Review of trials comparing depression therapies ACT and CBT may indicate CBT's superiority

A new study from psychologists at the University of Kansas gauges the quality of the evidence from more than 500 randomized controlled trials of a common treatment for depression, acceptance and commitment therapy (ACT).

The research confirms evidence for ACT is "credible" when compared to weak control groups (for example, when ACT is compared with those on a waitlist who receive no treatment at all). But other key findings appearing in the journal Behavior Therapy are less clear about the efficacy of the therapy, including:

• When comparing ACT with other psychotherapies, the trials were often too small to credibly indicate superiority of any treatment over the other.
• When compared to traditional cognitive behavioral therapy (CBT), the evidence that existed suggested credible superiority for CBT. But, again, the trials were often too small to draw firm conclusions.

"There have been questions in the last decade or so about the credibility of findings in science broadly, including in psychology, and we've been interested in questions about how credible the research findings are for different forms of psychotherapy," said lead author Alex Williams, program director of psychology at the Edwards Campus of the University of Kansas.

"We've taken to evaluating quantitatively the credibility of bodies of research in psychology about different forms of therapy. This paper is an in-depth look at acceptance and commitment therapy—where we thought, 'Let's find every article we can about it.'"

Developed in the 1980s, ACT's mindfulness-centered approach has grown in popularity. Today, thousands of practicing psychotherapists offer ACT to clients, while the Department of Veterans Affairs recognizes ACT as an evidence-based therapy for depression. While ACT is considered a form of cognitive behavioral therapy, it differs from traditional CBT in several respects.

"Traditional cognitive behavioral therapy is focused on reframing your thoughts," Williams said.

"So, if you're depressed and you have thoughts about how bad your life is or how bad you are as a person, it's focused on helping you develop an alternative, more helpful and accurate thought. But ACT is less focused on changing your mind about the thought and more about accepting that thought and detaching from it. ACT also is focused on helping you take actions congruent with your values in life—there's more of an emphasis on it in ACT than traditional CBT."

However, poring over randomized control trials of ACT's efficacy, the authors found concerning signs regarding credibility (for example, too few participants in the studies to draw conclusions from them). In part, this stems from a lack of financial support in recent decades for up-to-date studies of depression therapies that use modern research and statistical methods.

"This area has been woefully underfunded forever," said co-author Eugene Botanov of Pennsylvania State University-York. "Now, the only people really funding it is the federal government, but they're not really interested in funding randomized control trials for depression or anxiety because we had so much research starting in the 1970s."

"But we know the world now a little differently than we did 50 years ago. Those studies were great for their time—they're just not so strong now. We need more high-quality studies to really understand which of the possibly effective treatments work better than others."

Indeed, this lack of strong evidence in studies that directly compare ACT with other treatments, like CBT, has resulted in "ambiguous evidence" that makes drawing definitive conclusions difficult, according to the authors.

"We found with ACT, when compared to traditional cognitive behavioral therapy in treating depression, it was really hard to credibly know, 'Is one better than the other?'" Williams said.

"But to the extent that there was signal among that noise, the indications were that CBT is superior as a depression treatment. You could take away from our paper that the best-case scenario for ACT compared to CBT is you throw your hands up and say, 'Nobody can know.' But there's no real way you could look at the paper and say, 'Oh, ACT is probably better than CBT at treating depression.'"

Williams and Botanov's co-authors were KU graduate students Annaleis Giovanetti, Victoria Perko and Westley Youngren, along with Carrie Sutherland of Avila University and John Sakaluk of the University of Western Ontario.

The researchers said more reliable trial results would make it easier for patients, therapists and organizations to know which treatments are best. According to the National Institute of Mental Health, 8.4% of all U.S. adults had at least one major depressive episode in 2020.

"These findings matter if we're therapists or patients or clients considering which treatments to use, or agencies that have concerns about what treatments to fund," Williams said. "Our paper suggests there's a lot of work to do to develop more credible evidence, one way or another, about the efficacy of ACT."

That ACT stacks up well against no treatment or a placebo treatment isn't a compelling enough case for funding or endorsing the therapy, according to Botanov.

"When we're looking at weak control groups in studies of ACT, like receiving ACT compared to no therapy at all, those studies do fairly well," he said. "But really, we don't care so much about ACT versus 'no treatment.' We care about, 'Should we advise a person to get traditional CBT or ACT for their depression?' If I'm the Veterans Administration or a university, and I want to hire therapists—which therapy should I be looking for, or training my therapists to do? We need better clinical trials to help us know."