Pain relief may be case of mind over matter

Placebos and strong painkillers activate the same areas of the brain, suggesting that pain relief can be a case of mind over matter.

Scandinavian researchers writing in the journal Science exposed volunteers to painful heat and took scans of their brains to see what happened when they received painkillers or placebo injections of salt water.

The salt water and a painkiller of the opioid family induced activity in the same region of the brain.

The results suggest that the brain has a built-in mechanism for dealing with pain, which may someday lead to the development of better drugs to treat pain.

Dr Martin Ingvar, of the Neurophysiology Research Group in Stockholm, Sweden, and colleagues there and in Finland exposed volunteers to painful heat and took scans of their brains.

Nine volunteers each had 12 scans.

The volunteers, who knew they were taking part in a pain study, had a heat probe taped to the backs of their hands. It could deliver anything from a warm glow to a 48-degree C near-burn.

The volunteers were told they would get two different injections for the pain, which led them to believe they were getting two drugs. In fact, they got a fast-acting narcotic, remifentanil, or plain saline.

While this was going on Dr Ingvar's team took positron emission tomography (PET) scans of each person's brains. PET scans can show brain-cell activity.

The drug and the placebo activated two areas of the brain - the rostral anterior cingular cortex and the brain stem.

"This indicated that we were able to get the same system spinning with the placebo and with the opioid," Dr Ingvar said.

What was unexpected was that the people who responded most strongly to the drug also responded most strongly to the placebo injection.

Dr Ingvar speculated that perhaps they had stronger pathways in the brain for pain relief.

It is known that different people perceive pain in different ways and at different intensities.

The pain test used by the group is meant to standardise this as much as possible.

Dr Ingvar hopes the findings will help researchers find better ways to treat pain.

Opioid drugs lose their effectiveness over time, causing patients to need larger and larger doses until they become addicted.

Pain is a valuable mechanism to warn that something is wrong, but once a person is aware of an injury, disease or damage and is taking care of it, pain loses its value.

The study fits in with similar research reported in January that showed depressed patients responded to placebos or anti-depressant drugs.

- REUTERS

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