonal functioning of individuals with GAD as a single unit may be at the cost of truly understanding people with this diagnosis.
The identification of these subtypes is noteworthy for its replication of those identified by Salzer and colleagues (2008)
in a German patient sample. However, as detailed earlier, the current study improves upon Salzer and colleagues (2008)
in a number of ways. In addition to solidifying the presence of the four interpersonal subtypes of GAD, the current series of studies also extends previous research by examining associations between interpersonal subtypes of GAD, attachment, and comorbid Axis II disorders. Consistent with theories of pathoplasticity, the four interpersonal subtypes did not differ in GAD severity (as indicated by the CSR). Furthermore, they did not differ on the HRSD and HARS. This supports one aspect of the pathoplasticity theory—namely that differences in interpersonal functioning across individuals with GAD cannot be accounted for by differences in Axis I symptoms.
As also expected, rates of Axis I comorbidity across the two studies were largely consistent across GAD subtypes, providing further evidence for independence of Axis I diagnoses and interpersonal functioning. However, one exception to this was found; there were no differences in Axis I comorbidity in Study 1 (other than a trend toward significance for social phobia), whereas in Study 2 there was a significant difference in rates of social phobia across interpersonal subtypes. Ninety percent of the nonassertive cluster met criteria for Social Phobia (as compared with 45.2% of the cold cluster, 38.9% of the exploitable cluster, and 28.6% of the intrusive cluster). This is probably due to the combination of larger rates of social phobia in study 2 (51.8% vs. 38.3% in study 1) as well as a much larger sample in Study 2. The exclusion of participants with panic disorder and severe major depression from study 1 and not from study 2 may also have impacted these results.
One possible explanation for differences between interpersonal subtypes in rates of social phobia in study 2 (and the trend toward significance in study 1) is that social phobia is a disorder for which the central features are about a particular type of interpersonal dysfunction. Symptoms of social phobia center around fear and avoidance of interacting with or being the focus of attention of other people. Also, individuals with social phobia tend to be nonassertive (Alden & Phillips, 1990
; Kashdan, McKnight, Richey, & Hofmann, 2009
). Further, two studies examining interpersonal pathoplasticity in social phobia found friendly-submissive clusters (Cain, et al., 2010
; Kachin, et al., 2001
). In both samples, the largest percentage of individuals fell in the nonassertive and submissive quadrants of the circumplex. In fact, Cain and colleagues (2009) found that all socially phobic outpatients reported interpersonal problems with nonassertiveness and submission. Therefore, it is not surprising that most individuals with social phobia in the current sample fell in the nonassertive cluster. Further examination of the effects of comorbidity of GAD and social phobia on interpersonal functioning appears warranted.
In contrast to the stability of rates of Axis I disorders which are theorized to be largely independent of interpersonal functioning in a pathoplasticity model, other aspects of functioning, are expected to vary between interpersonal subtypes, especially measures that are interpersonal in nature. Axis II disorders and attachment variables are two such measures of interpersonal functioning. Study 2 indicated that GAD subtypes did, in fact, differ in rates of Axis II diagnoses. For example, ninety-five percent of those in the nonassertive cluster met criteria for a personality disorder, as compared with 64.5% of the cold cluster, 64.3% of the intrusive cluster, and 47.1% of the exploitable cluster, providing support for the pathoplasticity model in GAD. Whereas avoidant personality disorder (AvPD) was the predominant personality disorder (75%), only 17.6% of the exploitable cluster, 16.1% of the cold cluster, and 14.3% of the intrusive cluster met criteria for AvPD. This suggests that the nonassertive cluster captured a selection of individuals with a tendency toward an Axis II diagnosis of AvPD, indicating again, that pathology in GAD varies by subtype. This is also consistent with Alden and Capreol's (1993)
finding that participants with AvPD scored very highly in non-assertive problems on the IIP-C.
Contrary to our hypotheses, there were no significant differences in attachment variables across interpersonal subtypes in either study, although there was a trend toward significance in study 2 with large effect sizes in both studies. It is possible that we did not have sufficient power for this difference to achieve significance. Previous research has demonstrated an association between attachment styles and specific IIP octants (Chen & Mallinckrodt, 2002
; Horowitz, et al., 1993
); however, no prior study had examined whether there were differences in attachment across IIP clusters. Instead, extant studies have examined correlations between scores on measures of attachment styles and various IIP octant scores. This method of scoring the IIP may not accurately represent samples in which there are subgroups of interpersonal clusters, such as those with GAD. Further, the attachment variables examined in the current study have not been examined in association with interpersonal problems and it is possible that these attachment variables may be associated with multiple interpersonal problems.
The current series of studies contribute to our understanding of the interplay between interpersonal behaviors and GAD and provide support for the application of the interpersonal pathoplasticity model to individuals with this diagnosis. We also extended existing research on GAD and interpersonal functioning; however, the results are subject to a number of limitations. One such limitation is the exclusion of individuals with substance use disorders. Although the pathoplasticity model would suggest that such comorbidity would not impact interpersonal subtypes, the exclusion of these individuals limits the generalizability of our findings. In addition, in order to examine whether our results would be consistent with a pathoplasticity model some of our predictions were in the direction of suggesting support for the null hypothesis. However, failing to reject the null hypothesis does not prove that the null hypothesis is true and therefore, findings supporting these predictions should be interpreted with caution. Another limitation of the current series of studies is the lack of ethnic and racial diversity in the samples. Given the association between culture and interpersonal dynamics, it is possible that different results would be identified in a more diverse sample. Further, because perceived racial stress, which is interpersonal in nature, is associated with worry (Rucker, West, & Roemer, 2010
) and individuals from diverse backgrounds worry about different topics than Caucasians (Scott, Eng, & Heimberg, 2002
), GAD symptoms and associated interpersonal styles may manifest differently in a more diverse sample. This study was also limited by the small number of individuals who met criteria for some comorbid Axis I and II disorders. Future research should examine larger samples with a greater number of individuals with various types of comorbid disorders, particularly Axis II.
An additional area for future exploration is related to treatment. Changes in some interpersonal problems have been associated with GAD symptom reduction in response to treatment (Borkovec, et al., 2002
; Crits-Christoph, Gibbons, Narducci, Schamberger, & Gallop, 2005
; Salzer, Pincus, Winkelbach, Leichsenring, & Leibing, in press
), and interpersonal problems change as a result of treatment for GAD (Borkovec, et al., 2002
; Crits-Christoph, Connolly, Azarian, Crits-Christoph, & Shappell, 1996
; Newman, et al., 2008
). However, the pathoplasticity model would predict that those with differing interpersonal styles would also have differential treatment outcome, because interpersonal problems and Axis I disorders affect one another's manifestation and course. Therefore, it may be that interpersonal problems change differentially as a result of various forms of therapy for GAD, such as cognitive-behavioral, interpersonal, and emotion-based approaches. If that is the case, then the assessment of interpersonal problems prior to the start of therapy may assist therapists in choosing the most appropriate therapeutic techniques to use. For example, in the case of clients with GAD who fall into the intrusive cluster, therapists may choose to discuss ways in which clients' worries may be related to their feelings of being responsible for solving others' problems. Cognitive-restructuring may be important to examine and alter schemata related to excessive responsibility for others. Therapists may also discuss the impact of clients' intrusive worrying and problem solving on others as this may affect clients' relationships. Further, therapists may encourage clients to learn appropriate coping skills to manage worries and regulate emotions independently, rather than divulging worries and other feelings to others. However, clients with GAD who fall into the nonassertive cluster may benefit more if therapists address worries about what may happen in their relationships if they are assertive or express their needs. Further, therapists may consider the importance of having clients set the agenda for therapy sessions, create homework assignments, or identify therapeutic goals to encourage them to be more assertive about their desires and to take a more dominant role in relationships. Such integrative therapy, combining CBT and interpersonal conceptualization and techniques, may provide a means of treating clients as a whole, rather than focusing primarily on symptoms or relationships (e.g., Newman, et al., in press
; Newman, et al., 2008
). Thus, the application of the pathoplasticity model to GAD may have large implications for improving therapy for the disorder by providing important information for treatment planning beyond DSM diagnosis.