Cognitive behavioral therapy seems to be less effective than it was in the 1970s, but researchers aren't sure why.

(Photo: Athanasia Nomikou/Shutterstock)

Since it was first developed, cognitive behavioral therapy (CBT) has seen its share of controversy. It's also become one of the go-to techniques for treating depression, anxiety, and some psychiatric disorders. But a new study questions whether it's still doing much good: It seems the benefits of CBT are in decline.

CBT emerged from a number of different traditions in academic psychology, and it's developed rapidly since the core ideas were first proposed in the 1960s and '70s. The foundational philosophy has stayed the same—negative thoughts about ourselves, the people around us, and the world in general help maintain "emotional distress and dysfunctional behavior," as Tom Johnsen and Oddgeir Friborg explain in Psychological Bulletin. But, over time, other researchers have modified and added to the original techniques in a variety of ways.

That, Johnsen and Friborg argue, should mean that as CBT evolves, its effectiveness correspondingly increases. When it comes to physical ailments, for example, "one always comes across new techniques and treatment methods, far better than their predecessors. Sometimes, the outcome for patients can improve in ways we only dreamt about 20 years ago," Johnsen, a clinical psychologist, writes in an email. "Observing this got me thinking whether the same evolutionary, beneficial process applied for psychotherapy."

One possibility is that once CBT became an established technique, less experienced—and therefore less effective—therapists began using it.

Still, Johnsen writes, he suspected CBT's effects weren't improving with time. That, he explains, was based on a quick look at a few recent studies that found the treatment's impact was about the same as it had been in the 1970s. To investigate, he and Friborg gathered 70 studies conducted between 1977 and 2014 that looked at how well CBT worked as a treatment for depression.

To their surprise, Johnsen and Friborg found that studies in the last few years reported CBT's impact on depression was about half of what studies in the late 1970s reported. The reasons for this disparity aren't entirely clear. Patient health and demographics, therapist experience, and even publication bias—across the sciences, the first results published often find substantial effects, while later studies find smaller effects—don't appear to be to blame.

One possibility is that once CBT became an established technique, less experienced—and therefore less effective—therapists began using it. In effect, then, CBT as it's actually practiced isn't as potent as it used to be. Another intriguing possibility is the placebo effect. There were high hopes for CBT in the 1970s, so patients back then may have been more optimistic than today's patients, who, thanks to the Internet, have easy access to less sanguine studies of CBT.

Johnsen writes that he hopes the research will "be a contributor when it comes to reversing the trend of declining treatment effects. On a personal level, I'm convinced there is potential for temporal improvement also for CBT and psychotherapy—finding the right keys, however, seems a complex and challenging issue."

Quick Studies is an award-winning series that sheds light on new research and discoveries that change the way we look at the world.