Spiritual practices are popular. 'Wellness tourism', as trips to religious and secular retreats are called, is growing twice as fast as overall tourism, according to the Global Wellness Institute. The industry is worth many hundreds of millions of dollars.

Which raises a question. Is one type of meditation better than another? And further: how does Christian contemplation score?

The best studied area is mindfulness, a Buddhist form of meditation. Its popularity has been fueled by extensive scientific research. 'Mindfulness-Based Interventions have been shown to improve health outcomes in a wide range of clinical and non-clinical populations,' reports Mindful Nation UK, a study from the British Mindfulness All-Party Parliamentary Group.

Mindfulness has also been recommended for the treatment of depression by the British National Health Service since 2004. Overall, studies have demonstrated its help in alleviating stress, anxiety, depression and some psychosomatic conditions.

Christian traditions promote spiritual practices too. Christian retreats appear to be rising in popularity as well. But Buddhist meditation has long had a big advantage over Christian contemplation, because the latter hasn't been scientifically researched.

That is changing. In what is thought to be a first, researchers have investigated how Christian practices change the brain. A new study has examined the impact of a Christian retreat on 14 individuals, aged between 24 and 76. They were placed in brain scanners before and after a stay at the Jesuit Center in Wernersville, Pennsylvania.

For one week the individuals undertook the contemplative prayer practices designed by Saint Ignatius of Loyola, the founder of the Jesuits. The practices, known as the Spiritual Exercises, involve meditations such as imagining yourself as if present at events in the gospel stories. The results, though preliminary, show similar effects when compared with studies of Buddhist techniques.

The Christian meditators reported that their physical health improved, feelings of stress decreased and they also experienced an increased sense of the transcendent. The researchers also looked at changes to important neurotransmitters in the brain. Levels of dopamine indicated that the emotional depth of the participants was enhanced. Also altered were levels of serotonin, the neurotransmitter thought to contribute to feelings of wellbeing.

One participant found the experience transformative, saying it helped nurture a felt connection with God. 'Also, before the retreat, I would definitely say that I had a limited range of emotion, particularly not feeling very empathetic and not able to cry. But during the retreat, I felt the complete opposite and was much more in touch with a wide range of emotions.'

Another practitioner of the spiritual exercises came away realising they needed to 're-prioritize aspects of my life, particularly putting God and Spirit before work'.

'Thus, whether one evaluates the religious and spiritual literature or the scientific literature, there is substantial evidence of a relationship between positive emotions, including love and compassion, that are associated with spiritual practices such as those performed in the seven-day spiritual retreat in the current study,' the researchers conclude.

But what difference comes from belief in God and being a Christian? That is not, as yet, possible to discern scientifically.

One earlier study looked at meditating Carmelite nuns. It demonstrated that the sisters' reported mystical experiences of union with God did show up on brain scans. Those mystical experiences also seemed to be more powerful than, say, sharing with friends.

Father Christopher Krall, a Jesuit based at the University of Oxford, is addressing some of the theological questions. He presented his ideas at a recent conference on Science and Religion organised by the Ian Ramsey Centre of the University of Oxford and the International Society for Science and Religion. He believes that Christian meditation is fundamentally relational as it is about being open to God. It can develop human consciousness from basic modes of functionality, such as sensing surroundings, to higher modes that include perceiving good in the world and acting compassionately. 'Enriching consciousness can be fostered,' he explains. 'It can take us to the best we can be as humans.'

Future studies involving more people will be needed to develop these insights. For example, it is unclear what are the main 'active ingredients' in spiritual practices and retreats. Is it the practice of prayer or the sense of being in a spiritual place? There is also the question of how religious retreats differ from secular retreats, and whether going on holiday or being with a loved one might be equally transformative.

Christian spiritual practices are now becoming the object of scientific study. The Buddhists have a head start with mindfulness research. But expect more studies on the effects of prayer, contemplation and silence which Christians, like Buddhists, have been practising for thousands of years.

Mark Vernon is a psychotherapist. For more see www.markvernon.com