Mindfulness Practice Leads to Increases in Regional Brain Gray Matter Density

 

Mindful meditation has been reported to produce positive effects that last beyond the time an individual is actually meditating. A large body of research has established the efficacy of these mindfulness-based interventions in reducing symptoms of a number of disorders, including anxiety, depression, substance abuse, eating disorders, and chronic pain. Meditation has also been associated with improving well-being and quality of life.

Researchers have begun to explore the mechanisms occurring during and as a result of mindfulness meditation practice with neuroimaging techniques such as EEG and MRI. Recently, several cross-sectional MRI studies have demonstrated that experienced meditators exhibit a different gray matter size and shape in multiple brain regions when compared to non-meditating individuals. This is significant because gray matter includes regions of the brain involved in muscle control, seeing, hearing, memory, emotions, speech, decision making, and self-control.1

 

Overall, the Mindfulness-Based Stress Reduction (MBSR) program was associated with increased gray matter in the brains of participants.2 In other studies, significant positive correlations have been found between gray matter volume in elderly persons and measures of memory.3

 

The purpose of the study described in this summary was to identify brain regions that changed in association with participation in an 8-week MBSR course. The goal of the group program was to improve participants’ mindfulness and well-being, and reduce their levels of perceived stress. The researchers were attempting to find objectively measurable neurological changes that could underlie the trait-changes associated with mindfulness practice. Changes in gray matter concentration were investigated, with focused analyses conducted for the hippocampus and insula. Then, exploratory analyses were performed on the entire brain and compared to a control group.

The MBSR study participants were recruited among patients enrolled in four MBSR courses held at the Center for Mindfulness at the University of Massachusetts Medical School.2 Patients were included in the study if: 1) they self-reported that they were physically and psychologically healthy and not taking any medications, 2) were 25 to 55 years old, 3) had no contra-indications for MRI scanning, 4) were willing to commit to attend all eight classes and perform the prescribed daily homework, and 5) were not participating in meditation classes in the past six months, no more than four classes in the past five years, or ten classes in their lifetime. In all, 18 healthy, right-handed individuals were enrolled in the study, 8 male and 10 female, with a mean age of: 37.89 years. Due to discomforts during the first MRI scanning session, two participants did not return for the second session resulting in a final study population of 6 male and 10 female participants with a mean age of 38.0 years and average education of 17.7 years.

The control group included 17 participants (11 male and 6 female) with a mean age of 39.0 years and an average of 17.3 years of education. The control and treatment groups did not significantly differ in age or education.

The MBSR program consisted of 8 weekly group meetings (2.5 hours each), plus one 6.5 hour meeting during the sixth week of the course. The mindfulness training exercises were aimed at developing awareness of present-moment experiences, and included a body scan, mindful yoga, and sitting meditation. During the body scan, participants were encouraged to direct attention sequentially through the entire body, observing the sensations in each region and ending with an awareness of the body “as a complete whole”. The yoga contained gentle stretching exercises and slow movements coordinated with the breath. Participants were encouraged to investigate what felt appropriate for themselves, and adapt in a non-judgmental way by honoring their body’s limitations. Sitting meditation practices typically began with awareness of breath, and evolved to include awareness of other things like sounds, sight, taste, other body sensations, thoughts and emotions. Finally, emphasis was eventually placed on open awareness meditation that expanded to include the awareness of one’s presence in the here and now.

Participants received 45-minute audio recordings of guided mindfulness exercises, which included body scan, yoga, and sitting meditation. They were told to play these recordings at home, as well as practice mindfulness in daily life activities such as eating, walking, washing the dishes, and taking a shower. When the participants were engaged in formal classes, the instructors also answered questions about how to practice mindfulness in everyday life and how to use mindfulness for coping with stress in daily life. The researchers reported that in the past MBSR participants have reported a wide range of home practice compliance. Therefore, they had study participants record daily the amount of time they spent engaged in mindfulness exercises.

Data were collected using the Five Facet Mindfulness Questionnaire, which is a 39-item scale to measure observing, describing, acting with awareness, non-judging of inner experience, and non-reactivity to inner experience. The responses were given on a 5-point scale (1 = never or very rarely true, 5 = very often or always true).

High-resolution MRI scans for program participants were conducted 2 weeks before (baseline) and after the program, and two scans approximately two months apart were also conducted on the controls. The researchers computed exploratory whole brain analyses as well as region of interest (were bilateral hippocampi and bilateral insulae) analyses.

The MBSR participants reported an average of 27 minutes per day of formal homework exercises over the 8-week course. This included body scan practice, yoga, and sitting meditation. MBSR participants significantly increased their mindfulness scores on three of the five subscales evaluated (acting with awareness, observing, and non-judging). Significant increases were found in these three areas for the MBSR participants, but not the control group.

The tests within the MBSR group identified a small cluster of increased gray matter concentration in the left hippocampus. There were not significant changes in the gray matter of the controls. The exploratory analyses found increased gray matter concentration in regions in the posterior cingulate cortex, left temporo-parietal junction, and cerebellum in the MBSR participants, but not the control group over the 8-week period. This finding suggests that participation in an MBSR course is associated with structural changes in these brain regions.

A limitation of the study is that the MBSR group program may have experienced some of the positive effects from components not specific to meditation or mindfulness, such as group social interaction, stress education, or gentle stretching exercises. For future research purposes, it is important to note that in this instance structural changes in these regions of the brain were detectable within eight weeks following a mindfulness training program. If MBSR participation can have a positive effect on gray matter in the brain, that increased gray matter may then be associated with improvements in memory. Similar research in patients with mild cognitive impairment or Alzheimer’s disease is warranted.

  1. Miller AK, Alston H, Corsellis Variation with age in the volumes of grey and white matter in the cerebral hemispheres of Man: Measurements with an image analyzer. Neuropathology and Applied Neurobiology. 2008; 6 (2): 119–132.
  2. Hölzel BK, Carmody J, Vangel M, et al. Mindfulness practice leads to increases in regional brain gray matter density. Journal of Psychiatry Research. 2011; 191(1): 36–43.
  3. Taki Y, Kinomura S, Sato K, et al. Correlation between gray/white matter volume and cognition in healthy elderly people. Brain and Cognition. 2011;75 (2): 170–176.

 

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