Meditation appears to help preserve the brain's grey matter, the tissue that contains neurons, says a new study from UCLA.

Looking specifically at the association between age and grey matter, they compared 50 people who meditated for years and 50 who did not.

While both showed loss of grey matter with ageing, the decline was slower in the meditating group.

Where most studies have focused on reasons for neuro-degeneration, this one sought to find a way to enhance cerebral health, says Dr Eileen Luders, first author and assistant professor of neurology at the David Geffen School of Medicine at UCLA.

Each group in the study was made up of 28 men and 22 women ranging in age from 24 to 77.

Those who meditated had been doing so for four to 46 years, with an average of 20 years.

The high-resolution magnetic resonance imaging showed that large parts of the gray matter in the brains of those who meditated seemed to be better preserved.

Dr Florian Kurth, a co-author of the study and postdoctoral fellow at the UCLA Brain Mapping Center, said the researchers were surprised by the magnitude of the difference.

"We expected rather small and distinct effects located in some of the regions that had previously been associated with meditating," he said. "Instead, what we actually observed was a widespread effect of meditation that encompassed regions throughout the entire brain."

The article appears in the current online edition of the journal Frontiers in Psychology.

With longer life expectancy comes the risk of losing mental functional abilities as the brain begins to lose its volume and weight.

Meditation could be one way to minimise those risks.

The researchers are hesitant to draw direct, causal connection as factors of lifestyle choices, personality traits, and genetic brain differences may also play a role.

Mindfulness meditation is particularly being studied and practised to treat problems like attention deficit, memory loss and depression as well as physiological diseases like blood pressure and weak immune system.

The psychological state of awareness of the present moment has turned from a mere 2,600-year-old Buddhist concept to mainstream psychotherapy.

Breast cancer survivors who practised mindfulness-based meditation daily for eight weeks have registered a healthy state of telomeres, the caps at the ends of chromosomes that protect the DNA.

Regular practice of meditation has been linked with lower anxiety, reduced respiration rates and other post-traumatic stress disorder symptoms.

It has been seen that mind-body techniques can switch on and off some genes linked to stress and immune function.

Neuro-imaging and genomics technology are mapping physiological changes accompanying meditation in greater detail.

A Harvard study two years ago published in PloS One showed that a session of relaxation-response practice was enough to enhance the expression of genes involved in energy metabolism and insulin secretion and reduce expression of genes linked to inflammatory response and stress.

Scientists at the University of California at Los Angeles and Nobel Prize winner Elizabeth Blackburn found that 12 minutes of daily yoga meditation for eight weeks increased telomerase activity by 43%.