Research shows that mindfulness-based meditation is associated with significant changes in gray matter density in areas of the brain associated with self-reflection, learning, stress, and emotions.
In 2011, a team of researchers took a group of 16 individuals through 8 weeks of a mindfulness-based meditation program. Their goal was to investigate how meditation affects the size and density of gray matter (brain tissue), a phenomenon that has been observed in earlier research. The program included weekly meditation meetings and audio recordings for guided practice. On average, participants reported 27 minutes of mindfulness exercises each day.
After comparing magnetic resonance images of the meditators' brains before and after the 8-week study, the researchers discovered several key areas of the brain had increased in density, including the cerebellum, posterior cingulate cortex, temporo-parietal junction, and hippocampus. These regions are involved in attention, planning, introspection, learning, and memory, among other things.
Additionally, the researchers observed reduced brain tissue density in an area of the brain called the amygdala, which influences fear, anxiety, and stress. These changes in the participants' brains were correlated with self-reported reductions in stress.
The study was published in Psychiatry Review: Neuroimaging.
While the study wasn't able to prove that meditation directly caused these changes in the brain, it does offer interesting insights into how and why meditation seems to have such a beneficial influence on a person's cognition and mood.
https://www.psychologytoday.com/us/blog/the-new-resilience/201502/how-meditation-changes-the-structure-your-brain
https://www.sciencedirect.com/science/article/abs/pii/S092549271000288X