Dr. Phil Noone @dr_philnoone 

 

Introduction

Mindfulness practice has existed for many centuries and has traditionally been associated with Eastern culture and spirituality (Siegel et al. 2008). From the mid-20^th century onwards, mindfulness became incorporated into psychological based interventions as a means of reducing psychological distress and enhancing well-being in clinical and non-clinical cohorts (Hofman & et al. 2010). In particular, the development of Mindfulness Based Stress Reduction (Kabat-Zinn 2003) and Mindfulness Based Cognitive Therapy (Segal et al. 2013), have been found to be beneficial in treating depression and anxiety (Hofman et al. 2010), post-traumatic stress disorder (King et al. 2013) and addiction (Chiesa 2014) in addition to enhancing well-being and quality of life (Carmody & Baer 2008). The neuroscience of mindfulness offers the potential to show how mindfulness practice can alter brain structure and function (Tang et al. 2015). Yet, within this area of new and emerging research, methodological shortcomings exist that point to a need for caution and a critical review of study outcomes. More rigorous and objective research is needed to gain a fuller picture of how neuroimaging can potentially enhance our understanding of mindfulness practice.

What is Mindfulness?

Mindfulness is described as cultivating increased awareness in the present moment that is non-judgmental, leading to greater acceptance of self (Kabit-Zinn 2013). Currently, no clear definition exists for mindfulness practice and in research studies it is often used interchangeably with acceptance and commitment therapy (Hayes et al. 2016); yoga and mantra meditation which may operate very different distinct neural mechanisms than mindfulness practice. In addition, definitions of mindfulness used in the literature do not make a distinction between dispositional mindfulness (the ability to pay attention mindfully to one’s surrounding) and intentional mindfulness (deliberate practice). This causes difficulty when comparing the effectiveness of mindfulness. Clear definitions are needed in order to understand psychological and neurological differences between these two groups and the effectiveness of mindfulness training (Wheeler et al. 2017).

Evidence from a meta-analysis conducted by Hofmann et al. (2010) based on 39 studies, involving 1,140 participants practicing mindfulness mediation for anxiety disorders, depression, cancer and a variety of other medical conditions indicates positive results. When effect size was calculated, it showed that Mindfulness based interventions was moderately effective for improving anxiety and mood symptoms (Hedges g =0.63) and in patients with mood and anxiety disorders effect size was Hedges g = 0.95). These findings were significant for the effectiveness of mindfulness interventions in treating anxiety and mood disorders. Whereas previous research focused on the effect of mindfulness practice on psychological health and well-being (Chiesa et al. 2011), a new and emerging area of neuroscience exists.

Neuroscience of Mindfulness

Recent advances in neuroimaging studies are able to explore neural mechanisms involved in mindfulness meditation practices using electroencephalography (EEG), functional magnetic resonance imaging (fMRI) and MRI scans (Holzel et al. 2011). Lazar et al (2005) in a review of cross sectional studies showed that different gray matter was identified in several brain areas of meditators compared with non-meditators, such as the hippocampus, known for learning and memory and emotional control (Holzel et al. 2007) and the insula which has a role in the process of awareness (Farb et al. 2007). However, a limitation of these studies involves the use of cross sectional designs which preclude causality.

A meta-analysis was conducted by Fox et al. (2014) to address whether meditation is associated with altered brain structure. This study meta-analysed 123 brain morphology differences from 21 neuroimaging studies using 300 meditation practitioners. Results identified eight brain regions that showed difference in meditators in comparison to controls, including body awareness (cortex and insular), memory (hippocampus), emotional regulation (anterior cortex). The effect size showed a global medium effect size but issues of publication bias and methodological limitations were raised as concerns. Fox et al. (2016) expanded further on this information by reviewing 75 studies that used different mindfulness styles such as focused attention, mindfulness meditation to show functional brain images and structural and functional neurologic changes. But, as suggested by Fox et al. (2016) there is a need to connect these neuroscience findings to the clinical and behavioral outcomes experienced by subjects involved in mindfulness interventions. This suggests that even when neuroscience can show structural and functional brain changes this is not sufficient unless accompanied by observation of behavioral changes.

Many of the studies conducted were cross sectional which involved comparing one group of meditators with a control group at one point in time. Many studies revealed differences in brain structure and function associated with the practice of mindfulness. Yet, the differences could be explained by pre-existing differences in the brains of study subjects or to group training induced effects. In a review study on neuroscience of mindfulness, Wheeler et al. (2017) conclude that different aspect of mindfulness were addressed in studies and that it is not possible to determine if dispositional mindfulness might exist intrinsically to the person and not be as a result of mindfulness practice. No clear distinctions are provided between dispositional mindfulness and engagement in formal or informal learned practice, such as walking mindful movement. For any meaningful discussion of the neuroscience of mindfulness and its aid or otherwise in our understanding of mindfulness practice, it is first necessary to have a clear definition of what is being investigated by mindfulness. By not making explicit a definition of mindfulness, evaluating the impact of mindfulness practice is difficult.

Holzel et al. (2010) suggest that despite attempts to investigate the brain regions that are structurally impacted by meditation practices these changes on their own are insufficient until they are accompanied by evidence of how mindfulness practice impacts on behavioral change. To date, according to Holzel et al. (2010) very few studies relate findings from neuroscience to self-reported behavioral measures. To address this situation, Holzel et al. (2011) conducted a controlled longitudinal study to investigate if grey matter density altered pre-post participation in Mindfulness Based Stress Release progamme. A sample of 16 naïve-meditation participants were tested using magnetic resonance imaging before and after they completed their 8 week programme. These results were compared with a waiting list control group, consisting of 17 participants. Findings indicated that participation in MBSR programme was associated in changes in brain grey matter in regions that are involved in learning, emotional regulation, memory processes and awareness. However, it should be noted that some of the positive benefits of attending the MBSR programme, such as group social interaction may have impacted the results. Findings must also be treated with caution due to the small sample size and the use of physician and self-referred participants seeking stress reduction. Of importance is that it highlights the brain structure is responsive to mindfulness meditation and that the nervous system has the capacity for plasticity. How this applies to emotional regulation is explored next.

Mindfulness and Emotional Regulation

Emotional regulation is described as conscious or unconscious actions that an individual exerts on the expression, timing and experience of emotions (Gross 1998). They are an adaptive response to environmental stimuli but can be maladaptive if used in the wrong context and with incorrect intensity. It has been suggested that mindfulness practice is influential in emotional regulation (Chambers et al. 2009). A survey of research on the neuroscience of mindfulness was conducted by Wheeler et al. (2017), with the aim of uncovering if similar brain pathways were activated using emotional regulation and mindfulness. When they reviewed the neuroscience on emotional regulation, areas of brain activation included anterior cortex, insular cortex, prefrontal cortex and deactivation of the amygdala. When they reviewed research on the neuroscience of mindfulness, areas of brain activation included prefrontal cortex, anterior cortex, insular cortex. But less deactivation was shown in the amygdala of participants from the dispositional mindfulness than those who engaged in intentional mindfulness. When intentional mindfulness was compared with control groups, those participating in intentional Mindfulness showed more emotional regulation. This review of neuroscience of mindfulness helps explain how mindfulness practice can alter the brain structure and function in a way that enhances present moment focus and facilitates emotional regulation. This review points to the importance of controlling for confounding variables such as education, socio-economic status and gender. Importantly, as suggested by Wheeler et al. (2017) individual who engage in mindfulness may also make different lifestyle choices than control groups and many research designs do not employ random assignment to groups under investigation.

Gotink et al. (2016) conducted a comparative study, with the aim of comparing the brain changes associated with an 8 week Mindfulness Based Stress Reduction (MBSR) and Mindfulness Based Cognitive Therapy (MBCT) programmes using functional magnetic resonance imaging. Findings indicated that the prefrontal cortex, the insula and the hippocampus showed increased activity, whereas, the amygdala showed decreased functional activity which is consistent with enhanced emotional regulation.

These findings, coupled with earlier research, bode well for the positive impact of mindfulness on health and well-being. The neuroscience of mindfulness has the potential to build on this body of work, using larger samples, and more randomized control trials.

Methodological Issues

Some of the methodological issues addressed in the literature include publication bias and researcher bias. Tang et al. (2015) suggest that many researchers are meditation practitioners, which poses questions over study outcomes. In addition, many studies have a strongly positive publication bias where only studies with positive results are mainly published (Fox et al. 2014) In addition, there are few longitudinal studies and sample sizes are generally small, with studies rarely replicated. This needs to be addressed.

Conclusion

In conclusion, I argue that having reviewed a limited section of literature on this growing and emerging topic, neuroscience can be said to provide some evidence of the impact of mindfulness on brain structure and function. Yet, much needs to be done. There is a need, for example, for clinical psychology and neuroscience to carry out research that integrates both forms of evidence into a theoretical framework that defines mindfulness. The ambiguity regarding what is subsumed under the rubric of ‘mindfulness’ has resulted in confusion in the literature because the specific mindfulness practice used is not always defined or operationalized.

An important issue relates to cost. Neuroscience is an expensive area to research and studies need to be replicated in order to provide robust evidence. Or maybe, the most important element in mindfulness practice is the transformation in our own lives. Neuroscience can help convince the scientific community of the impact of mindfulness but perhaps what is really needed going forward is for the lived experience of mindfulness practitioners to be narrated using qualitative research. As Siegel et al. (2009) point out, to truly understand mindfulness we have to experience it directly. My personal opinion is that cultivating mindfulness will remain a deeply personal, transformative journey of discovery, a ‘coming home’ to self and perhaps neuroscience remains somewhat limited in this human-space of ‘being’.

 

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