(PS2-B36) Extraversion and Its Lower-order Facets Distinguish Major Depression from Generalized Anxiety Disorder

Background: Extraversion, a key dimension of temperament, is inversely related to depression (Klein et al., 2011). Although extraversion was long thought to be relatively specific to depression vis-à-vis anxiety (Brown & Barlow, 2009), a meta-analysis suggests that extraversion may be more attenuated in many forms of anxiety (Kotov et al., 2010). More definitive tests of specificity must take comorbidity into account and examine which lower-order facets of extraversion are driving these effects. Such analyses have been undertaken for social anxiety (Naragon-Gainey et al., 2009) but not yet for generalized anxiety disorder (GAD), the condition most closely related to major depressive disorder (MDD).

Method: Using the ADIS-5 (Brown & Barlow, 2014), 191 community-dwelling adults were diagnosed with comorbid MDD-GAD (n = 64), MDD-only (n = 34), GAD-only (n = 44), or no psychopathology (n = 49). All participants received clinical severity ratings (0–8) for MDD and GAD. Extraversion and its 6 facets were assessed using the NEO-PI-R (Costa & McCrae, 1992). We compared mean levels of extraversion and its facets across groups. We also correlated extraversion and its facets with MDD and GAD severity. To evaluate specificity, we tested for significant differences between correlations using Steiger’s t tests (Steiger, 1980), then followed up with partial correlations controlling for the opposing disorder’s severity.

Results: Extraversion differed significantly across all four groups (F = 24.60, p < .001): it was highest among healthy controls (M = 2.50, SD = .39) and progressively lower for GAD-only (M = 2.15, SD = .37), comorbid MDD-GAD (M = 1.93, SD = .52), and MDD-only (M = 1.72, SD = .46) groups. At the facet level, depressed participants had significantly lower warmth, gregariousness, assertiveness, activity, and positive emotions than GAD-only or control participants. MDD-only participants also had significantly lower activity and positive emotions than comorbid participants, and GAD-only participants had lower warmth, gregariousness, and positive emotions than controls. All clinical groups reported less excitement seeking than controls. Extraversion and its facets shared negative correlations with MDD severity (rs = -.51 to -.20) and GAD severity (rs = -.34 to -.12). Formal comparisons revealed that, except for excitement seeking, all correlations were larger for MDD than GAD severity, ts < 2.01, ps < .05. Additionally, extraversion’s correlation with MDD severity remained significant when controlling for GAD severity (r = -.43, p < .001); the opposite was not true for extraversion’s correlation with GAD severity (r= -.02, p </span>= .764). This pattern held for all facets (MDD rs = -.37 to -.15; GAD rs = -.12 to -.01).

Conclusion: Extraversion and its facets (except excitement seeking) were more strongly associated with MDD than GAD. Associations with MDD remained robust when controlling for GAD (but not vice versa), suggesting that MDD symptoms may be driving the GAD effects. Extraversion was lowest for those without comorbid GAD, suggesting that “pure” MDD cases may be most impaired. Given deficits in all 6 facets, interventions targeting interpersonal (e.g., warmth, gregariousness, assertiveness) as well as emotional deficits may be warranted.