An Evaluation of the Enhanced Cognitive-Behavioral Model of Bulimia Nervosa in Iranian Student Women

Reza Moloodi (  re.moloodi@uswr.ac.ir ) Substance Abuse and Dependence Research Center, University of Social Welfare and rehabilitation Sciences, Tehran, Iran. Maryam Mahmoodi Department of Cellular Molecular Nutrition, School of Nutritional Sciences and Dietetic, Tehran University of Medical Sciences, Tehran, Iran Zinat Mohammadpour Department of Cellular Molecular Nutrition, School of Nutritional Sciences and Dietetic, Tehran University of Medical Sciences, Tehran, Iran Farnush Naghashian Department of Cellular Molecular Nutrition, School of Nutritional Sciences and Dietetic, Tehran University of Medical Sciences, Tehran, Iran Haniye Alasti Department of Health psychology, Kharazmi University, Tehran, Iran Zahra babai Department of Clinical Psychology, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Zeinab Saleh Department of Clinical Psychology, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Paria Ahmadi Department of psychology, Faculty of psychology and social sciences, Islamic Azad University of Central Tehran Branch, Tehran, Iran. Masoumeh Barani Department of Clinical Psychology, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.


Introduction
Two decade researches demonstrated increasing prevalence of Eating Disorders (EDs) among women of Eastern societies (1)(2)(3)(4)(5) Thus, investigating the etiological and maintenance models of EDs in these cultures is an important research and clinical issue. and thereby binge eating and purging behaviors. According to the theory, patients with Bulimia Nervosa (BN) put their self-worth exclusively or largely on their weight and shape. This overvaluation of shape and weight is the core psychopathology of the BN. Therefore, the patients with BN engaged in dietary restraint or other weight control behaviors. However, perfect obey of these in exible dietary restraint rules is not possible and lead to binge eating episodes. The binge eating episodes, in turn, increases the concerns about weight and shape and thereby play a role in maintenance of dietary rules. Finally, concerns about weight and shape evokes compensatory behaviors after binge eating.
Fairburn et al., (7,8) extended the original CB-BN model in order to more fully speculate the factors involved in development and maintenance of EDs. The enhanced version of the model illustrates how low self -esteem, clinical perfectionism, interpersonal problems, and mood intolerance interact with the core psychopathology of EDs. In essence, low self-esteem and clinical perfectionism encourage person to duplicate her/his efforts to achieve expected goals about weight and shape. On the other hand, clinical perfectionism and low self-esteem lead to self-criticism after perceived failure. The enhanced version of the model outlines that in a subgroup of patients with EDs interpersonal problems may intensify selfesteem concerns and overvaluation of weight and shape, and elicit binge eating behaviors. Finally, the model proposed that some patients with EDs utilized binge eating and purging as a way of coping with overwhelming aversive mood state.
Consistent with the theory, prospective studies consistently demonstrated that appearance overvaluation and/or body dissatisfaction predict dietary restraint, eating disorder cognitions (9), EDs symptoms (10)(11)(12)(13), and binge eating behaviors (14). Also, dietary restraint has been indicated prospectively anticipate binge eating behaviors among women (15), adolescents (16), and children (17). One of these studies reported the predictive role of low self-esteem, and lower level of social support on eating symptomatology (14). Also, a number of path analytic studies tried to evaluate the original and enhanced version of CB-BN model. Studies using structural equation modelling or path analysis showed that original (18-20) and enhanced version of CB model of EDs t with the data. (18), (20) and (21) found that low self esteem predicted drive for thinness and/or body disatisfaction which, in tern, anticipated dietary restraint. Dietary restraint predicted binge eating and binge eating predicted purging behaviors. Four studies (19,22,23) evaluated the enhanced version of CB-BN model and found that low self esteem and clinical perfectionism associated with overvaluation of shape and weight which, in tern, prognosticate dietary restraint. Dietary restraint corelated with binge eating and benge eating predicted purging behaviors. Finaly, interpersonal problems anticipated dietary restraint and mood intolerance associated with binge eating and purging (19,22). However, to our konwledge, the CB-BN model has yet to be evaluated among women of Eastern socities. Thus, the current study aimed to investigate the validity of original and enhanced version of CB-BN model in a sample of Iranian student women. We tried to answer two questions: 1) Whether the original model of CB-BN model offer a valid representation of association btween overvaluation of shape and weight, dietary restraint, binge eating and purging among Iranian student women?
2) Dose the enhanced version of CB-BN model provide a good account of the relationship of low self esteem, clinical perfectionism, interpersonal problems, and mood intolerance with overvaluation of shape and weight, dietary restraint, binge eating and purging among Iranian student women?

Instruments
2.2.1. Eating Disorder Examination Questionnaire (EDE-Q 6.0) is a self report measure that assesses cognitive and behavioral aspects of EDs focusing on the last 28 days. The EDE-Q provides a global score and four subscales including restraint, shape concern, weight concern, and eating concern. The frequency of pathological eating behaviors (such as binge eating, laxative misuse) is evaluated through seven items. These items focus on the number of episodes that the behaviors occurred during the past 28 days. Psychometric properties of the Persian version of the EDE-Q have been demonstrated (24). (25) is 16 items self report measure and developed to assess the severity of binge eating in obese patients. Satisfactory sensitivity, speci city, and internal consitency of the Persian version of the BES was approved (24).

2.2.5.
Inventory of interpersonal problems-32 (IIP-32) is a self-report questionnaire that measures eight different domains of interpersonal behaviors. A number of studies reported satisfactory validity and reliability for IIP-32 (31,32). A study employing regression analysis showed two subscales from the IIP-32 (Hard to be Sociable and Too Dependent) accounted for unique variance in eating disorder symptoms (33). We used these two subscales in the current study as measures of interpersonal problems. The Hard to be Sociable subscale assesses di culty engaging in social relationships. The Too Dependent subscale re ects dependency on others for approval.
2.2.6. Rosenberg Self-esteem Scale (RSES) is a 10-item self-report instrument that assesses self-esteem on a four-point scale (1 = strongly disagree to 4 = strongly agree). The Persian version of the RSES has shown satisfactory reliability and validity (34,35). In the current study, the RSES demonstrated satisfactory internal consistency (0.86).

Procedure
Research assistants referred to the relevant classes at the universities and invited female students to participate in a study on eating behaviors among women. The research assistants provide information about the purpose and procedure of the study. Those who signed a written consent were asked to complete a battery of questionnaires. Ethical Committee of Tehran University of Medical Science approved the study procedure.

Statistical analysis
Descriptive statistics were used to report demographic information of the participants. We applied path analysis using AMOS 23. A preliminary analysis was performed to examine the validity of the measurement model using Con rmatory Factor Analysis (CFA). Following CFA analysis, the associations between variables were provided using Pearson correlation coe cient. After that, we tested both original and enhanced version of CB-BN model of EDs using path analysis on both goodness-of-t and parsimony to the data. We used x 2 /df, goodness-of-t index (GFI), adjusted goodness-of-t index (AGFI), incremental t index (IFI) and comparative t index (CFI) with values ≥ 0.90, and the root mean square error of approximation (RMSEA) with values ≤ 0.08 as goodness-of-t indices. We also used the Aikaike Information Criteria (AIC)(36) and Browne-Cudeck Criterion (BCC) (37), as measures of parsimony with lower values preferred.

Measurement Model
The independent CFA was performed to examine the measurement model of overvaluation of shape and weight, restraint eating, binge eating, purging, distress tolerance, self esteem, and clinical perfectionism (Table 1). Interpersonal problems were measured using two subscales (hard to be social and too dependent) and hence were not included in the CFA. For models that showed a poor t, modi cation indices were inspected and error covariance were freed if it was theoretically defensible (e.g., items were overlapped in the content). The factor loadings of the models were signi cant and ranged from 0.47 to 0.95.  Table 2 presents correlation coe cients between measured variables. Clinical perfectionism, interpersonal problems, overvaluation of shape and weight, and restraint eating signi cantly associated with binge eating. Interpersonal problems, overvaluation of shape and weight, restraint eating, and binge eating signi cantly correlated with purging behavior. Lower level of distress tolerance associated with higher level of interpersonal problems, self-esteem, overvaluation of shape and weight, binge eating and purging behaviors. There were positive signi cant relationships between clinical perfectionism and interpersonal problem, self-esteem, overvaluation of shape and weight, and restraint eating. Interpersonal problems signi cantly associated with overvaluation of shape and weight and restraint eating. Finally, there was a signi cant correlation between overvaluation of shape and weight and restraint eating.   (Fig. 2).

Correlation between variables
Consistent with the theory, signi cant path was observed between self-esteem and overvaluation of shape and weight; clinical perfectionism and overvaluation of shape and weight; Overvaluation of shape and weight and dietary restraint; overvaluation of shape and weight and binge eating; binge eating and purging; dietary restraint and purging; and interpersonal problems and binge eating. However, clinical perfectionism was not signi cantly associated with dietary restraint. Distress tolerance did not signi cantly correlate with binge eating and purging. Interpersonal problems were not associated with dietary restraint and purging. Finally, as found for the original model, dietary restraint did not correlate with binge eating.

Discussion
The primary aim of this study was to evaluate the original and enhanced CB-BN models in a sample of Iranian university student women. The results of path analysis indicated that both original and enhanced CB-BN models t with data.
Several paths of the original and enhanced CB-BN model were con rmed in the present study. Lower level of self-esteem and higher level of perfectionism associated with greater overvaluation of shape and shape. Two paths showed signi cant relationship which had not been directly mentioned in the original and enhanced CB-BN model. That is, overvaluation of shape and weight signi cantly explained binge eating periods. What can be concluded from these results might be that overvaluation of shape and weight might directly correlate with binge eating behaviors in women student sample. In other words, the student women experience some concerns about their shape and weight, but they do not or cannot restrict their eating. They might interpret their normal eating as binge eating. In addition, there were signi cant relationship between dietary restraint and purging behaviors in both models. It implied that some women might use purging behaviors just because they think they must eat as less as possible. Therefore, they engage in purging behaviors after subjective binge eating, not objective binge eating.
However, some hypothesized relationships in the original and enhanced models were not supported. First and most important, there was no signi cant relationship between dietary restraint and binge eating in both models. The dietary Restraint-binge eating relationship is a central component of the cognitive behavioral model of EDs and yet not veri ed in the current study. Previous researches indicated mixed Findings. For example, prospective (41)(42)(43) and cross-sectional studies (20,44) showed dietary restraint anticipates binge eating behaviors. However, the relationship was not supported in other structural equation modeling studies (22,44,45). These mixed results implied that the nature of the relationship between dietary restraint and binge eating remains unclear (22).
Second, the enhanced model proposed that mood intolerance associate with binge eating and purging behaviors, but the expected association between these variables were not observed in the current study.
Lower levels of distress tolerance was not associated with purging (22). Also reported no relationship between mood intolerance and binge eating and purging. This is unexpected nding, and further research is needed to understand the implications of this result. However, it is possible that the non-clinical nature of the present sample has led to the lack of correlation between these variables.

Conclusion
In summary, the ndings of the present study provide preliminary evidence for cross-cultural validity of

Consent for publication
Identi able demographic information has been removed from this manuscript to ensure anonymity. Thus, the consent to publish is not applicable.
Availability of the data Tehran University of Medical Sciences which approved and supported the study has given permission that only researches of the manuscript will have access to the dataset, so the data used in this study is not available for public view. Requests should be written to the university.

Competing Interest
The authors have no actual or potential con icts of interest including any nancial, personal or other relationships with other people or organizations within three years of beginning the work submitted that could inappropriately in uence their work.  Path analysis for the enhanced cognitive-behavioral model of EDs (standardized coefficients reported; standard errors in parenthesis; ***p < .001)