Comparison of the Effectiveness of the Unified Protocol and Acceptance and Commitment Therapy on Cognitive Emotion Regulation and Ambiguity Tolerance in Patients with Generalized Anxiety Disorder

Abstract

This study aimed to compare the effectiveness of the Unified Protocol for Transdiagnostic Treatment and Acceptance and Commitment Therapy on cognitive emotion regulation and ambiguity tolerance in patients with generalized anxiety disorder. This quasi-experimental study used a pretest-posttest design with a two-month follow-up and a control group. The statistical population consisted of patients with generalized anxiety disorder attending psychological counseling centers and clinics in Tehran in 2026. Forty-five eligible patients were selected through convenience sampling and randomly assigned to three groups of 15 participants: Unified Protocol, Acceptance and Commitment Therapy, and control. Each intervention group received eight weekly 90-minute group sessions, while the control group remained on a waiting list. Data were collected using the Cognitive Emotion Regulation Questionnaire and the Multiple Stimulus Types Ambiguity Tolerance Scale-II. Mixed analysis of variance with repeated measures and Bonferroni-adjusted pairwise comparisons were used for data analysis. The time-by-group interaction was significant for adaptive cognitive emotion regulation strategies, F(4,84)=32.91, p<0.001, partial η²=0.610. A significant interaction was also found for maladaptive cognitive emotion regulation strategies, F(3.48,73.06)=36.52, p<0.001, partial η²=0.635, and for ambiguity tolerance, F(3.62,76.02)=29.87, p<0.001, partial η²=0.587. Bonferroni comparisons showed that both interventions significantly increased adaptive cognitive emotion regulation and ambiguity tolerance and significantly reduced maladaptive cognitive emotion regulation compared with the control group at posttest and follow-up. The Unified Protocol produced significantly greater improvements than Acceptance and Commitment Therapy across all three outcomes, and these differences remained significant at follow-up. Both the Unified Protocol and Acceptance and Commitment Therapy were effective in improving cognitive emotion regulation and ambiguity tolerance in patients with generalized anxiety disorder. However, the Unified Protocol demonstrated greater effectiveness across the assessed outcomes. These findings suggest that the Unified Protocol may be particularly useful for patients whose generalized anxiety is characterized by pronounced emotion dysregulation and low tolerance of ambiguity.