Depression is not only the most common mental illness, it’s also one of the most tenacious. Up to 80 percent of people who experience a major depressive episode may relapse. Drugs may lose their effectiveness over time, if they work at all.

But a growing body of research is pointing to an intervention that appears to help prevent relapse by altering thought patterns without side effects: mindfulness-based cognitive therapy, or MBCT.

A new study on the approach to be published in a forthcoming issue of The Lancet found that MBCT helped prevent depression recurrence as effectively as maintenance antidepressant medication did. The study also found that MBCT had a larger effect on people with histories of more severe childhood abuse, which has been associated with a greater risk of relapse, than on participants overall. An “Evidence Map of Mindfulness” prepared for the Department of Veterans Affairs on all types of mindfulness interventions found the most consistent effect on depression versus other health conditions (Evidence-based Synthesis Program Center, 2014).

“People at risk for depression are dealing with a lot of negative thoughts, feelings and beliefs about themselves and this can easily slide into a depressive relapse,” says the Lancet study’s lead author, Willem Kuyken, PhD, a professor at the University of Oxford in the United Kingdom. “MBCT helps them to recognize that’s happening, engage with it in a different way and respond to it with equanimity and compassion.”

Growing evidence: 

The simplest definition of mindfulness is paying attention to one’s experience in the present moment. It involves observing thoughts and emotions from moment to moment without judging or becoming caught up in them. During a practice session, when the mind wanders, the meditator ideally takes note of where it goes, and calmly returns to the moment at hand, perhaps focusing on breath, bodily sensations or a simple yoga move.

Over a decade ago, three psychologists — Zindel Segal, PhD, J. Mark G. Williams, DPhil, and John Teasdale, PhD — developed MBCT. In particular, MBCT seeks to teach people to disengage from the deeply ingrained dysfunctional thoughts that are common with depression.

As currently designed, MBCT is an eight-week, group-based program that incorporates mindfulness exercises including yoga, body awareness and daily homework, such as eating or doing household chores, with full attention to what one is doing, moment by moment. The protocol derives from Jon Kabat-Zinn’s Mindfulness-Based Stress Reduction curriculum, and includes elements of cognitive-behavioral therapy (CBT) targeted to people with prior histories of depression.

Segal and colleagues studied 84 people in remission and found that MBCT could help prevent recurring depressive episodes as well as medication and better than placebo (JAMA Psychiatry, 2010). A review Madhav Goyal, MD, of The Johns Hopkins University wrote for JAMA Internal Medicine (2014) looked at different types of mindfulness meditation among 47 studies, finding that it had the same moderate effect on treating depression as medication, and had moderate effects on anxiety and pain as well.

Evidence also suggests that MBCT may be of more help to patients most vulnerable to relapse: People with a greater number of prior episodes or who had residual depressive symptoms. In a 2011 meta-analysis by Jacob Piet, PhD, and Esben Hougaard, PhD, of the University of Aarhus in Denmark in Clinical Psychology Review, MBCT was more effective in preventing relapse among people with three or more episodes, reducing risk by 43 percent versus 34 percent for participants overall.

In another study, Williams and colleagues found that participants who had depression at earlier ages, or who had more adversity or abuse in childhood, were more likely to benefit from MBCT (Journal of Consulting and Clinical Psychology, 2014). Kuyken, who led the Lancet study, speculates that these patients may be more motivated and invested in the treatment.

“They’ve been depressed more, they’ve had all these unpleasant things happening to them and they’ve often tried antidepressants and other kinds of therapy, so they’re willing to meditate 40 minutes a day and to do something quite different in terms of mindfulness practices like mindful movement,” he says. “Those who do best are those ready to engage fully.”

While evidence suggests mindfulness works to help prevent depression relapse, researchers don’t yet know how.

“It may be that mindfulness leads to an increase in self-compassion and a decrease in experiential avoidance,” says Stuart Eisendrath, MD, professor and head of the Depression Center at the University of California, San Francisco. “It may be selective attention — if you focus on your breath, you have less bandwidth to ruminate. There are a lot of factors that are operative and we’re just beginning to tease out and deconstruct them. It’s like tasting a soup with 10 spices. Is there one main ingredient or is the flavor a combination of things?”

For example, one characteristic of depression is a habit of thinking negatively about experience, one’s self or the future. Mindfulness trains people to be more aware of these thoughts and to stand back and simply observe their thoughts passing through their minds — ‘Oh, there I go again, calling myself an idiot’ — instead of trying to control their emotions. Or, in the case of people who have recovered from depression, blaming themselves for feeling down again or worrying about a relapse.

MBCT’s emphasis on cultivating awareness and acceptance of the present moment also seeks to harness ruminating and mind wandering, both of which are implicated in depression, says Stefan Hofmann, PhD, a Boston University professor whose lab studies anxiety and related disorders.

“Why worry about the future and ruminate about the past?” says Hofmann. “Live for the here and now. It’s comfortable. It’s the joyful experience of being alive.”

Researchers also mention that the group aspect of MBCT may help clients breach the wall of solitary shame and guilt that depression can build.

“By practicing with others, people realize that the way their minds generate depressive and ruminative thoughts is really no different from others, like that builder over there, or my neighbor. These are just thoughts — not facts in my life,” Kuyken says