Mindfulness Doesn’t Change Our Brains in Ways Once Thought

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In the late 1970s, Jon Kabat-Zinn developed an eight-week Mindfulness-Based Stress Reduction (MBSR) program. Although MBSR is still considered an effective technique for reducing stress, coping with generalized anxiety disorder, managing pain, and improving overall emotion regulation, new research suggests that eight weeks of MBSR does not change brain structure, as some previous studies have suggested.

The latest research (Kral et al., 2022) into whether eight weeks of MBSR causes structural brain changes in gray matter or cortical thickness combined datasets from two large, three-arm randomized controlled trials involving hundreds (n = 218) of meditation-naïve participants who had MRI brain scans at baseline and after the eight-week intervention period.

These findings, by first author Tammi Kral, senior author Richard Davidson, and colleagues at the University of Wisconsin-Madison's Center for Healthy Minds, were published on May 20 in the peer-reviewed journal Science Advances.

"[Previous] findings from a few small studies have permeated popular media with the notion that a few weeks of training in MBSR can lead to measurable changes in brain structure and have been cited over 3,200 times combined," the authors note in their paper's introduction.

For more on how mindfulness became a craze that's been overhyped, while its potential downsides are often overlooked, see here, here, and here.

Short-Term MBSR Does Not Change Brain Structure

After assessing gray matter volume (GMV), gray matter density (GMD), and cortical thickness (CT) at baseline and after eight weeks, Davidson's team was unable to replicate previous research studies purporting that short-term mindfulness training changes brain structure.

"In the largest and most rigorously controlled study to date, we failed to replicate prior findings and found no evidence that MBSR produced neuroplastic changes compared to either control group, at either the whole-brain level or in regions of interest drawn from prior MBSR studies," Kral et al. explain.

Based on these findings, the researchers speculate that "interventions lasting longer than the standard 8-week MBSR course" or "singularly focused on one specific meditation practice" may be required for mindfulness or meditation practice to change brain structure.

Previous MBSR-Related Brain Structure Studies Had Limitations

According to the authors, previous studies on MBSR-related changes in brain structure after eight weeks of mindfulness training had significant limitations, such as small sample sizes, a lack of active control groups or randomization, and reliance on circular analysis.

Notably, before Davidson and his team started their latest randomized controlled trials, they hypothesized that the amount of time someone spent practicing MBSR would be associated with structural brain changes in GMV, GMD, and CT. However, they could not replicate and expand on previous research but published their findings nonetheless.

This is noteworthy because negative research findings that don't support a hypothesis are often swept under the carpet or stashed away in a filing cabinet, where they remain unpublished. As part of the replication crisis, the so-called "File Drawer Problem" can perpetuate misinformation because the scientific community and public usually don't hear about studies that have null results or fail to replicate previous findings.

"As more research is conducted on [mindfulness meditation], the importance of reporting results of conceptual and direct replication attempts should be emphasized considering known publication bias for positive findings," Kral et al. write.

The latest (2022) paper by Richard Davidson and colleagues at the Center for Healthy Minds recommends that future research should examine "individual differences in engagement and efficacy of MBSR" and investigate the optimal "dose" (duration/frequency) of mindfulness training or meditation practice for best results.

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"We are still in the early stages of research on the effects of meditation training on the brain, and there is much to be discovered," Davidson said in a May 2022 news release.