Introduction
The experience of war and various traumas can hurt individuals physically and psychologically. Studies have shown that war traumas have a negative impact on the psychological health of veterans [1]. One of the primary consequences of war in veterans is the post-traumatic stress disorder (PTSD) which can affect their family members, including wife or children [9]. The fathers’ PTSD can affect the emotional regulation strategies of children [14]. Emotional dysregulation is one of the most common problems in psychological disorders, including PTSD [15], which can lead to interpersonal problems in veterans with PTSD and their children [14]. Moreover, the parents’ PTSD can have a negative impact on the psychological flexibility of children [1, 10, 26]. Acceptance and commitment therapy (ACT), designed for psychological flexibility and avoidance, can be a suitable method for the integrative treatment of PTSD [30]. Studies has revealed that ACT can be helpful in reducing PTSD symptoms [31]. The present study aims to investigate the effect of ACT on emotional regulation, psychological flexibility, and symptoms in children of veterans with PTSD.

Methods
This is a randomized controlled clinical trial with a pre-test/post-test/follow-up design. Seventy participants were selected by simple random sampling method from among the children of veterans with PTSD (n=180) in Yazd, Iran. According to the inclusion criteria, 70 girls and boys aged 15-19 years were selected and randomly assigned into two groups of 35, including ACT and control. Afterwards, the group ACT was presented to the intervention group, while a 7-session life skills education program was presented to the control group. The data were collected at pre-test, post-test, and 12-month follow-up phases using the acceptance and action questionnaire – version 2 (AAQ-2), the difficulties in emotion regulation scale (DERS), and the PTSD Checklist for PCL. Then, all collected data were analyzed in SPSS software, version 22 using descriptive (Mean±SD) and inferential (ANOVA and ANCOVA) statistics. 

Results
During the treatment process, 5 children (two in the intervention group and three in the control group) left the study, and statistical analysis was carried out on the data of 65 children. In the intervention group, 20(60.6%) were males and 13(39.4%) were females. In the control group, 18(56.2%) were males and 14(43.8%) were females. The mean age of the subjects was 16.82 years in the intervention group and 16.65 years in the control group. In the intervention group, 13(39.4%) were studying in grade 10, 14(42.4%) in grade 11, 6(18.2) in grade 12. In the control group, one (3.1%) was in grade 9, 14(43.8%) in grade 10, 11(34.4%) in grade 11, and 8(18.8%) in grade 12.
It is noteworthy that 40 children received face-to-face intervention and 25 attended online intervention sessions. The number of participants in online and face-to-face sessions was the same in both groups, 5 in the intervention group and 5 in the control group,  and there were no statistically significant differences between the two groups in terms of the type of presentation, gender, age, and educational level (P>0.05). In other words, both groups were homogenous in terms of demographic factors (Table 1).


The results presented in Tables 2, 3, and 4 showed that the mean scores of DERS, AAQ-2, and total PTSD symptoms were significantly different between the ACT and control groups (P<0.01).






However, the groups were not significantly different in symptoms of re-experiencing trauma and negative alterations in mood and avoidance (P>0.05), the difference was significant in hyperarousal symptoms. The pre-test and post-test scores in the control group were significantly different in re-experiencing trauma (P<0.01). 

Conclusion
The results revealed that ACT improved emotional regulation skills and psychological flexibility of the children of veterans with PTSD. Furthermore, ACT alleviated the hyperarousal symptoms of these children, but it could not reduce negative alterations in mood, avoidance, or re-experiencing symptoms. 

Ethical Considerations
Compliance with ethical guidelines
This study has ethical approval from the Ethics Committee of Kashan University of Medical Sciences (Code: IR.KAUMS.REC.1400.018). The study was registered by the Iranian Registry of Clinical Trials (IRCT) (Code: IRCT 20210708051815N1)

Funding
This study was funded by Kashan University of Medical Sciences.

Authors contributions
Conceptualization: Amir Masoud Mirbagheri, Zahra Zanjani and Abdolah Omidi; Methodology, writing, Funding acquisition and resources: Zahra Zanjani and Amir Masoud Mirbagheri.

Conflicts of interest
The authors declared no conflict of interest. 

Acknowledgements
The authors would like to thank the Deputy for Research and Technology of Kashan University of Medical Sciences, and all participants for their support and cooperation in the present study.



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