I don’t really have much in the way of scientific evidence for combining the two. I have, however, information from personal experience that many therapists tend to combine the two approaches with varying effects. I think the combination can be useful if a particular case conceptualisation is chosen and diverse techniques are utilized. (I believe this is called technical eclecticism).
Take for example, a disorder I have struggled with, Social anxiety Disorder. The CT model (1)of the disorder claims that it is maintained by maladaptive cognitions about performance on social situations and the social cost of social failure. These maladaptive cognitions lead to increased anxiety which triggers behavioral avoidance of uncomfortable situations which only maintains the anxiety. Based on this model, cognitions have to be modified in order for behavior to be changed.
According to ACT however (2), anxiety is maintained by a constant struggle with thoughts and feelings, and attachment to the literal meaning of thoughts and desire to avoid negative emotions. Thus behavioral avoidance is an extension of the desire to avoid negative experiences.
One therapist I had resolved the differences by focusing on the similarity - the behavioral component. My social anxiety was conceptualized as being maintained by behavioral avoidance. Thus, my thoughts and feelings were seen as barriers to countering that avoidance. In order to remove these barriers, she used cognitive restructuring and defusion as tools depending on the type of thought. In my experience, cognitive restructuring was most useful if there was a side of the issue that was being ignored or if i really believed the maladaptive thoughts. I found that defusion was most helpful for thoughts that hindered me even though I knew that they were untrue or that there was no way of knowing if they were true. For example, I often believed that my friends secretly did not like me and were not telling me this. The cognitive therapy approach is to label this thought as a distortion - mind reading - and attempt to come to a conclusion that can be logically come to based on the available evidence. I found this to be absolutely useless with the thought - because I was certain it was mind reading but it still held power over me. Defusion helped me to modify the power of the thought since I could not modify it. Over time, I discovered that it was helpful to me to do cognitive restructuring first to reduce the believability of a thought and then defuse the thought if I knew the logical truth but could not really believe it.
Another therapist I had helpfully illustrates the conflict with using diverse case conceptualisation. This therapist both suggested that using coping statements (realistic facts that could counter negative thoughts) was helpful and trying to decipher the real facts of a situation while in it was unhelpful which is very contradictory. He also used both ACT and CT conceptualisation in the most confusing ways. For example, he advised that mindfulness exercises not be utilized as ways to reduce anxiety but to reduce experiential avoidance (an ACT concept) yet he conceptualized exposures in the CT way, which stresses habituation and fear reduction rather than engaging in scary activities for valued living (ACT). He also stressed the importance of aiming for behavior change rather than having less anxiety (an ACT concept) yet he rated the subjective levels of distress while engaging in a task and considered an exposure a success once the distress had fallen. I think the problem was that he had taken a standard CBT social anxiety group therapy and thrown in ACT case conceptualisation without removing the elements from CBT that do not fit with the ACT approach. I was lucky that I had discovered how to use the differing strategies with the previous therapist I had. Otherwise, I would have been very confused. I don’t think any of the techniques would have negated each other - just that it would have been difficult for me to decide which technique was useful in which situation. This therapist was mostly helpful for me in teaching me the empirically supported social anxiety exposures - which happens to be largely the same for both therapies.
As an interesting side note, I later discovered I have Attention Deficit/Hyperactivity Disorder which affects me mostly when I have to sustain effort or attention on something I don’t want to do. For this problem, I have found CT to be useless because it involves telling me to do experiential experiments and to notice that I can do things well even if I have no motivation (3). The thing for me is that I know that but I still really don’t want to do the task and just won’t. Working with the second therapist in this issue was helpful because an ACT conceptualisation completely fit with the problems. And, since CBT doesn’t have a well-established protocol for ADHD, I did not have the same problems with a CBT protocol filtering in to an ACt therapy.
Clark, D. M. & Wells, A. (1995). A cognitive model of social phobia. In R. Heimberg, M. Liebowitz, D. A. Hope, & F. R. Schneier (Eds.), Social phobia: Diagnosis, assessment and treatment. (pp. 69–93). New York: Guilford Press.
Dalrymple K. L., and Herbert J. D. (2007) Acceptance and Commitment Therapy for Generalized Social Anxiety Disorder: A Pilot Study Behavior Modification Vol 31, Issue 5, pp. 543 - 568
Saulsman, L., & Nathan, P. (2008). Put Off Procrastinating. Perth, Western Australia: Centre for Clinical Interventions.