Meditation diminishes activity in areas of the brain associated with mind-wandering, researchers found.

Compared with novice meditators, experienced study participants had significant deactivation in parts of the brain associated with the "default mode network" -- areas linked with attentional lapses and anxiety, Judson Brewer, MD, of Yale University, and colleagues reported in the Proceedings of the National Academy of Sciences.

Practiced meditators also reported less mind-wandering during meditation than did their less experienced counterparts, the researchers found.

Aside from attention lapses and anxiety, the "default mode network," or DMN, has also been associated with certain conditions, including ADHD and Alzheimer's disease. Conversely, mindfulness training has been shown to benefit certain conditions, such as pain, substance use disorders, anxiety, and depression.

So to assess whether mindfulness-based meditation can reduce activity along this brain axis, the researchers analyzed both experienced meditators and controls who'd never practiced the technique. The researchers used functional MRI to assess brain activation during both a resting state and a meditation period in 12 experienced mindfulness meditation practitioners and 13 controls.

Groups attempted three different types of meditation: concentration, loving-kindness, and choiceless awareness. Concentration is intended to prevent practitioners from engaging with their preoccupations; loving-kindness focuses on fostering acceptance; and choiceless awareness allows for focusing on whatever arises in the conscious field of awareness at any moment.

Brewer and colleagues found that experienced meditators reported less mind-wandering during meditation than did controls, which was true across groups.

At the same time, they generally saw less activation in the main nodes of the DMN -- the medial prefrontal cortex and the posterior cingulate corticies -- in experienced meditators than in controls.

While there was significantly less activation in the posterior cingulate cortex/precuneus and in the superior, middle, and medial temporal gyri and uncus, the trend toward diminished activation in the medial prefrontal cortex was not significant, they noted.

With regard to the specific types of meditation, the researchers found less activation in experienced meditators than in controls in the following regions:

• Concentration: posterior cingulate cortex, left angular gyrus
• Loving-kindness: posterior cingulate cortex, inferior parietal lobule, and inferior temporal gyrus extending into hippocampal formations, amygdala, and uncus
• Choiceless awareness: superior and medial temporal gyrus

When using the posterior cingulate cortex as a seed region, the researchers saw significant differences in connectivity patterns with several other brain regions, notably the dorsal anterior cingulate cortex, for experienced meditators compared with controls. And when using the medial prefrontal cortex as the seed region, they found increased connectivity with the fusiform gyrus, the inferior temporal and parahippocampal gyri, and the left posterior insula.

These patterns held during the resting-state baseline period as well, the researchers said, suggesting that meditation practice "may transform the resting-state experience into one that resembles a meditative state, and, as such, is a more present-centered default mode."

The researchers concluded that the overall results "support the hypothesis that alterations in the DMN are related to reduction in mind-wandering."

Though the study was limited by a small sample size, the researchers concluded that the findings may have a host of clinical implications, including treatment of conditions linked with dysfunction of these areas, such as ADHD or Alzheimer's disease.