Participants
This cross-sectional study was performed from August 2018 to November 2019; in this study, 110 BPD patients and 110 healthy people were investigated. The sample size was calculated based on the study performed by Eizaguirre et al. [16]. With the assumption of r = 0.24, the probability of type I error and type II error were obtained as (α = 0.05 and Z1- α/2 = 1.96) and (β = 0.2 and Z1- α/2 = 0.84), respectively; the value of correlation coefficient was approximated to the normal distribution, and the value of r in normal distribution was calculated by the formula C = 0.5 × ln [(l + r) / (l ̶ r)]. Finally, the total sample size was obtained as 110 people based on the formula N = [(Ζα + Ζβ) ÷ C]2 + 3. The participants were selected out of the patients referring to Baharan psychiatric hospital in Zahedan, Iran, by systematic random sampling with a sampling interval of 3. The inclusion criteria included: (1) getting a score above 10 in borderline personality inventory (BPI) and approved diagnosis of the disorder based on structured clinical interview for DSM-5 personality disorders (SCID-5-PD); (2) the age range of 18-35 years; (3) the ability to read and write with reading comprehension; (4) getting a score of ≤22 in general health questionnaire (GHQ-28) for healthy people. The exclusion criteria included: (1) severe and acute physical illness; (2) brain traumatic injury; (3) the comorbidity of bipolar disorder; (4) the comorbidity of schizophrenia and other psychotic disorders; (5) epileptic disorder; (6) intellectual disability; (7) mixed personality disorder; (8) using any drug or substance that causes anorexia and bulimia; (9) failing to fill the questionnaires properly.
Procedures
After approval of the research project in the ethics committee of the Medical Faculty of the ZAUMS Zahedan (IR.ZAUMS.REC.1398.212), the informed consent form was distributed among the participants. In order to observe the Declaration of Helsinki, participation in the study was optional, and the participants could leave the study for any reason. After receiving informed consent from the participants, demographic information form, EAT-26, TAS-20, BAI, and BDI-II were distributed among them. Next, all the participants were evaluated in terms of being affected by FED using structured clinical interviews for DSM-5: research version (SCID-5-RV). For keeping the participants’ information private, the questionnaires were anonymous.
Measures
Alexithymia was assessed with the Persian version of the TAS-20; a 20-item self-report questionnaire scored based on a five-point (1-5) Likert scale. The minimum score is 20, and the maximum score is 100. The scores of 61≤ indicate alexithymia. In Iran, Besharat [20] has reported the Cronbach’s alpha coefficient of the overall alexithymia and its three subscales, ranging between 0.72 and 0.85.
Anxiety symptoms were assessed with the Persian version of the BAI; a self-report 21-item questionnaire scored based on a four-point (0-3) Likert scale. The minimum and maximum scores are 0 and 63, respectively. Kaviani et al. [21] have reported acceptable reliability and validity for the Persian version of the questionnaire (Cronbach’s alpha = 0.92).
Depressive symptoms were assessed with the Persian version of the BDI-II; a self-report 21-item questionnaire scored based on a four-point (0-3) Likert scale. The minimum and maximum scores are 0 and 63, respectively. Ghassemzadeh et al. [22] have reported acceptable reliability and validity for the Persian version of the questionnaire (Cronbach’s alpha = 0.87).
DEB symptoms were assessed with the Persian version of the EAT-26. In this 26-item questionnaire, the minimum and maximum scores are equal to 0 and 78, respectively. A score above 20 indicates the probability of being affected by FED. Ahmadi et al. [23] have reported acceptable reliability and validity for the Persian version of this questionnaire (internal consistency = 0.76-0.92).
In BPI, a 53-item questionnaire (answered by yes or no), if the person’s score for the 20 items of the cutoff score is above 10, the person is highly likely to be affected by BPD. Mohammadzadeh [24] has reported acceptable reliability and validity for the Persian version of this questionnaire (Cronbach’s alpha = 0.70-0.85).
SCID-5-PD is a semi-structured clinical interview for researchers and clinicians, and it evaluates DSM-5 personality disorders under three clusters of A, B, C, and other specific personality disorders. Several studies have reported acceptable reliability and validity for SCID-5-PD [25].
SCID-5-RV is a semi-structured interview for major DSM-5 diagnoses, and it is performed by a trained clinician or health expert who is familiar with the diagnostic criteria and classification of disorders in DSM-5. Several studies have reported acceptable reliability and validity for SCID-5-RV [26].
GHO-28 is a 28-item questionnaire in which items are scored in the range of 0-3. The overall score ranges between 0 and 84. Getting a score of ≤22 indicates a person’s mental health. In Iran, Ebrahimi et al. [27] have reported acceptable reliability and validity for this scale (Cronbach’s alpha = 0.97).
Data analysis
Statistical analysis was performed by descriptive statistics, including mean and standard deviation. Kruskal-Wallis test was used for demographic comparison of the three studied groups, and analysis of variance (ANOVA) was used to compare the mean scores of BAI, BDI, TAS-20, and EAT-26. The correlation between the variables was evaluated by the Pearson correlation coefficient. The model proposed by Baron and Kenny [28] was used to investigate the mediating role of anxiety and depression in the relationship between alexithymia and DEB. According to this model, mediation is approved by the following four conditions: (1) the independent variable (alexithymia) affects the dependent variable (DEB); (2) the independent variable affects the mediator variables (anxiety and depression); (3) regarding the effect of the independent variable, the mediator variable affects the dependent variable; (4) regarding the effect of the mediator variable, the effect of the independent variable on the dependent variable is decreased. Hierarchical multiple regression was used to investigate the predicting role of the studied variables. Furthermore, given the relationship of sociodemographic factors (including age, gender, marital status, education level, and income) with anxiety, depression [29-32], and FED [33, 34] found in previous studies, the factors as mentioned above were considered as covariates in regression analysis. Meanwhile, data analysis was done by SPSS 25, and the significance level was considered as P ˂ 0.05.