Bond, F. W., & Bunce, D. (2000). Mediators of change in emotion-focused and problem-focused worksite stress management interventions. Journal of Occupational Health Psychology, 5(1), 156–163. https://doi.org/10.1037/1076-8998.5.1.156

Type of Study: Randomized controlled trial
Number of Participants: 90

Population:

• Age — 19–58 years
• Race/Ethnicity — 60 Caucasian, 9 Hispanic, 3 African American, 2 Native American, and 1 Southeast Asian
• Gender — 45 Male and 45 Female
• Status — Participants were volunteer employees of a large media organization.

Location/Institution: Not specified

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to examine how Acceptance and Commitment Therapy (ACT) and Innovation Promotion Program (IPP) affect, through their mediating variables, both mental health outcomes (general mental health and depression) and work-related outcomes (job motivation, job satisfaction, and propensity to innovate). Participants were randomly assigned to an ACT group, an IPP, or a waitlist control group. Measures utilized include Acceptance and Action Questionnaire (AAQ), Dysfunctional Attitude Survey (DAS), General Health Questionnaire-12 (GHQ), Beck Depression Inventory (BDI), the Work change measure, the Intrinsic Job Motivation scale, the Intrinsic Job Satisfaction measure, and the Propensity to Innovate measure. Results indicate that ACT significantly improved mental health outcomes (GHQ and BDI) and a work-related variable, and propensity to innovate. General mental health also improved in the ACT intervention group. The problem-focused IPP intervention also significantly improved a mental health (BDI) and a work-related (propensity to innovate) variable. However, neither intervention influenced job satisfaction or motivation and there were also no significant changes in the control group. Changes in the ACT condition were mediated only by the acceptance of undesirable thoughts and feelings. In the IPP condition, outcome change was mediated only by attempts to modify stressors. Limitations include small sample size, selection bias due to the voluntary nature of participation, and attrition.

Length of controlled postintervention follow-up: Approximately 3 months.

Forman, E. M., Herbert, J. D., Moitra, E., Yeomans, P. D., & Geller, P. A. (2007). A randomized controlled effectiveness trial of Acceptance and Commitment Therapy and Cognitive Therapy for anxiety and depression. Behavior Modification, 31(6), 772–799. https://doi.org/10.1177/0145445507302202

Type of Study: Randomized controlled trial
Number of Participants: 101

Population:

• Age — 18–52 years (Mean=27.87 years)
• Race/Ethnicity — 64% Caucasian, 12% Black, 11% Asian, and 3% Latino
• Gender — 80% Women
• Status — Participants were from a university student counseling center.

Location/Institution: Not specified

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to compare the relative effectiveness of Cognitive Therapy (CT) and Acceptance and Commitment Therapy (ACT) in the treatment of patients presenting with combinations of anxiety and mood disorders in an outpatient clinic. Participants were randomly assigned to CT or to ACT. Measures utilized include therapist conducted semistructured interviews using an instrument based on the Diagnostic and Statistical Manual of Mental Disorders–IV–Text Revision (DSM-IV-TR), the Reaction to Treatment Questionnaire (RTQ), the Beck Anxiety Inventory, Global Assessment of Functioning Scale (GAF), Clinical Global Impression Scale (CGI), Quality of Life Index (QOLI), Satisfaction with Life Scale (SLS), the Kentucky Inventory of Mindfulness Skills (KIMS), the Beck Depression Inventory (BDI–II), the Acceptance and Action Questionnaire (AAQ), and the Outcome Questionnaire (OQ). Results indicate that participants receiving CT and ACT evidenced large, equivalent improvements in depression, anxiety, functioning difficulties, quality of life, life satisfaction, and clinician-rated functioning. Whereas improvements were equivalent across the two groups, the mechanisms of action appeared to differ. Changes in “observing” and “describing” one’s experiences appeared to mediate outcomes for the CT group relative to the ACT group, whereas “experiential avoidance,” “acting with awareness,” and “acceptance” mediated outcomes for the ACT group. Overall, the results suggest that ACT is a viable treatment that can be disseminated, the effectiveness of which appears equivalent to that of CT. Limitations include high attrition rate, modest sample size, overlap of therapeutic techniques across the two approaches, and lack of adequate follow-up.

Length of controlled postintervention follow-up: Not specified.

Petersen, C. L., & Zettle, R. D. (2009). Treating inpatients with comorbid depression and alcohol use disorders: A comparison of Acceptance and Commitment Therapy versus treatment as usual. The Psychological Record, 59(4), 521–536. https://doi.org/10.1007/BF03395679

Type of Study: Randomized controlled trial
Number of Participants: 24

Population:

• Age — 36–39 years
• Race/Ethnicity — 15 Caucasian, 8 African American, and 1 Other
• Gender — 12 Female and 12 Male
• Status — Participants were individuals involuntarily committed to a chemical dependency unit a southern state hospital.

Location/Institution: Not specified

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to describe inpatients involuntarily committed to a chemical dependency unit and exhibiting a co-occurring depressive disorder. Participants were randomly assigned to either individual sessions of Acceptance and Commitment Therapy (ACT) or treatment as usual (TAU). Measures utilized include the Hamilton Rating Scale (HRS), the Beck Depression Inventory–Second Edition (BDI–II), the Acceptance and Action Questionnaire (AAQ), the Problems Assessment for Substance-Using Psychiatric Patients (PASUPP), and The Alcohol Timeline Followback interview (Alcohol TFLB). Results indicate that there were significant, but equivalent, reductions in levels of depression for both treatment conditions. However, participants randomly assigned to receive ACT required a shorter treatment phase and smaller dose of individual therapy to meet criteria for discharge compared to their TAU counterparts. Limitations include small sample size and lack of post-treatment follow-up.

Length of controlled postintervention follow-up: None.

Twohig, M. P., Hayes, S. C., Plumb, J. C., Pruitt, L. D., Collins, A. B., Hazlett-Stevens, H., & Woidneck, M. R. (2010). A randomized clinical trial of Acceptance and Commitment Therapy versus progressive relaxation training for obsessive-compulsive disorder. Journal of Consulting and Clinical Psychology, 78(5), 705–716. https://doi.org/10.1037/a0020508

Type of Study: Randomized controlled trial
Number of Participants: 79

Population:

• Age — Mean=37 years
• Race/Ethnicity — 89% Caucasian, 5% Latino/a, 3% Asian American, 3% Native American, and 1% African American
• Gender — 66% Female
• Status — Participants were individuals with obsessive compulsive disorder (OCD).

Location/Institution: Two Western states within the U.S.

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to investigate the effectiveness of eight sessions of Acceptance and Commitment Therapy (ACT) for adult obsessive compulsive disorder (OCD) compared to Progressive Relaxation Training (PRT). Participants were randomly assigned to 8 sessions of ACT or PRT with no in-session exposure. Measures utilized include the Structured Clinical Interview Scale for DSM-IV (SCID), the Yale-Brown Obsessive Compulsive Scale (YBOCS), Beck Depression Inventory-II, Quality of Life Scale, Acceptance and Action Questionnaire, Thought Action Fusion Scale, Thought Control Questionnaire, and the Treatment Evaluation Inventory-Short Form. Results indicate that both treatments were equally credible and treatment integrity data were good for both conditions, but results showed greater improvement at post treatment and at follow-up in OCD symptoms for ACT as compared to PRT. ACT resulted in a greater number of participants showing clinically significant improvement compared to PRT and had a significantly greater effect on depression among those reporting at least mild depression before treatment. Limitations include self-reports on measures, lack of generalizability to other ethnic populations due to the racial/ethnic distribution, changes to the PRT intervention, and lack of long-term follow-up.

Length of controlled postintervention follow-up: 3 months.

Muto, T., Hayes, S. C., & Jeffcoat, T. (2011). The effectiveness of Acceptance and Commitment Therapy bibliotherapy for enhancing the psychological health of Japanese college students living abroad. Behavior Therapy, 42(2), 323–335. https://doi.org/10.1016/j.beth.2010.08.009

Type of Study: Randomized controlled trial
Number of Participants: 70

Population:

• Age — 20–26 years (Mean= 23.6 years)
• Race/Ethnicity — 100% Japanese
• Gender — 44 Female
• Status — Participants were Japanese international students.

Location/Institution: University of Nevada, Reno

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to discuss results of the effects of Acceptance and Commitment Therapy (ACT) on half of the population of Japanese international students in a Western university in the United States. Participants were randomly assigned to a wait-list or to receive a Japanese translation of a broadly focused ACT self-help book. Measures utilized include individual emails with coded links that were sent to participants to complete questionnaires or quizzes, the General Health Questionnaire 12-item (GHQ-12), the Depression Anxiety Stress Scales (DASS-21), and the Acceptance and Action Questionnaire (AAQ-II). Results indicate that students receiving the book showed significantly better general mental health at post and follow up. Moderately depressed or stressed, and severely anxious students showed improvement compared to those not receiving the book. These patterns were repeated when the wait-list participants finally received the book. Improvements in primary outcomes were related to how much was learned about an ACT model from the book. Limitations include lack of generalizability to other ethnic and gender populations, and lack of long-term follow-up.

Length of controlled postintervention follow-up: 2 months.

Jeffcoat, T., & Hayes, S. C. (2012). A randomized trial of ACT bibliotherapy on the mental health of K-12 teachers and staff. Behaviour Research and Therapy, 50(9), 571–579. https://doi.org/10.1016/j.brat.2012.05.008

Type of Study: Randomized controlled trial
Number of Participants: 236

Population:

• Age — 30–60 years
• Race/Ethnicity — Not specified
• Gender — 91% Female
• Status — Participants were teachers and administrators.

Location/Institution: Washoe County School District (WCSD)

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to discuss K–12 school personnel responding to a wellness-oriented program announcement. Participants were randomly assigned to Acceptance and Commitment Therapy (ACT) self-help volume or to a wait list. Measures utilized include individual emails with coded links were sent to participants to complete questionnaires or quizzes, the General Health Questionnaire 12-item (GHQ-12), the Depression Anxiety Stress Scales (DASS-21), the Kentucky Inventory of Mindfulness Skills (KIMS), and the Acceptance and Action Questionnaire (AAQ-II). Results indicate that participants showed significant improvement in psychological health. Significant preventive effects for depression and anxiety were observed along with significant ameliorative effects for those in the clinical ranges of depression, anxiety and stress. Follow-up general mental health, depression, and anxiety outcomes were related to the manner in which participants used the workbook and to post levels of psychological flexibility. Limitations include lack of generalizability due to population being 90% female and lack of long-term follow-up.

Length of controlled postintervention follow-up: 10 weeks.

Folke, F., Parling, T., & Melin, L. (2012). Acceptance and Commitment Therapy for depression: A preliminary randomized controlled trial for unemployment on long-term sick leave. Cognitive and Behavioral Practice, 19(4), 583–594. https://doi.org/10.1016/j.cbpra.2012.01.002

Type of Study: Randomized controlled trial
Number of Participants: 34

Population:

• Age — Mean=43 years
• Race/Ethnicity — 100% Caucasian
• Gender — 88% Female
• Status — Participants were citizens unable to earn their income due to disability or illness (i.e., individuals on sick leave or disability pension) who also met criteria for unipolar depression.

Location/Institution: Regional Social Insurance Office in Sweden

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to examine a brief version of Acceptance and Commitment Therapy (ACT) in a sample of individuals on long-term sick leave due to depression. Participants were randomly assigned to the ACT condition consisting of 1 individual and 5 group sessions or to services as usual. Measures utilized include the Beck Depression Inventory, the General Health Questionnaire, the Perceived Stress Scale, and the World Health Organization Quality of Life assessment. Results indicate that from pretreatment to 18-month follow-up, the ACT participants improved significantly on measures of depression, general health, and quality of life compared to participants in the control condition. The conditions did not differ regarding sick leave and employment status at any time point. Limitations include the lack of standardized diagnosis procedure, lack of information on services received by the usual care group, and small sample size.

Length of controlled postintervention follow-up: 18 months.

Losada, A., Marquez-Gonzalez, M., Romero-Moreno, R., Mausbach, B. T., Lapez, J., Fernandez-Fernandez, V., & Nogales-Gonzalez, C. (2015). Cognitive–behavioral therapy (CBT) versus Acceptance and Commitment Therapy (ACT) for dementia family caregivers with significant depressive symptoms: Results of a randomized clinical trial. Journal of Consulting and Clinical Psychology, 83(4), 760–772. https://doi.org/10.1037/ccp0000028

Type of Study: Randomized controlled trial
Number of Participants: 135

Population:

• Age — 61–62 years
• Race/Ethnicity — Not specified
• Gender — 84% Female
• Status — Participants were recruited from internet advertisement and Social and Health Care Centers.

Location/Institution: Madrid, Spain

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to compare the differential efficacy of Acceptance and Commitment Therapy (ACT) and Cognitive–Behavioral Therapy (CBT) for dementia family caregivers. Participants were randomly assigned to ACT, CBT, or a control group (CG). Measures utilized include the Global Deterioration Scale for Assessment of Primary Degenerative Dementia, Barthel Index, Revised Memory and Behavior Problems Checklist, CES–D, Profile of Mood States (POMS), Leisure Time Satisfaction scale, Experiential Avoidance in Caregiving Questionnaire, and the Dysfunctional Thoughts About Caregiving Questionnaire. Results indicate that ACT and CBT interventions seem to be superior to CG in terms of statistical and clinically significant reduction of distress (e.g., depression and anxiety). Regarding depressive symptomatology, the results of the study suggest that both ACT and CBT interventions are superior to CG at postintervention (with large effect sizes), although they are only maintained in CBT at follow-up (medium effect size). Limitations include caregivers who volunteered to participate and may not be representative of the overall caregiver population; participants in the ACT and CBT conditions had eight weekly individual sessions with a therapist, whereas the CG had a single 2-hour group workshop; and lack of generalizability due to gender.

Length of controlled postintervention follow-up: 6 months.

Pots, W. T., Fledderus, M., Meulenbeek, P. A., Peter, M., Schreurs, K. M., & Bohlmeijer, E. T. (2016). Acceptance and Commitment Therapy as a web-based intervention for depressive symptoms: randomised controlled trial. The British Journal of Psychiatry, 208(1), 69–77. https://doi.org/10.1192/bjp.bp.114.146068

Type of Study: Randomized controlled trial
Number of Participants: 236

Population:

• Age — 20–73 years (Mean=46.85)
• Race/Ethnicity — Not specified
• Gender — 76% Female, 24% Male
• Status — Participants were recruited from internet advertisement.

Location/Institution: The Netherlands

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to compare the efficacy of a guided web-based intervention based on Acceptance and Commitment Therapy (ACT) with an active control (expressive writing) and a waiting-list control condition. Participants were randomly assigned to ACT, expressive writing,  or waiting-list control. Measures utilized include the Dutch version of the Center for Epidemiological Studies –Depression (CES-D), the Dutch version of the Mini International Neuropsychiatric Interview (MINI) and the Sheehan Disability Scale (SDS), Hospital Anxiety and Depression Scale – Anxiety subscale (HADS-A), Mental Health Continuum – Short Form (MHC-SF), Acceptance and Action Questionnaire II (AAQ-II), and the Five Facet Mindfulness Questionnaire – Short Form (FFMQ-SF). Results indicate that at post-treatment significant reductions in depressive symptoms were found following the ACT intervention, compared with the control group and the expressive writing intervention. The effects were sustained at 6-month and 12-month follow-up. Limitations include possibility of self-selection bias, generalizability due to high education level of the participants, and the interventions differed somewhat between treatments.

Length of controlled postintervention follow-up: 6 and 12 months.

A-Tjak, J. G. L., Morina, N., Topper, M., & Emmelkamp, P. M. G. (2018). A randomized controlled trial in routine clinical practice comparing Acceptance and Commitment Therapy with Cognitive Behavioral Therapy for the treatment of major depressive disorder. Psychotherapy and Psychosomatics, 87(3), 154–163. https://doi.org/10.1159/000486807

Type of Study: Randomized controlled trial
Number of Participants: 82

Population:

• Age — Mean=40.45–42.52 years
• Race/Ethnicity — 67 Dutch, 13 Non-European, and 2 European
• Gender — 42 Female and 40 Male
• Status — Participants were adults with major depressive disorder.

Location/Institution: Amsterdam

Summary: (To include basic study design, measures, results, and notable limitations)
The purpose of the study was to compare Acceptance and commitment Therapy (ACT) with cognitive behavioral therapy (CBT) for depression. Participants were randomly assigned to either ACT or CBT. Measures utilized include the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for Major Depressive Disorder, the Personality Disorder Belief Questionnaire (PBQ), the Quick Inventory of Depressive Symptomatology (QIDS-SR16), the Hamilton Depression Rating Scale (HDRS-17), and the European Health Interview Surveys Quality of Life Scale (EUROHIS). Results indicate that after treatment, the rates of remission from depression were 75% and 80% for the ACT and CBT conditions, respectively. Patients in both conditions further reported significant and large reductions in depressive symptoms and improvement in quality of life from before to after treatment as well as at the follow-up. Findings indicated no significant differences between the two intervention groups. Limitations include the study was underpowered to detect smaller differences in effectiveness between ACT and CBT, lack of control group, and did not assess interrater reliability for the SCID diagnoses and the HDRS.

Length of controlled postintervention follow-up: 6 months.

A-Tjak, J. G. L., Morina, N., Topper, M. & Emmelkamp, P. M. G. (2021). One year follow-up and mediation in Cognitive Behavioral Therapy and Acceptance and Commitment Therapy for adult depression. BMC Psychiatry, 21(1). https://doi.org/10.1186/s12888-020-03020-1

Type of Study: Randomized controlled trial
Number of Participants: 82

Population:

• Age — Mean=40.45–42.52 years
• Race/Ethnicity — 67 Dutch, 13 Non-European, and 2 European
• Gender — 42 Female and 40 Male
• Status — Participants were adults with major depressive disorder.

Location/Institution: Amsterdam

Summary: (To include basic study design, measures, results, and notable limitations)
The study used the same sample as A-Tjak et al. 2018. The purpose of the study was to compare the long-term efficacy of Acceptance and commitment Therapy (ACT) with Cognitive Behavioral Therapy (CBT) for depression. Participants were randomly assigned to either ACT or CBT. Measures utilized include the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID-I), the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) criteria for Major Depressive Disorder, the Personality Disorder Belief Questionnaire (PBQ), the Quick Inventory of Depressive Symptomatology (QIDS-SR16), the Hamilton Depression Rating Scale (HDRS-17), and the European Health Interview Surveys Quality of Life Scale (EUROHIS). Results indicate that participants in both conditions reported significant and large reductions of depressive symptoms and improvement in quality of life 12 months following treatment. Findings indicated no significant differences between the two interventions. Dysfunctional attitudes and decentering mediated treatment effects of depressive symptoms in both CBT and ACT, whereas experiential avoidance mediated treatment effects in ACT only. Limitations include the study was underpowered to detect smaller differences in effectiveness between ACT and CBT and lack of control group.

Length of controlled postintervention follow-up: 12 months.