Does Short-Term Mindfulness Meditation Change the Brain?
Does Short-Term Mindfulness Meditation Change the Brain?
Study finds no significant differences in brain structure between a group participating in an 8 week Mindfulness-Based Stress Reduction course compared to either control group.
It had been long thought that once formed, the brain is set in stone and cannot really change or alter its structure in any significant way. However, in the mid-twentieth century, in line with brain imagery developments, scientists started to find evidence that revealed that the brain is not static but can change and might be “plastic” in nature (Kalat, 2019). Researchers started to note how the brain, especially in our youth, has the ability to adapt and transform and, to a lesser degree, remains open to change throughout our lifespan (Kalat, 2019). This has been termed neuroplasticity, and how learning new skills like playing a musical instrument, physical exercise and solving puzzles an effect brain structure by increasing neural connectivity and grey matter density or volume (Colcombe et al., 2006; IIg et al., 2008; Kalat, 2019).
Mindfulness meditation is a skill that, when practised, is thought to help ground attention in emergent experience and reduce mind wandering, self-referential thinking, emotional reactivity and ruminative worry. Because of this, it had been long speculated that mindfulness meditation and potentially 8-week mindfulness-based interventions like mindfulness-based stress reduction and mindfulness-based cognitive therapy might have the potential to alter brain structure. Still, it was unclear if mindfulness meditation interventions had the potential to change the brain.
However, in 2011 a seminal study with over 2,800 citations by Holzel et al. reported that it found evidence that participation in a mindfulness-based stress reduction program increased grey matter density in brain areas like the left hippocampus, posterior cingulate cortex, the cerebellum, and the temporoparietal junction. Holzel et al. (2011) ultimately concluded that:
“Results suggest that participation in MBSR is associated with changes in grey matter concentration in brain regions involved in learning and memory processes, emotion regulation, self-referential processing, and perspective taking.” (p. 36)
This resulted in media hype with, for example, articles on Forbes, MailOnline, and The Washington Post, to name a few, on how in 8 weeks, mindfulness meditation can “change your brain”. This also resulted in more research studies being published on how mindfulness meditation can change brain structure (Fox et al., 2014).
Still, although these findings, researchers have also pointed out that these studies have numerous limitations that might have skewed results (Davidson & Kaszniak, 2015; Goldberg et al., 2017; Kriegeskorte et al., 2009; Van Dam et al., 2018). More recently, Kral et al. (2022) commented how,
Prior studies on MBSR-related changes in brain structure have marked limitations. These include a lack of active control groups and randomisation, reliance on circular analysis, and small sample sizes—methodological limitations that are prevalent in meditation research more broadly. (p. 1)
Noting this, Kral and colleagues conducted a study to assess more accurately for structural brain changes specific to mindfulness meditation by addressing these limitations:
By integrating a waitlist (WL) and a well-matched active control group with larger sample sizes (i.e., a minimum of 70 participants per group), in a set of two rigorous, randomised controlled trials (RCTs) with pre-post designs from which we created a combined dataset…………..to test for structural changes that were specific to mindfulness meditation training, rather than non-specific effects associated with well-being interventions more generally. (Kral et al., p. 1)
In total, the study recruited 218 healthy participants with no mental health difficulties who had never practised mindfulness meditation previously. At the start of the study, all these participants underwent a magnetic resonance imaging scan of their brains to have a picture of the structure of their brains before being randomly assigned to one of the study groups.
Being a randomised control trial, the study had three arms with 75 participants in the eight-week Mindfulness-Based Stress Reduction group, 73 participants in what is called an active control group doing a Health Enhancement Program, and 70 in what is called a waitlist control group which did not receive any type of training.
The study used the Health Enhancement Program course as an activity control because it was developed to be similar in structure to Mindfulness-Based Stress Reduction but does not include mindfulness training in it. Instead, the Health Enhancement Program uses activities like exercise, music therapy, and nutrition practices to replace mindfulness practices. This was done by Kral et al. (2022), so they could clearly identify if changes were because of mindfulness meditation.
So that if the Health Enhancement Program group would show no changes compared to the Mindfulness-Based Stress Reduction group. Therefore, these changes could be attributed to mindfulness meditation because mindfulness practice was the element missing in the Health Enhancement Program. While on the flip side, if the changes were non-specific and not attributable to mindfulness meditation, there would be no resulting difference between both groups.
At the end of the eight-week trial, participants took another magnetic resonance imaging scan to compare to the first one to see if any changes in brain structure could be detected. On analysis of the data, Kral et al. (2022) comment that they found:
No significant group differences for change in brain structure for Mindfulness-Based Stress Reduction compared to the Health Enhancement Program active control group, or the Waitlist control group, in the whole-brain analysis (including when controlling for the timing between scans). (p. 2)
Further, what is curious is that following the study, Kral et al. (2022) analysed participant’s self-reported levels of mindfulness using the Five Facet Mindfulness Questionnaire, and they observed how both the Mindfulness-Based Stress Reduction Group and the Health Enhancement Program group showed an increase in mindfulness with no significant difference between them compared to the waitlist control group.
This could show that improvements in self-reported mindfulness may not be solely related to mindfulness meditation practice but could also be influenced by other factors that might be in common between wellness interventions. This was also noted by a recent study which also observed how improvement from mindfulness interventions was not always a direct consequence of mindfulness meditation but sometimes because of other factors like group environment and the therapeutic alliance (Canby et al., 2021).
So, what does this indicate and what about previous studies that found evidence of structural changes?
The study’s authors raise an important point that finding results that contrast with previous research:
Highlights the importance of conceptual replications, it also raises new questions and highlights limitations of conceptual replications relative to direct replications. (Kral et al., p. 4)
What does this mean? Prior studies recruited participants seeking to do a Mindfulness-Based Stress Reduction program either because they were stressed or because of some other psychological difficulty; therefore, there was more “room” for change. While the current study controlled for these conditions and excluded participants with mental health difficulties from the study. Kral et al. (2022) commented because of this:
Participants in prior studies may have had more “room for improvement,” because they sought out a course for stress reduction, with some samples recruited specifically on the basis of the presence of high stress in participants the month before study participation. (p. 4)
Further, they note that because of the more rigorous experimental design used in the study, it might have effected the ecological validity of the study as the authors comment, “the simple act of choosing to enrol in MBSR may be associated with increased benefit” (Kral et al., 2022, p. 5)
Further to this, Kral et al. (2022) also note that mindfulness training targets a variety of psychological domains simultaneously, like attention, compassion, and emotion regulation. Because it engages a network of different brain regions and not specific ones, to varying degrees in different people and therefore it might make detecting overall changes at the group level difficult to observe.
This might be supported by the notion that studies of longer-term mindfulness interventions or studies that focused on a particular meditation practice usually lead to different results (citation).
So the results from Kral et al. (2022) study that short-term mindfulness did not change the brain does not mean that mindfulness meditation does not result in benefits or tangible changes. But as Goleman and Davidson (2017) point out, there as state changes from mindfulness practice and trait changes from mindfulness practice, and it might be that measurable permanent trait changes in behaviour and brain structure from mindfulness practice require a much longer time.
As ultimately also noted by the authors of the study Kral et al. (2022) commenting that:
“It may be that only with much longer duration of training, or training explicitly focused on a single form of practice, that structural alterations will be identified” (p. 5).
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