Introduction
Suicidal ideation is defined as thoughts of self-harm or killing oneself. It is an important indicator for assessing the risk of suicide, which can range from short-term thoughts to active planning for suicide and from vague ideas about ending life to very concrete plans. Studies have reported a suicide rate of 9.9 per 100,000 people in Iran. This rate is about 10% among adolescents. Nock et al. (2008), in a study in 17 countries, found that suicidal ideation reachs its peak level in adolescence and adulthood. In Saqqez County, located in Iran, according to the available statistics, there were 256 suicide attempts (15 led to death) in 2018, 288 suicide attempts (20 led to death) in 2019, and 211 suicide attempts (30 led to death) in 2020. These statistics for adolescents aged 15-18 were 58 cases in 2018, 50 cases in 2019, and 53 cases in 2020. In total, 17.43-25.12% of the suicide attempts during these three years were related to the age group of 15-18 years [1-12]. Adolescents with a history of suicide are less likely to predict adverse outcomes than adolescents with no history of suicide, and negative outcomes with lower degrees seem to affect decision-making ability [25]. Poor problem-solving ability is considered one of the important components of suicidal behaviors; Inadequacy in problem-solving can lead to suicide attempts [33]. Inner speech is a cognitive process that has been examined in studies on executive functioning in children and adults. Inner speech is associated with verbal working memory (through mental review), planning, inhibition, and cognitive flexibility [37-39]. Despite theoretical and empirical advances in inner speech, there is little evidence about the relationship between inner speech and suicidal ideation. This study aims to provide a structural model of the relationship of decision-making and stress coping styles with ​​suicide ideation, considering the mediating role of inner speech, among high school students in Saqqez Country, Iran 

Method
This is a descriptive-correlational study conducted in 2020-2021 using structural equation modeling (SEM). Considering that a sample size of more than 200 has been recommended for structural equation modeling, in this study, 423 high school students in Saqqez Country were selected using multi-stage cluster random sampling method. The data collection tools were (a) Scott and Bruce’s general decision making questionnaire (GDMS) with 25 items that measure five styles of rational, avoidant, dependent, intuitive, and spontaneous; (b) Lazarus and Folkman’s ways of coping questionnaire (WCQ) with 66 items measuring eight coping ways divided into two categories: problem-focused and emotion-focused; (c) The varieties of inner speech questionnaire - revised (VISQ-R) developed by Anderson-Day et al. with 26 items measuring five different factors of internal speech, dialogic, evaluative/critical, presence of other people, condensed ‌, and positive/regulatory; (d) Beck Scale for Suicide Ideation developed by Beck and Steer (1991) with 19 items and three subscales measuring the presence and intensity of suicidal thoughts. Pearson correlation test, multiple regression analysis, and SEM were used to test the research hypotheses in SPSS software, vesion 19.

Results
Participants were 423 high school students (270 girls and 153 boys). The results showed that 10.6% of the participants had suicide attempt at least once and 20.6% had suicidal thoughts. The GDMS components of avoidance and spontaneous; styles, the WCQ components of confrontive and escape-avoidance, and the VISQ-R components of evaluative/critical, presence of other people, and positive/regulatory were able to significantly predict suicidal ideation. Figure 1 shows the conceptual model of the study.



According to Table 1, the relationship of decision-making styles and stress coping styles with suicidal ideation was significant directly or after mediation by inner speech.



Conclusion
The results of the present study are consistent with the result of similar study conducted by Laghaei, Honarmand, and Arshadi, Zoodkhizi and Sedaghat, Qiu, Klonsky and May, and Onat et al. [9, 28, 47, 48, 50]. Regarding the relationship of coping styles with suicidal ideation, our results are consistent whit the results of the study of Rohani and Esmaeili, Qiu, and Chu et al. [3, 28, 51].
There were some limitations/disadvantages in this study. The high number of questions may cause the subjects to be tired which can affect their responses. The data were collected online (Shad application) and we had no direct supervision on their questionnaires. Moreover, the use of self-report tools and assessment of non-clinical groups, can affect the responses and the generalization of the results to clinical groups at risk of suicide.
The findings of this study can provides new insights about suicide in Iran. It is important to provide educational interventions about decision-making and stress coping styles to adolescents to act properly in stressful situations, and to react consciously to their inner speech.

Ethical Considerations

Compliance with ethical guidelines
This research has been approved by the ethics committee of Urmia University (Code: IR.URMIA.REC.1402.012).

Funding
This article was extracted from the doctoral thesis of Ebrahim Hosseini, approved by the Department of Psychology, Faculty of Literature and Human Sciences, Urmia University. This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Authors contributions
Writing: Ebrahim Hosseini; review & editing: Ali Esazadegan and Esmaeil Soleimani; final approval: All authors.

Conflicts of interest
The authors declared no conflict of interest.

Acknowledgments
The authors would like to thank all the personnel of the Education Organization and high schools in Saqqez County and all high school students participated in this study for their cooperation.