Meditation and brain growth

Friday May 15 2009

New research claims that “meditation could make you more intelligent as it boosts the size of your brain”, reported The Daily Telegraph . It said that research found that brain scans revealed “significantly larger” amounts of grey matter in long-term meditators.

This small study compared the brain anatomy of 22 people who meditated with 22 people who didn’t (controls). Although it did find some small differences in some parts of the brain, there were also many non-significant results. Overall brain size was not any larger in the meditators.

Importantly, the researchers themselves acknowledge that to establish if meditation actually causes changes in brain anatomy, it would be necessary to look at the brains of meditators and non-meditators over a period of time.

Where did the story come from?

The study was carried out by Dr Eileen Luders and colleagues from University of California, Los Angeles (UCLA) School of Medicine and the University of Jena. The research was funded by grants from the National Institutes of Health (NIH). The study was published in the peer-reviewed medical journal NeuroImage .

What kind of scientific study was this?

This brain imaging study investigated whether people who meditate have different brain anatomy to those who do not.

In total, 44 people were recruited to the study. The researchers recruited 25 active meditation practitioners through referrals and adverts at meditation venues. Three practitioners were excluded for having brain abnormalities, leaving 22 in the meditation group. This group was then matched for age and gender with 22 adults sourced through a database of normal adults called the International Consortium for Brain Mapping (ICBM).

All participants were free of neurological disorders. Those who meditated had been doing so for between five and 46 years and practised a variety of styles, including Zazen, Samatha and Vipassana. These styles have many practices in common, such as breath control, visualisation and attention to external and internal stimuli and events. Meditation time ranged from 10 to 90 minutes a session, with most meditators having daily sessions.

The researchers used magnetic resonance imaging (MRI) brain imaging to determine whether there were differences in overall brain volume, volume of grey matter and the volume of different brain regions. They used a technique called voxel-wise analysis, an approach applied to the analysis of brain images that permits an estimate of the volume of different brain structures.

The researchers give details of their approach to the brain imaging and mapping. In some of their analyses they take into account the fact that they made multiple comparisons between groups (which increases the risk of finding a positive result by chance) and also take into account the potentially confounding effects of age.

What were the results of the study?

The MRI scans showed a particularly large cluster of grey matter that occurred more frequently in the meditators than in the control group. The researchers describe this cluster as located “at the border between inferior and middle frontal gyrus and in approximate distance to Brodmann areas (BA) 11, 12 and 47”.

There was no difference between the groups in terms of total brain volume or total grey matter volume or in the volumes of the particular brain areas the researchers assessed (including left inferior temporal gyrus).

What interpretations did the researchers draw from these results?

The researchers conclude that larger volumes of grey matter in particular regions in the brains of meditators may account for “meditators’ singular abilities and habits to cultivate positive emotions, retain emotional stability, and engage in mindful behaviour”. They say that future “longitudinal analyses” (studies that follow people prospectively rather than examining them retrospectively) are needed to establish whether the link between meditation and brain anatomy is a causal one.

What does the NHS Knowledge Service make of this study?

As it stands, this small cross-sectional study cannot prove that meditating changes or “grows the brain” as The Daily Telegraph suggests. To prove or disprove this it would be necessary to carry out longitudinal studies that compared the brains of meditators and non-meditators over a period of time.

The researchers themselves conclude there were no differences between the groups in terms of “global cerebral measurements”, and that any effect that meditation might have on brain anatomy would be on a “relatively small scale”. This also means that any implication that meditators have larger brains overall is incorrect.

Further research would need to establish whether the association between meditation and brain anatomy is a causal one. Until then, it is not possible to attribute the small anatomical brain differences in this study to meditation.

Analysis by Bazian
Edited by NHS Choices