Hölzel, B K, Carmody, J, Vangel, M, Congleton, C, Yerramsetti, S M, Gard, T and Lazar, S W (2011),
Mindfulness practice leads to increases in regional brain gray matter density. Psychiatry Research, 191(1): 36–43
Psychology Being Investigated
Mindfulness Meditation – Central to this study is the practice of mindfulness meditation, which is grounded in the theory that focused, non-judgmental awareness of the present moment can lead to improved mental health and cognitive functioning. Mindfulness meditation, as a form of mental training, is theorized to induce changes in the brain through repeated practice.
Neuroplasticity – This is a foundational concept in the study. Neuroplasticity refers to the brain’s ability to reorganize itself by forming new neural connections throughout life. The study hypothesizes that mindfulness meditation can lead to changes in brain structures, indicating that the brain is not a static organ but is malleable and can be shaped by experiences, including meditative practices.
Stress Reduction and Psychological Well-being – The study explores how mindfulness-based interventions, like MBSR, can reduce stress and improve overall psychological health. This is based on the theory that mindfulness can alter one’s relationship to stressful events, thereby reducing the psychological impact of stress.
Brain Areas Associated with Mindfulness Practices – The focus on specific brain areas (like the hippocampus, PCC, TPJ, and cerebellum) is based on their known roles in functions such as memory, learning, emotional regulation, and self-referential processing. The theory suggests that changes in these areas might underlie the psychological benefits observed with mindfulness practices.
Background
Prior research in the field of mindfulness meditation has consistently highlighted its positive impact on psychological well-being. Studies have shown significant reductions in symptoms of stress, anxiety, and depression, alongside improvements in emotional regulation. This psychological benefit is not just confined to clinical populations; it extends to healthy individuals as well. Additionally, mindfulness practices have been linked to cognitive enhancements, including better attention, concentration, and working memory. These findings are particularly relevant in a society increasingly grappling with mental health challenges and cognitive overload.
On the neurobiological front, mindfulness meditation has been associated with structural and functional changes in the brain. Neuroimaging studies have revealed alterations in brain areas responsible for attention, emotion regulation, and self-awareness, such as increased gray matter density in the hippocampus and prefrontal cortex. This supports the concept of neuroplasticity, suggesting that the brain is adaptable and can be reshaped by experiences like meditation. Moreover, mindfulness has been shown to modify self-referential processing, which is believed to reduce tendencies towards rumination and excessive self-focus, common in mental health conditions like depression. These neurological changes underscore the tangible impact of mindfulness practices on the brain’s structure and function, reinforcing their potential as a tool for enhancing mental health and cognitive functioning.
Aims
- Investigate whether participation in an 8-week Mindfulness-Based Stress Reduction course (MBSR) could lead to changes in gray matter concentration in the brain.
- Identify brain regions that changed in association with participation in the MBSR course.
Procedure
The researchers used a method called voxel-based morphometry to measure changes in gray matter concentration in the brains of participants who completed an eight-week mindfulness-based stress reduction (MBSR) program.
Sample
The study included 18 healthy, right-handed individuals who were enrolled in the MBSR program. The participants were recruited from four MBSR courses held at the Center for Mindfulness at the University of Massachusetts Medical School. The courses included physician- and self-referred individuals from across New England who were seeking stress reduction.
The participants were included in the study if they self-reported as physically and psychologically healthy and not taking any medications. Further inclusion criteria were as follows: no meditation classes in the past 6 months, no more than four classes in the past 5 years, or 10 classes in their lifetime; 25 to 55 years old; no contraindications for MRI scanning (i.e., metallic implants, claustrophobia); commitment to attend all eight classes and perform the prescribed daily homework.
Methodology
The study used a pre-post design, meaning that the researchers measured gray matter concentration in the participants’ brains before and after they completed the MBSR program. The researchers also compared the participants’ brain scans to a control group of 17 individuals who did not complete the MBSR program.
The researchers used a variety of controls to ensure that any changes in gray matter concentration were due to the MBSR program and not other factors. For example, they made sure that the participants did not have any metallic implants or claustrophobia, which could affect the MRI scans. They also made sure that the participants did not have any other meditation experience in the past 6 months, no more than four classes in the past 5 years, or 10 classes in their lifetime.
The researchers collected data using MRI scans to measure gray matter concentration in the participants’ brains. They also collected demographic information about the participants, including age, gender, ethnicity, and education level.
Results
- Increase in Gray Matter Concentration in the Left Hippocampus: The MBSR group showed a significant increase in gray matter concentration in the left hippocampus compared to the control group.
- Whole Brain Analysis: Exploratory whole brain analysis revealed four clusters with significantly greater gray matter concentration at the post time-point compared to the pre time-point in the MBSR group. These regions include:
- Posterior Cingulate Cortex (PCC)
- Left Temporo-Parietal Junction (TPJ)
- Two clusters in the cerebellum (one in the cerebellar vermis and brainstem, and the other in the lateral parts of the posterior and flocculonodular lobe)
- Control Group Analysis: No significant changes in gray matter concentration were observed in the control group for these regions, except for a decrease in the PCC cluster.
The bar chart above shows the changes in brain gray matter concentration in various regions for the Mindfulness-Based Stress Reduction (MBSR) group compared to the control group.
Key Observations
- MBSR Group
- There were significant increases in gray matter concentration in all measured brain regions, including the left hippocampus, posterior cingulate cortex (PCC), left temporo-parietal junction (TPJ), cerebellar vermis/brainstem, and lateral cerebellum.
- Control Group
- No significant changes were observed in most regions, except for a decrease in gray matter concentration in the PCC.
Conclusion
Participation in an 8-week mindfulness-based stress reduction (MBSR) program was associated with changes in gray matter concentration in brain regions involved in learning and memory processes, emotion regulation, self-referential processing, and perspective taking. The study provides evidence that mindfulness practice can lead to changes in the brain that may have important implications for mental health and well-being. The study also suggests that mindfulness practice can lead to improvements in mindfulness subscales, such as acting with awareness, observing, and non-judging.
Strengths
- Use of a control group – One strength of the study is the use of a control group. The study included a control group of individuals who did not participate in the mindfulness-based stress reduction (MBSR) program. This allowed the researchers to compare changes in gray matter concentration between the MBSR group and the control group. The use of a control group strengthens the internal validity of the study by ruling out alternative explanations for the observed changes in gray matter concentration.
- Use of voxel-based morphometry – Another strength of the study is the use of voxel-based morphometry (VBM) to measure changes in gray matter concentration in the brain. VBM is a well-established method for measuring changes in gray matter concentration and has been used in numerous studies of mindfulness and meditation. The use of VBM strengthens the validity of the study’s findings by providing a reliable and objective measure of changes in gray matter concentration.
- Use of a standardized mindfulness program – A third strength of the study is the use of a standardized mindfulness program. The study used the mindfulness-based stress reduction (MBSR) program, which is a well-established and widely used mindfulness program. The use of a standardized program strengthens the external validity of the study by increasing the generalizability of the findings to other populations and settings. Additionally, the use of a standardized program allows for replication of the study’s findings by other researchers.
Weaknesses
- Small sample size – One weakness of the study is the small sample size. The study included only 18 participants who completed the mindfulness-based stress reduction (MBSR) program and 17 individuals in the control group. A small sample size reduces the generalizability of the study’s findings and increases the risk of Type II errors (i.e., failing to detect a true effect). A larger sample size would increase the statistical power of the study and improve the generalizability of the findings.
- Lack of randomisation – Another weakness of the study is the lack of randomization. The study did not use random assignment to assign participants to the MBSR group or the control group. Instead, participants were self-selected into the groups. This increases the risk of selection bias, which occurs when participants in one group differ systematically from participants in another group. A randomized design would have reduced the risk of selection bias and increased the internal validity of the study.
- Lack of blinding – A third weakness of the study is the lack of blinding. The researchers who conducted the study were not blinded to the group assignment of the participants. This increases the risk of experimenter bias, which occurs when the researchers’ expectations or beliefs influence the outcome of the study. Blinding the researchers to the group assignment of the participants would have reduced the risk of experimenter bias and increased the internal validity of the study.
Questions
1. What controls were implemented by the researchers to ensure the validity of their findings?
2. What limitations of the study could affect the generalisability of the findings?
3. How does the lack of blinding in the study impact its internal validity?
4. What measurement method did the researchers use to assess changes in gray matter concentration?
5. Reflect on the potential implications of the study’s findings for society as a whole. How might integrating mindfulness practices into various settings benefit individuals and communities?