FAITH can open your mind, but it can also cause your brain to shrink at a different rate, research suggests.
Researchers at Duke University Medical Centre in the US claim to have found a link between religious practices and changes in the brains of older adults.
The research, published in the journal Public Library of Science ONE, asked 268 people aged 58 to 84 about their faith, spiritual practices and life-changing religious experiences.
Changes in the volume of their hippocampus, the part of the brain associated with learning and memory, were tracked using MRI scans over two to eight years.
Protestants who did not identify themselves as born-again were found to have less atrophy in the hippocampus than born-again Protestants, Catholics or those with no religious affiliation.
Frequency of worship was not found to have a bearing on results, while participants who stated they had had a religious experience were found to have more atrophy than those who did not.
The brain tends to shrink with age but atrophy in the hippocampus has been linked with depression and Alzheimer's disease.
Study authors Amy Owen and David Hayward said the changes were not explained by other factors such as age, education, social support, depression or brain size that affected hippocampal atrophy. Other religious factors such as prayer, meditation or Bible study did not predict the changes. Dr Owen speculated stress could play a role - citing a higher level of atrophy among people from minority compared to mainstream religions.
''When you feel your beliefs and values are somewhat at odds with those of society … it may contribute to long-term stress that could have implications for the brain,'' he said.
The sample was largely drawn from Protestants from the south-east of the US.
Dr Haywood said other research indicated a new experience could be interpreted as comforting or stressful depending on if it fitted with existing beliefs. ''Several studies have found that … belonging to a religious group seems to be related to better health in later life, but not all religious people experience the same benefits,'' he said.