- Vowles, K. E., & McCracken, L. M. (2008). Acceptance and values-based action in chronic pain: A study of effectiveness and treatment process. Journal of Consulting and Clinical Psychology, 76, 397-407.
Participants included 171 completers of an interdisciplinary treatment program, 66.7% of whom completed a 3-month follow-up assessment as well. Results indicated significant improvements for pain, depression, pain-related anxiety, disability, medical visits, work status, and physical performance. Effect size statistics were uniformly medium or larger. According to reliable change analyses, 75.4% of patients demonstrated improvement in at least one key domain. Both acceptance of pain and values-based action improved, and increases in these processes were associated with improvements in the primary outcome domains.
- 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), 1-28.
101 heterogeneous outpatients reporting moderate to severe levels of anxiety or depression were randomly assigned either to traditional CT or to ACT. 23 junior therapists were used. Participants receiving CT and ACT evidenced large and equivalent improvements in depression, anxiety, functioning difficulties, quality of life, life satisfaction and clinician-rated functioning. “Observing” and “describing” one’s experiences mediated outcomes for those in the CT group relative to those in the ACT group, whereas “experiential avoidance,” “acting with awareness” and “acceptance” mediated outcomes for those in the ACT group.
- Lappalainen, R., Lehtonen, T., Skarp, E., Taubert, E., Ojanen, M., & Hayes, S. C. (2007). The impact of CBT and ACT models using psychology trainee therapists: A preliminary controlled effectiveness trial. Behavior Modification, 31(4), 488-511.
Randomized controlled study in which 14 student therapists treat one client each from an ACT model or a traditional CBT model for 6-8 sessions following a 2 session functional analysis. Participants with any normal outpatient problem were included. At post and at the 6 month follow up ACT clients are more improved on the SCL-90 and several other measures. Greater acceptance for ACT patients; great self-confidence for CBT patients. Both correlated with outcomes, but when partial correlations are calculated, only acceptance still relates to outcome.
- McCracken, L. M., Vowles, K. E., & Eccleston, C. (2005). Acceptance-based treatment for persons with complex, long standing chronic pain: A preliminary analysis of treatment outcome in comparison to a waiting phase. Behaviour Research and Therapy, 43, 1335-1346.
108 chronic pain patients with a long history of treatment are followed through an ACT-based 3-4 week residential treatment program. Measures improved from initial assessment to pre-treatment on average only 3% (average of 3.9 month wait), but improved on average 34% following treatment. 81% of these gains were retained through a 3 month follow up. Changes in acceptance predicted positive changes in depression, pain related anxiety, physical disability, psychosocial disability, and the ability to stand. Positive outcomes were also seen in a timed walk, decreased medical visits, daily rest due to pain, pain intensity, and decreased pain medication use.
- Strosahl, K. D., Hayes, S. C., Bergan, J., & Romano, P. (1998). Does field based training in behavior therapy improve clinical effectiveness? Evidence from the Acceptance and Commitment Therapy training project. Behavior Therapy, 29, 35-64.
Controlled effectiveness trial. Not randomized. Shows that training in ACT produces generally more effective clinicians, as measured by client outcomes.