Meditation Increases Gray Matter Density in Brain Regions

Lillian Chang, AMFF
Jan 17
4 min read

A 2012 article titled "Mindfulness Practice Leads to Increases in Regional Brain Gray Matter Density," by Holzel et al., created a major positive response in both the academic medical community and the public health sector. It is a key scientific finding related to Mindfulness-Based Stress Reduction (MBSR). MBSR has become one of the most widely used meditation practices because it is generally known to have significant benefits for mental health. This research, more rigorously and specifically, discovered changes in brain gray matter density before and after MBSR practice, revealing an increase in gray matter density in the left hippocampus, posterior cingulate cortex, temporo-parietal junction, and cerebellum. The study indicates that practicing MBSR significantly increases the gray matter density in relevant brain areas, which improves our learning and memory processes, emotional regulation, self-emotion and information processing, as well as the ability to shift perspectives.

The study recruited 18 participants in the MBSR group and 17 participants in the control group, with participants matched for age and education level. The MBSR group participated in an eight-week program, with brain changes measured before and after the program through MRI scans, while the control group did not participate in the program. After filtering, 14 participants remained in each group.

The MBSR participants took part in weekly group sessions and a one-day course, mainly focusing on mindfulness practices such as body scans, mindful yoga, and sitting meditation to cultivate awareness of the present experience and a non-judgmental attitude. Participants also practiced mindfulness daily at home and integrated it into everyday activities such as eating, walking, or washing dishes. In class, in addition to formal practice, they addressed questions about daily mindfulness practices and learned how to use mindfulness to cope with stress. The participants were also taught how to record their home practice.

The researchers collected usable data from 14 MBSR participants and 14 control participants. The Five-Factor Mindfulness Questionnaire (FFMQ) was used, a 39-item scale designed to measure performance in five areas of mindfulness practice: observing (attending to or noticing internal and external stimuli such as sensations, emotions, cognitions, visual, auditory, and olfactory experiences), describing (labeling and describing these stimuli with words), acting with awareness (paying attention to one’s actions in the present moment rather than acting mindlessly or by habit), non-judging (avoiding judgment of one's feelings, thoughts, and emotions), and non-reactivity (allowing thoughts and emotions to come and go without reacting or interfering). Participants responded on a 1-5 scale (1 = never or very rarely, 5 = often or always).

During the 8-week MBSR course, participants engaged in an average of 22.6 hours of formal mindfulness practice. Despite significant differences in the practice time for body scans, yoga, and sitting meditation, these did not significantly affect the main research topics. The MBSR group showed significant improvements in three scale parameters (acting with awareness, observing, and non-judging), while the control group showed no significant changes. Gray matter analysis revealed that the MBSR group showed a significant increase in gray matter density in several regions, including the left hippocampus, posterior cingulate cortex (PCC), left temporo-parietal junction (TPJ), and cerebellum, which showed structural changes. No changes were observed in the control group.

The Hippocampus Plays a Central Role in Emotional Regulation, and Its Connectivity with the Insula, TPJ, and PCC

The hippocampus plays a core role in emotional regulation, while the insula is associated with inner sensations and awareness of the self. The temporo-parietal junction (TPJ) is involved in self-awareness and social cognition, such as our empathy and self-recognition. The posterior cingulate cortex (PCC) processes self-evaluation and emotions. When these areas are repeatedly activated through practice, structural changes can occur. The hippocampus, TPJ, and PCC form a brain network that assists in self-projection, and this network may be foundational to the changes in self-awareness seen in meditation practices.

In other words, the research found that MBSR participants showed significant structural changes in the cerebellum, brainstem, and other regions related to emotional and cognitive regulation through mindfulness meditation practice. Specifically, changes were observed in the posterior cerebellum, small nodulus, and vermis. Additionally, areas in the brainstem, including the locus coeruleus and the pontine nuclei, also showed an increase in gray matter density. These morphological changes help explain the positive effects of meditation on emotional health, including improvements in anxiety, depression, sleep, and attention.

At the end of the article, scientists carefully pointed out that, since MBSR (Mindfulness-Based Stress Reduction) is a group-based program, the observed positive effects could also stem from factors outside of meditation or mindfulness, such as group interaction, cognitive education about stress, or physical stretching exercises. For example, it is known that exercise can increase neurogenesis in the hippocampus, and the hippocampus plays a key role in long-term memory consolidation and learning. It can be said that the entire MBSR program collectively influenced the participants' brain structural changes.

In conclusion, the adult nervous system is plastic, and brain structure can change through training. The increase in gray matter density is due to the repeated activation of brain regions, and meditation is capable of achieving this activation.