Upbeat people beat illnesses

By STEVE CONNOR

Scientists studying whether there is any truth in the notion of "mind over matter" have found that brain activity can control resistance to influenza.

For the first time, a direct link has been demonstrated between the brain's emotional state and the body's immune defences to explain why depressed people are more likely to catch a cold.

Although there is much research showing that a person's mood can influence his or her susceptibility to a virus, no previous study has found a direct link to the brain.

A team of neuroscientists led by Richard Davidson, of the University of Wisconsin at Madison, found that electrical activity in the left prefrontal cortex - the region of the brain above the left eye - seems to play a vital role in directing the body's immune system.

High levels of activity in this region of the brain are known to be linked with a more positive attitude to life - severely depressed people have a particularly subdued left prefrontal cortex relative to their right cortex.

Professor Davidson's team gave 52 volunteers psychological tests to gauge how emotionally positive they were in their general outlook on life.

Using a brain scanner, the scientists measured volunteers' electrical activity in both cortices before injecting them with a flu vaccine to see how well their immune systems responded to a simulated viral attack.

Over the next six months, the scientists monitored the levels of flu-fighting antibodies that appeared in the blood of each volunteer. Those with relatively high levels of activity in the left pre-frontal cortex produced many more antibodies.

"This study established that people with a pattern of brain activity that has been associated with a positive, affective style are also the ones to show the best response to the flu vaccine," Professor Davidson said.

"It begins to suggest a mechanism for why subjects with a more positive emotional disposition may be healthier."

The study is published in the Proceedings of the National Academy of Sciences.

Scientists have already demonstrated a link between pyschological wellbeing and physical health. Severe stress and depression are also known to affect chemical messengers called cytokines that are need to recover from an infection.

The study findings

* A brain region called the left prefrontal cortex seems to control the body's immune system.

* It is active in happy people and subdued in severely depressed people.

* A flu vaccine given to volunteers worked best on apparently happier people with high activity levels in this brain region.

* The result suggests you really are more likely to catch a cold if you are feeling emotionally low.

- INDEPENDENT