کنترل توجه در OCD و GAD: ویژگی ها و ارتباطات با علائم شناختی هسته ای

Abstract Obsessive–compulsive disorder (OCD) and generalized anxiety disorder (GAD) are both defined by excessive negatively-valenced cognitions. Although obsessional thoughts are considered essential to OCD and perseverative worry is considered essential to GAD, these excessive cognitions have been found to co-occur in both disorders. Accordingly, a common diathesis may influence the emergence of excessive thoughts in both disorders. The present study examined deficits in attentional control as a cognitive vulnerability that may contribute to both obsessional thought and perseverative worry. Patients with OCD (n = 30), GAD (n = 29), and non-clinical controls (NCC; n = 29) completed measures of obsessional thoughts, perseverative worry, and attentional control. Deficits in self-reported attentional control were found in both OCD and GAD relative to the NCC. However, attentional control was only related to excessive cognition in the GAD patient group, where deficits were associated with increased perseverative worry. Mediational modeling suggested that trait anxiety mediated the relationship between attentional control and perseverative worry in GAD. Implications of these findings for conceptualizing the role of attentional control in the genesis of excessive cognitions in OCD and GAD are discussed.

Results Group differences in attention control and excessive cognitions One-Way Analysis of Variance (ANOVA) revealed a main effect of group for the ACS Focus subscale [F (2, 85) = 14.51, p < .001] and the ACS Shift subscale [F (2, 85) = 13.26, p < .001]. As predicted, follow-up Tukey’s HSD tests revealed that compared to the control group, the OCD and GAD groups reported greater deficits in attentional focus and shifting (ps < .001). The two patient groups did not differ from each other in the severity of these deficits (p > .10). One-Way ANOVAs also revealed a main effect of group for the OCI-R Obsessing subscale [F (2, 85) = 58.35, p < .001], PSWQ [F (2, 85) = 65.53, p < .001], and RRQ Rumination subscale [F (2, 85) = 32.70, p < .001]. Follow-up Tukey’s HSD tests revealed that compared to the control group, the OCD and GAD groups reported more obsessional thoughts, perseverative worry, and rumination (ps < .001). Although the OCD group reported significantly more obsessional thoughts than the GAD group (p < .001), the two groups did not differ from each other in perseverative worry or rumination (ps > .10). Means and standard deviations for all measures are provided in Table 1. Table 1. Means and SDs for symptom measures. OCD GAD NCC N 30 29 29 ACS Shift 27.27 (5.23) 26.72 (4.70) 32.52 (4.22)a ACS Focus 20.07 (5.36) 20.48 (4.54) 26.00 (4.09)a OCI-R Obsessing 7.47 (3.34) 3.45 (2.49)b 0.52 (0.99)a PSWQ 61.83 (11.83) 62.00 (10.34) 35.48 (8.82)a RRQ Rumination 47.03 (8.90) 45.28 (7.78) 30.28 (9.36)a STAI-T 53.67 (10.41) 53.34 (10.24) 35.59 (8.88)a Note: means in the same row with different superscripts are significantly different (all ps < .001); OCD = obsessive–compulsive disorder; GAD = generalized anxiety disorder; NCC = non-clinical control; ACS Shift = Attentional Control Scale – Shifting subscale; ACS Focus = Attentional Control Scale – Focus subscale; OCI-R-Obsessing = Obsessive–Compulsive Inventory – Revised – Obsessing subscale; PSWQ = Penn State Worry Questionnaire; STAI-T = State Trait Anxiety Inventory—Trait Version, Form Y. Table options Association between cognitions and attention control Correlations between cognitive symptom measures and components of attentional control were examined within each group Table 2. Using the Bonferroni correction procedure for multiple comparisons, the familywise Type 1 error rate was set to .05 for each ACS subscale in each group. In the GAD group, both attentional focus and attentional shifting were specifically correlated with perseverative worry (Focus: r = −.54, p < .01; Shift: r = −.48, p < .01), in line with predictions. However, in the OCD group, the predicted correlations between deficits in components of attentional control and obsessional thoughts were not found; in patients with OCD, there were no significant correlations between components of attentional control and any type of excessive cognition(ps > .017). In the NCC group, the only significant correlation was between attentional focus and rumination (r = −.56, p < .01). Table 2. Correlations between attentional control and cognitive symptom measures. OCD GAD NCC ACS Focus ACS Shift ACS Focus ACS Shift ACS Focus ACS Shift OCI-R Obsessing −.10 .04 −.11 −.18 −.10 −.14 PSWQ −.20 .06 −.54* −.48* −.43 −.18 RRQ Rumination .05 −.01 −.28 −.31 −.56* −.25 Note: *p < .017; OCD = obsessive–compulsive disorder; GAD = generalized anxiety disorder; NCC = non-clinical control; ACS Shift = Attentional Control Scale – Shifting subscale; ACS Focus = Attentional Control Scale – Focus subscale; OCI-R-Obsessing = Obsessive–Compulsive Inventory – Revised – Obsessing subscale; PSWQ = Penn State Worry Questionnaire; RRQ Rumination = Rumination-Reflection Questionnaire – Rumination subscale. Table options Trait anxiety as a mediator in GAD Prior research suggests that the presence of trait anxiety may largely account for levels of worry and its maladaptive consequences (Mathews, 1990 and Olatunji et al., 2007). Accordingly, trait anxiety was examined as a mediator of the relationship between attentional control and perseverative worry in GAD, based on the recommendations of Baron and Kenny (1986). For this mediational analysis (depicted in Fig. 1), attentional control was assessed using the ACS total score. Evidence of mediation requires the following conditions to be present: (a) a significant relationship between trait anxiety and attentional control (r = −.57. p < .01), (b) a significant association between perseverative worry and attentional control (r = −.56. p < .01), (c) a significant relationship between trait anxiety and perseverative worry (r = .67. p < .01), and (d) the statistically significant relationship between perseverative worry and attentional control diminishes or disappears when trait anxiety is controlled. Pearson correlation coefficients indicated that conditions (a), (b), and (c) above were met. Condition (d), the critical test of mediation, was investigated by examining the magnitude of the relationship between attentional control and perseverative worry after controlling for trait anxiety. A two-step regression equation was estimated predicting perseverative worry with attentional control entered in the first step and trait anxiety in the second step as predictors. The key comparison involved the change in standardized regression coefficients for attentional control from step 1 (total effect) to step 2 (direct effect controlling for trait anxiety). The highly significant (p < .01) relationship between attentional control and perseverative worry became non-significant (p > .10) after controlling for trait anxiety. Moreover, trait anxiety emerged as a significant, unique predictor of perseverative worry. Thus, all a priori conditions were met, indicating that trait anxiety mediated the relationship between attentional control and perseverative worry. The significance of this mediated effect was statistically tested via the Sobel (1982) procedure, and the results of this test suggest that the effect of attentional control on perseverative worry is transmitted via trait anxiety (Sobel test of the significance of the indirect path: z = 2.31, p < .05). Complete results of these analyses are provided in Table 3. 1 Mediational model of the relations between attentional control, trait anxiety, ... Fig. 1. Mediational model of the relations between attentional control, trait anxiety, and perseverative worry in GAD. Note: **p < .01, ***p < .001; GAD = generalized anxiety disorder; ACS = Attentional Control Scale; STAI-T = State Trait Anxiety Inventory—Trait Version, Form Y; PSWQ = Penn State Worry Questionnaire. Figure options Table 3. Reductions in standardized regression coefficients for attentional control in the prediction of worry after controlling for trait anxiety in patients with GAD. Steps in regression Values Step 1 ΔR2 for ACS .31** β for ACS −.56** Step 2 ΔR2 for STAI-T .45** β for ACS controlling for STAI-T −.26 β for STAI-T .53** Overall R2 .50 F (2, 26) 12.74*** Note: **p < .01, ***p < .001; GAD = generalized anxiety disorder; ACS = Attentional Control Scale; STAI-T = State Trait Anxiety Inventory—Trait Version, Form Y.