Extended Abstract

Introducrtion
Irritable Bowel Syndrome (IBS) is among the most common functional gastrointestinal disorders, marked by abdominal pain or spasms, altered bowel habits, bloating, and digestive discomfort in the absence of any identifiable structural or biochemical abnormality (Chey et al., 2015). Alongside physical symptoms, this condition is linked to various psychological difficulties, such as anxiety, worry, and emotional dysregulation (Abdelaziz et al., 2023; Owyang, 2022). Arnsten (2009) suggests that stress and emotional reactivity may contribute to the onset and persistence of IBS symptoms through heightened allostatic load and physiological alterations. Moreover, adolescents with IBS show a greater tendency to experience anxiety symptoms and related cognitive impairments.
Anxious thoughts, a central cognitive component of anxiety, involve persistent and uncontrollable concerns about potential threats or negative outcomes that can disrupt cognitive functioning (Stout et al., 2015). Mental disorders such as anxiety and depression have been found to increase the prevalence of psychosomatic conditions, and their co-occurrence tends to worsen the severity of psychosomatic symptoms (Tatayeva et al., 2022). Cognitive flexibility, by contrast, refers to an individual's awareness of available options in any situation, willingness to adapt and change across circumstances, belief in their capacity to adjust effectively, and sense of agency in choosing how to act (Martin & Rubin, 1995). Studies have shown that lower cognitive flexibility is associated with greater vulnerability to a range of mental health problems, including depression, anxiety, psychosomatic issues, and general psychological distress (Martin & Rubin, 1995; Masuda & Tully, 2012).
Transdiagnostic unified treatment, which targets the shared processes underlying emotional disorders, is a third-wave cognitive-behavioral approach that may effectively address psychological difficulties in adolescents. This approach involves reshaping emotional responses, enhancing emotional awareness, fostering flexible thinking, and decreasing maladaptive strategies (Ehrenreich-May et al., 2017). The present study aimed to investigate the effect of unified transdiagnostic treatment on anxious thoughts and cognitive flexibility in adolescent girls with symptoms of IBS.

Method
The present study employed a quasi-experimental method with a pretest-posttest design including a control group. The statistical population consisted of all female adolescents exhibiting symptoms of irritable bowel syndrome (IBS) in public secondary schools in Zahedan during the 2023–2024 academic year. Participants were selected through non-random purposive sampling based on the established inclusion criteria. Initially, among students displaying IBS symptoms, eligible individuals were identified using two instruments: the Irritable Bowel Syndrome Questionnaire, based on Rome IV criteria, and the Irritable Bowel Syndrome Severity Scoring System (IBS-SSS). Ultimately, 32 adolescent girls were assigned to two groups—an experimental group and a control group—each comprising 16 participants. The experimental group received the Unified Protocol for Transdiagnostic Treatment (Ehrenreich-May et al., 2017) across 14 weekly 90-minute sessions. The research instruments included the Wells Anxiety Thought Inventory (Wells, 1994) and the Cognitive Flexibility Inventory (Dennis & Vander Wal, 2010). Data were analyzed using multivariate analysis of covariance (MANCOVA) via SPSS version 27.
Findings
To examine the assumptions of multivariate analysis of covariance (MANCOVA), the Kolmogorov-Smirnov test was conducted, along with tests for homogeneity of regression slopes, Levene's test, and Box's M test. The results indicated that the data distribution was normal, regression slopes were homogeneous, and covariance matrices were equal. Although the assumption of homogeneity of variances was violated for the health anxiety subscale, the analysis of covariance proved robust to this violation given the equal group sizes. The assumptions required for MANCOVA were therefore confirmed, and the Wilks' Lambda test showed a significant effect of group on the dependent variables (anxious thoughts and cognitive flexibility) (P < 0.001). Furthermore, MANCOVA results indicated that, after controlling for pretest effects, significant differences emerged between the two groups in the subscales of metaworry (P < 0.001, η² = 0.67), social anxiety (P < 0.001, η² = 0.64), and health anxiety (P < 0.001, η² = 0.73). Regarding cognitive flexibility, analysis of covariance showed that, after controlling for pretest scores, group differences were significant for the alternatives (P < 0.001, η² = 0.72) and control (P < 0.001, η² = 0.78) subscales; however, no significant difference was found for the alternatives to human behaviors subscale (P = 0.53). Overall, the findings indicated that unified transdiagnostic treatment reduced anxious thoughts and improved certain components of cognitive flexibility among adolescent girls with symptoms of irritable bowel syndrome.

Disscusion
The first finding of the study demonstrated that unified transdiagnostic treatment led to a substantial reduction in anxious thoughts among adolescent girls with symptoms of irritable bowel syndrome. This finding is consistent with the results of studies by Shahkaram et al. (2024), Sadeghi Hafshejani et al. (2025), and Sharafi et al. (2023). This effectiveness can be attributed to training in emotional acceptance, reducing avoidance behaviors, confronting emotional experiences, and modifying dysfunctional cognitive patterns (Ehrenreich-May et al., 2017). Accordingly, this approach may help alleviate anxious thoughts in adolescents with symptoms of irritable bowel syndrome. The second finding indicated that unified transdiagnostic treatment had a positive effect on two components of cognitive flexibility—namely, alternatives and control. However, no significant effect was observed for the alternatives to human behaviors component. This finding aligns with the results of Rahimi et al. (2023) and Schaeuffele et al. (2022). This improvement is likely due to enhanced cognitive revision, problem-solving, and the ability to evaluate situations from multiple perspectives. Therefore, mental health therapists can use the unified transdiagnostic protocol as an effective approach for reducing anxious thoughts and improving cognitive flexibility in adolescents.