Skip to main content Accessibility help

A Randomised Controlled Trial of Acceptance and Commitment Therapy and Cognitive-Behaviour Therapy for Generalised Anxiety Disorder

  • Elbina Avdagic (a1), Shirley A. Morrissey (a1) (a2) and Mark J. Boschen (a1) (a2)


The study examined the relative efficacy of group acceptance and commitment therapy (ACT) for generalised anxiety disorder (GAD) compared to group cognitive-behavioural therapy (CBT). Fifty-one individuals with GAD were randomly allocated to a 6-week intervention, either ACT or CBT. Participants were assessed at pre-treatment, post-treatment, and 3-month follow-up on symptom measures, quality of life, and process measures. Data from 38 participants (19 in each group) were available at post-assessment, indicating significant improvements on all measures for both treatment conditions. Treatment gains were maintained at follow-up, with significant further improvements in anxiety, depression and stress symptoms for both groups. While no between-group differences were found at treatment completion, a significant interaction indicating steeper reduction in worrying symptoms (d = .79) from pre- to post-assessment was found for the ACT group compared to the CBT group. Furthermore, in relation to worrying, at treatment completion 78.9% of participants in the ACT group achieved reliable change compared to 47.4% of participants in the CBT group. However, both groups showed equivalent reliable change rates of 60% at the follow-up assessment. The results suggest that group ACT was as efficacious as group CBT. While participants in the ACT group maintained treatment gains at follow-up, participants in the CBT group continued to improve between post-assessment and follow-up.


Corresponding author

Address for correspondence: Associate Professor Shirley Morrissey, School of Applied Psychology and Griffith Health Institute, Griffith University, Gold Coast QLD 4222, Australia. Email:


Hide All
Arch, J.J., Eifert, G.H., Davies, C., Vilardaga, J.C.P., Rose, R.D., & Craske, M.G. (2012). Randomized clinical trial of cognitive behavioral therapy (CBT) versus acceptance and commitment therapy (ACT) for mixed anxiety disorders. Journal of Consulting and Clinical Psychology, 80 (5), 750765. doi:10.1037/a0028310
Americal Psychiatric Association. (1994). Diagnostic and statistical manual of mental disorders (4th ed.). Washington DC: Author.
Ballenger, J.C., Davidson, J.R.T., Lecrubier, Y., Nutt, D.J., Borkovec, T.D., Rickels, K., . . . Wittchen, H.-U. (2001). Consensus statement on generalized anxiety disorder from the International Consesus Group on Depression and Anxiety. Journal of Clinical Psychiatry, 62(Suppl. 11), 5358.
Bond, F.W., & Bunce, D. (2003). The role of acceptance and job control in mental health, job satisfaction, and work performance. Journal of Applied Psychology, 88 (6), 10571067. doi: 10.1037/0021-9010.88.6.1057
Borkovec, T.D., & Ruscio, A.M. (2001). Psychotherapy for generalized anxiety disorder. Journal of Clinical Psychiatry, 62(Suppl. 11), 3742.
Boschen, M.J. (2008). Publication trends in individual anxiety disorders: 1980–2015. Journal of Anxiety Disorders, 22, 570575. doi:10.1016/j.janxdis.2007.04.004
Brown, T.A., & Barlow, D.H. (1992). Coromobidity among anxiety disorders: implications for treatment and DSM-IV. Journal of Consulting and Clinical Psychology, 60, 835844.
Brown, T.A., Barlow, D.H., & Liebowitz, M.R. (1994). The empirical basis of generalized anxiety disorder. The American Journal of Psychiatry, 151 (9), 12721280.
Brown, T.A., Di Nardo, P.A., Lehman, C.L., & Campbell, L.A. (2001). Reliability of the DSM-IV anxiety and mood disorders: Implications for the classification of emotional disorders. Journal of Abnormal Psychology, 110 (1), 4958.
Buhr, K., & Dugas, M.J. (2002). The intolerance of uncertainty scale: Psychometric properties of the English version. Behaviour Research and Therapy, 40 (8), 931945. doi:10.1016/S0005-7967(01)00092-4
Covin, R., Ouimet, A.J., Seeds, P.M., & Dozois, D.J.A. (2008). A meta-analysis of CBT for pathological worry among clients with GAD. Journal of Anxiety Disorders, 22 (1), 108116. doi:10.1016/j.janxdis.2007.01.002
Devilly, G.J. (2004). The Effect Size Generator for Windows: Version 2.3 [computer program]. Melbourne, Australia: Centre for Neuropsychology, Swinburne University.
Di Nardo, P.A., Brown, T.A., & Barlow, D.H. (1994). Anxiety Disorders Interview Schedule for DSM-IV (ADIS-IV). New York: Graywind.
Eifert, G.H., & Forsyth, J.P. (2005). Acceptance and commitment therapy for anxiety disorders: A practitioner's treatment guide to using mindfulness, acceptance, and values-based behavior change strategies. Oakland, CA: New Harbinger Publications.
Erickson, T.M., & Newman, M.G. (2005). Cognitive behavioral psychotherapy for generalized anxiety disorder: A primer. Expert Review of Neurotherapeutics, 5, 247257.
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), 772799. doi:10.1177/0145445507302 202
Forman, E.M., Shaw, J.A., Goetter, E.M., Herbert, J.D., Park, J.A., & Yuen, E.K. (2012). Long-term follow-up of a randomized controlled trial comparing acceptance and commitment therapy and standard cognitive behavior therapy for anxiety and depression. Behavior Therapy, 43 (4), 801811. doi:10.1016/j.beth.2012.04.004
Forsyth, J.P., & Eifert, G.H. (2007). The mindfulness and acceptance workbook for anxiety: A guide to breaking free from anxiety, phobias and worry using acceptance and commitment therapy. Oakland, CA: New Harbinger Publications.
Frish, M.B. (1994). Manual and treatment guide for the Quality of Life Inventory. Minneapolis, MN: Pearson Assessment.
Frish, M.B., Cornwell, J., Villanueva, M., & Retzlaff, P.J. (1992). Clinical validation of the Quality of Life Inventory: A measure of life satisfaction of use in treatment planning and outcome assessment. Psychological Assessment 4 (1), 92101.
Glaser, N.M., Blackledge, J.T., Shepherd, L.M., & Deane, F.P. (2009). Brief group ACT for anxiety. In Blackledge, J.T., Ciarrochi, J., & Deane, F.P. (Eds.), Acceptance and commitment therapy: Contemporary theory research and practice (pp. 175200). Brisbane, Australia: Australian Academic Press.
Gould, R.A., Safren, S.A., Washington, D.O., & Otto, M.W. (2004). A meta-analytic review of cognitive-behavioral treatments. In Heimberg, R.G., Turk, C.A., & Mennin, D.S. (Eds.), Generalized anxiety disorder: Advances in research and practice (pp. 248264). New York: Guilford Press.
Hayes, S.C. (2004). Acceptance and commitment therapy, relational frame theory, and the third wave of behavioral and cognitive therapies. Behavior Therapy, 35 (4), 639665. doi:10.1016/S0005-7894(04)80013-3
Hayes, S.C., Strosahl, S., & Wilson, K. (1999). Acceptance and commitment therapy: An experiential approach to behavioural change. New York: Guilford Press.
Hayes, S.C., Strosahl, S., Wilson, K.G., Bissett, R.T., Pistorelo, J., Toarmino, D., . . . McCurry, S.M. (2004). Measuring experiential avoidance: A preliminary test of a working model. The Psychological Record, 54 (4), 553578.
Hayes-Skelton, S.A., Roemer, L., & Orsillo, S.M. (2013). A randomized clinical trial comapring an acceptance-based behavior therapy to applied relaxation for generalized anxiety disorder. Journal of Consulting and Clinical Psychology, 81, 761773. doi:10.1037/a0032871
Herbert, J.D., & Forman, E.M. (2013). Caution: The differences between CT and ACT may be larger (and smaller) than they appear. Behavior Therapy, 44, 218223. doi:/10.1016/j.beth.2009.09.005
Holowka, D.W., Dugas, M.J., Francis, K., & Laugesen, N. (2000, November). Measuring beliefs about worry: A psychometric evaluation of the Why Worry-II Questionnaire. Poster session presented at the annual convention of the Association for Advancement of Behavior Therapy, New Orleans, LA.
Jacobson, N.S., & Truax, P. (1991). Clinical significance: A statistical approach to defining meaningful change in psychotherapy research. Journal of Consulting and Clinical Psychology, 59 (1), 1219. doi:10.1037/0022-006X.59.1.12
Kazdin, A. (2002). Research design in clinical psychology (4th ed). Boston: Allyn & Bacon.
Kessler, R.C., Walters, E.E., & Wittchen, H.U. (2004). Epidemiology. In Heimberg, R.G., Turk, C.L., & Mennin, D.S. (Eds.), Generalized anxiety disorder: Advances in research and practice (pp. 2950). New York: Guilford.
Lovibond, S.H., & Lovibond, P.F. (1995). Manual for the Depression Anxiety Stress Scales (2nd ed.). Sydney, Australia: Psychology Foundation.
McGrath, K.B., Forman, E.M., del Mar Cabiya, M., Hoffman, K.L., Marques, K., Moitra, E., & Zabell, J.A. (2005, November). Development and validation of the Drexel University ACT/CBT Therapist Adherence Rating Scale. Poster presented at the annual meeting of the Association for Behavior and Cognitive Therapies. Washington, DC.
Meyer, T.J., Miller, M.L., Metzger, R.L., & Borkovec, T.D. (1990). Development and validation of the Penn State Worry Questionnaire. Behaviour Research and Therapy, 28 (6), 487495.
Moher, D., Schulz, K.F., & Douglas, A. (2001). The CONSORT statement: Revised recommendations for improving the quality of reports of parallel-group randomised trials. The Journal of American Medical Association, 285 (15), 19811991. doi:10.1001/jama.285.15.1987
Molina, S., & Borkovec, T.D. (1994). The Penn State Worry Questionnaire: Psychometric properties and associated characteristics. In Davey, G. & Tallis, F. (Eds.), Worrying: Perspectives on theory, assessment and treatment (pp. 265283). New York: Wiley.
Newman, M.G., Castonguay, L.G., Borkovec, T.D., Fisher, A.J., & Nordberg, S.S. (2008). An open trial of integrative therapy for generalized anxiety disorder. Psychotherapy: Theory, Research, Practice, Training, 45 (2), 135147. doi:10.1037/0033-3204.45.2.135
Öst, L-.G. (2008). Efficacy of the third wave of behavioral therapies: A systematic review and meta-analysis. Behaviour Research and Therapy, 46, 296321. doi:10.1016/j.brat.2007.12.005
Powers, M.B., Zum Vörde Sive Vörding, M.A., & Emmelkamp, P.M. G. (2009). Acceptance and commitment therapy: A meta-analytic review. Psychotherapy and Psychosomatics, 78 (2), 7380. doi:10.1159/000190790
Roemer, L., & Orsillo, S.M. (2005). An acceptance-based behavior therapy for generalized anxiety disorder. In Orsillo, S.M. & Roemer, L. (Eds.), Acceptance and mindfulness based approaches to anxiety: Conceptuallization and treatment (pp. 213240). New York: Springer Science and Business Media.
Roemer, L., & Orsillo, S.M. (2007). An open trial of an acceptance-based behavior therapy for generalized anxiety disorder. Behavior Therapy, 38 (1), 7285. doi:10.1016/j.beth.2006.04.004
Roemer, L., Orsillo, S.M., & Salters-Pedneault, K. (2008). Efficacy of an acceptance-based behavior therapy for generalized anxiety disorder: Evaluation in a randomized controlled trial. Journal of Consulting and Clinical Psychology, 76 (6), 10831089. doi:10.1037/a0012720
Sexton, K.A., & Dugas, M.J. (2008). The Cognitive Avoidance Questionnaire: Validation of the English translation. Journal of Anxiety Disorders, 22 (3), 355370. doi:10.1016/j.janxdis.2007.04.00
Westen, D., & Morrison, K. (2001). A multidimensional meta-analysis of treatment for depression, panic, and generalized anxiety disorder: An empirical exemination of the status of empiricaly supported therapies. Journal of Consulting and Clinical Psychology, 69, 875899.
Wetherell, J.L., Liu, L., Patterson, T.L., Afari, N., Ayers, C.R., Thorp, S.R., . . . Petkus, A.J. (2011). Acceptance and commitment therapy for generalized anxiety disorder in older adults: A preliminary report. Behavior Therapy, 42 (1), 127134. doi: 10.1016/j.beth.2010.07.002
Wittchen, H.-U., & Hoyer, J. (2001). Generalized anxiety disorder: Nature and course.Journal of Clinical Psychiatry, 62, 1519.
Yonkers, K.A., Warshaw, M.G., Massion, A.O., & Keller, M.B. (1996). Phenomenology and course of generalised anxiety disorder. The British Journal of Psychiatry, 168, 308313.
Zinbarg, R.E., Craske, M.G., Barlow, D.H., & O’Leary, T. (1993). Mastery of your anxiety and worry, therapist guide. San Antonio, TX: Psychological Corporation.
Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

Behaviour Change
  • ISSN: 0813-4839
  • EISSN: 2049-7768
  • URL: /core/journals/behaviour-change
Please enter your name
Please enter a valid email address
Who would you like to send this to? *



Altmetric attention score

Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed