BBC News' Pallab Ghosh: Fear can make pain worse

This is because the brain puts as much effort into anticipating potentially painful events as it does to creating the pain experience itself.

Scientists in Oxford and Canada have found areas in the brain which deal specifically with the expectation of pain. When those areas are stimulated they trigger fear or anxiety, causing mood swings or even behavioural changes.

Brain pain

Magnetic resonance imaging was used to monitor brain activity in volunteers as they felt a series of painlessly warm and painfully hot sensations in their left hands. Each sensation was signalled in advance by a coloured light.

The results showed that expecting pain caused activity in parts of the brain separate from, but close to, sites which dealt with the pain experience itself.

Brain activity causes fear and anxiety

The fact that our brains are "wired" this way could make good evolutionary sense, as it encourages us to avoid painful events.

Previous studies spotted the changes in brain activity, but assumed they were caused by the pain. The new research proves for the first time that it is instead linked to the anticipation of pain.

A better understanding of how the brain prepares the body for painful experiences could one day lead to new ways to help chronic pain sufferers control, if not the pain itself, the emotional trauma and disruption which comes with expecting the pain.