The effectiveness of acceptance and commitment therapy for social anxiety disorder: a randomized clinical trial

Objective: Acceptance and commitment therapy has been used to treat anxiety disorders recently. The purpose of this study was to investigate the effectiveness of acceptance and commitment therapy for psychological symptoms in students with social anxiety disorder, including difficulty in emotion regulation, psychological flexibility based on experiential avoidance, self-compassion, and external shame. Methods: This study was a semi-experimental clinical trial. Twenty four students with social anxiety disorder were randomly divided into two groups after initial evaluations: an experimental group (12 subjects) and a control group (12 subjects). The experimental group received 12 treatment sessions based on a protocol of acceptance and commitment therapy for anxiety disorders, and the control group was put on a waiting list. Self-Compassion (SCS), Difficulty in Emotion Regulation (DERS), External Shame (ESS), Social Anxiety (SPIN), and Acceptance and Action (AAQ-II) questionnaires were used to assess participants. Data were analyzed using SPSS. Results: Acceptance and commitment therapy was shown to be effective at the post-test and follow up stages for reducing external shame, social anxiety, and difficulty in emotion regulation and its components, and for increasing psychological flexibility and self-compassion (p < 0.05). The largest effect size of treatment was for increase of psychological flexibility and the lowest efficacy was for the components “difficulty in impulse control” and “limited access to emotional strategies” at the post-test and follow-up stages, respectively. Conclusion: Acceptance and commitment therapy may be an appropriate psychological intervention for reducing the symptoms of students with social anxiety disorder and helping them to improve psychological flexibility. Emotion and related problems can be identified as one of the main targets of this treatment. Clinical trial registration:


Introduction
Social anxiety disorder is characterized by significant fear or anxiety about one or more social situations in which the person is exposed to unfamiliar people or to possible scrutiny by others. 1 Social anxiety disorder is one of the most common disorders among young people, 2,3 affecting approximately 13% of the population. 4 This disorder, in addition to isolating some patients socially 5 and having a destructive effect on occupation and on educational and interpersonal performance, 6 can inflict huge costs on all countries' economies every year. 7,8 Therefore, comprehensive study of this disorder and use of evidence-based interventions are important.
Many studies have shown that people with social anxiety disorder have ineffective experiential avoidance. 9,10 This is related to a person's desire for change and sensitivity to internal situations and events. 11 Previous studies have identified selfcompassion, [12][13][14][15] difficulty in emotion regulation, [16][17][18] and extreme feelings of shame 19,20 as the most important psychological problems experienced by people with social anxiety disorder. Clinicians have used pharmacological and psychological interventions to attempt to improve the symptoms of social anxiety disorder. [21][22][23][24][25][26][27][28] Although some psychological interventions, such as cognitivebehavioral therapy, have demonstrated efficacy for treatment of patients with social anxiety, some people did not respond to treatment or symptoms remained. 22 One treatment that has been used recently to treat anxiety disorders and has demonstrated effectiveness for reducing anxiety symptoms is acceptance and commitment therapy (ACT). [23][24][25][26] ACT is derived from the modern theory of cognition and language 27 and is classified as a third-wave psychological treatment, in which some cognitivebehavioral therapy concepts have been changed. 28 The main assumption underlying ACT is that humans experience disturbing thoughts, emotions, and feelings 29 and that their attempts to change or to get rid of these experiences are ineffective, which sometimes exacerbates these disturbances and ultimately leads to avoidance. 30 The six core psychological processes employed in this treatment are Acceptance, Defusion, Self as context, Contact with the present moment, Values, and Committed action. 31 These six processes are all implemented using metaphors, empirical exercises, and logical contradictions to escape the literal content of the language and interact more with the ongoing flow of experience at the present moment. 32 The purpose of this treatment is to reduce experiential avoidance and increase psychological flexibility. 30

Statistical analysis
SPSS software was used to analyze findings and statistical data. Multivariate analysis of covariance was used to analyze the effectiveness of the treatment in the experimental group on the variables evaluated, in comparison with the control group. The chi-square test was used to compare the number of participants and the independent t test was used to compare the mean age of the experimental and control groups.

Anxiety Disorders Interview Schedule for DSM-IV (ADIS-IV)
This is a semi-structured, clinical and diagnostic interview for anxiety disorders developed in 1994 by Brown et al. 33  Waiting list group, completed follow-up:

students
Experimental group, after completion of pre-test:

students
Experimental group, after completion of post-test:

students
Experimental group, completed follow-up:

students
Excluded subjects (21) Comorbidity with other anxiety and mood disorders (13) Substance abuse history (7) Other factors (1) The validity of the Persian version of this program has been confirmed and its retest reliability coefficient was reported as 0.83. 34 In this study, this measurement will be used to screen for social anxiety disorder, to confirm clinical diagnosis, and to assess clinical severity.

Self-Compassion Scale (SCS)
This questionnaire consists of 26 items with a fivepoint Likert response scale measuring three bipolar components in the form of six sub-scales. These components are Self-kindness vs. Self-judgment, Common humanity vs. Isolation, and Mindfulness vs.
Over-identification. 35 The Cronbach's alpha coefficient of 0.92 represents an internal consistency superior to the original version of this scale. Convergent validity, discriminant validity, and appropriate retest reliability for this scale have been reported. 35 In an Iranian student sample, the six-factor structure of the validation questionnaire was confirmed and a Cronbach's alpha coefficient of 0.86 for the whole scale was reported.
Cronbach's alpha coefficients for sub-scales were in the range of 0.79-0.85. 35

Difficulty in Emotion Regulation Scale (DERS)
This scale is a comprehensive measurement for assessing difficulty in emotion regulation that is based on the concept of mindfulness and acceptance and was designed in 2004. 36 A self-report measure with 36 items that measure usual levels of difficulty in emotion regulation as well as its specific dimensions. 37  Each option is scored from "never" to "almost always" using Likert scales. A higher score indicates greater external shame. 39 The reliability of this measure was reported as desirable, based on its Cronbach's alpha  41 The questionnaire also has good validity. 41 The reliability of this questionnaire in Iran was 0.84 for test-retest and 0.84 for Cronbach's alpha and its validity was also desirable. 41 The results of factor analysis by principal component analysis revealed three components: acceptance, experience without judgment, and action. 40

Social Phobia Inventory (SPIN)
This questionnaire is a self-report scale with 17 items that are designed to assess anxiety or social anxiety. 42 This scale consists of three subscales of fear (6 items), avoidance (7 items), and physiological discomfort (4 items), and each item has a 5-degree Likert response scale, ranging from 1 to 5. 42 A cut-off score of 19 is used to screen for social anxiety. The testretest reliability of this scale has been reported as 0.78 to 0.89 in groups with diagnosed social anxiety and its internal consistency has been reported as 94% in a group of healthy individuals. 42 The convergent validity of this questionnaire was reported as 0.57-0.85. 42

An ACT protocol for anxiety disorders developed by
Eifert and Forsyth 24 was used with the intervention group.
This protocol consists of 12 sessions, each with specific goals. Activities were tailored to the individual needs of clients, while standard sessions were maintained.
In ACT, emphasis is put on establishment of a context

Results
Based on demographic variables, the mean age of the participants was 22.12±1.08. Twenty-four subjects participated in this study, 17 of whom were women (70.8%) and 7 of whom were men (29.2%). There was no significant difference between the two groups in terms of age (p > 0.05). There was no significant difference between the two groups in terms of gender (Table 1). One member of each group was excluded from the study because of non-completion of the evaluation and drop-out from treatment sessions respectively.   Data presented as mean ± standard deviation. ESS = External Shame Scale; AAQ-II = Acceptance and Action in Social Anxiety Questionnaire, 2nd edition; SPIN = Social Phobia Inventory; SCS = Self-Compassion Scale; DERS = Difficulty in Emotion Regulation Scale.  shows the highest degree of efficacy for ACT. Among the variables studied, the components of "difficulty in impulse control" and "limited access to emotional strategies" had the smallest effect sizes in the post-test and follow-up stages, respectively.

Discussion
The purpose of this study was to evaluate the effectiveness of ACT for improvement of psychological symptoms in students with social anxiety disorder.  45 Luoma et al. 45 showed that ACT is effective for reducing shame in people with a history of substance abuse. In another study, 46 it was shown that experiential avoidance can be regarded as a mediator of shame and self-harmful behaviors. On the other hand, shame can be a sign and experiential avoidance is a characteristic experienced by people with social anxiety disorder, 9,[19][20][21] and experiential avoidance is one of the criteria of psychological inflexibility in ACT. Therefore, it can be expected that ACT is effective for reducing feelings of shame and experiential avoidance, and subsequently for reducing the self-harmful behaviors of people with social anxiety disorder, which has been detailed in several studies. [19][20][21] In line with this conclusion, in the present study this treatment was effective at reducing the feelings of shame experienced by students with social anxiety disorder. The main purpose of this study was to investigate the effectiveness of ACT at reducing the difficulty in emotion regulation of people with social anxiety disorder, which has been shown to be a major concern in their daily lives. 50,51 Of the components of difficulty in emotion regulation, ACT had the greatest impact on "lack of acceptance of emotional responses". In view of the main psychological processes in this treatment, this result was not expected. So far, many studies have been conducted on the effectiveness of psychological treatments on emotions and related problems. [52][53][54] It has been argued that ACT emphasizes the experience of problematic emotions rather than trying to change knowledge or reduce emotional levels. 51 It seems that ACT is also effective for emotional problems and changes in levels of emotion. The results presented in other studies are in line with this. 50,51 In the present study, the results showed that the experimental group compared favorably to the control group in ability to effectively reduce the difficulty in emotion regulation and its components.
Several limitations of this study should be noted. First, the sample size limits the capability for generalization, which it is recommended should be addressed in future studies to increase reliability of results. Second, the sample studied consisted entirely of students, who are not comparable with the general population in terms of social, economic, or intellectual capabilities. Third, the use of a waiting list group as control group is a limitation. It is suggested that more dynamic control groups be used to help clients in future studies.

Conclusion
Given the limitations of this study, it can be concluded that, by increasing concentration on self-compassion,