Introduction
Depression is one of the most common psychological disorders that imposes many individual, social, and economic costs on people and society [1]. Since depression is a debilitating and often chronic and recurrent illness, it is essential to know the related factors and provide early intervention [2]. Some related factors are worry, cognitive inflexibility, and maladaptive cognitive emotion regulation (CER). The difficulty with CER plays an essential role in psychological vulnerability. The CER refers to the cognitive ability to manage and modify emotional reactions [3]. Another influential factor in the emergence of depression is the deficit in cognitive flexibility [4]. Cognitive flexibility is a construct of mindfulness intervention about different dimensions of mental health and acts as a fundamental aspect of mental health to achieve psychological health [5]. Worry, as another factor related to depression, can become a problem and cause significant interference in people's performance [6]. Since depression disrupts a person's daily and social activities, it can lead to helplessness and avoidance of social relations. People suffering from this disorder seek treatment solutions to reduce and eliminate the symptoms. [7]. One of these methods is dialectical behavior therapy (DBT) is a cognitive-behavioral approach that emphasizes the psychosocial aspects of therapy. This study aims to assess the effect of DBT on CER, cognitive flexibility, and worry in women with depressive disorder.

Methods
This is a randomized controlled clinical trial with a pre-test/post-test design. The study population includes all women with depression referred to the psychology clinics of Hami, Rahgosha, and Fardaye Behtar in Jahrom, Iran, in 2022. Of these, 30 women who scored 20-28 (moderate depression) in the Beck depression inventory (BDI) were selected using a purposive sampling method and randomly assigned two intervention (n=15) and control (n=15) groups. First, pre-test assessments were taken from both groups. Then, the intervention group underwent group DBT at 8 sessions. After the end of the intervention, post-test assessments were taken from both groups. The data collection tools included the cognitive emotion regulation questionnaire (CERQ) of Garnefski et al. [9], the cognitive flexibility inventory of Dennis and Vander Wal [10], the Penn State worry questionnaire of Meier et al. [8], and BDI [11]. 
The DBT protocol based on Linehan's biosocial theory, which was used in this study, has been prepared by Alijanzadeh et al. [12]. The collected data were analyzed in SPSS software, version 24 using descriptive (Mean±SD) and inferential (multivariate analysis of covariance) statistics. Before conducting the analysis of covariance, the Kolmogorov-Smirnov test was used to assess the normality of data distribution, Box's M to assess the homogeneity of variance-covariance matrices, and Levene's test to assess the equality of variances 

Results
The patients' mean age and educational level were not significantly different between the two groups. Their mean in the control and experimental groups were 26.93±1.83 and 26.73±1.53, respectively. The results in Table 1 showed that the DBT had a significant effect on the study variables; adaptive strategies of CER and cognitive flexibility increased after intervention, while maladaptive strategies of CER and worry significantly decreased.



Conclusion
Dialectical behavior therapy can increase adaptive CER strategies and cognitive flexibility of women with depression. It can also reduce depressive women’s maladaptive CER strategies and worry. More research is recommended in other centers and cities of Iran. It is recommended to compare the effectiveness of DBT with other cognitive-behavioral therapies and drug treatments in future studies.

Ethical Considerations
Compliance with ethical guidelines
This study has ethical approval from the ethics committee of Birjand University of Medical Sciences (Code: IR.BUMS.REC.1401.265). All participants signed an informed consent form to participate in the research. This study was registered by the Iranian Registry of Clinical Trials (IRCT) (ID: IRCT 20230517058212N1).

Funding
This study was extracted from the PhD dissertation of Zohre Jafarzade Jahromi approved by Department of Clinical Psychology, the Islamic Azad University, Birjand Branch. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Authors contributions
Conceptualization, study design and supervision: Zohre Jafarzade Jahromi and Abdol Majid Bahrainian; Data collection, data analysis and initial draft preparation: Zohre Jafarzade Jahromi; Statistical analyses: Fatemeh Shahabizadeh; Final approval: All authors.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgements
The authors would like to thank all participants and psychologists for their cooperation in this study. 


 

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