SMOKING CHANGES BRAIN STRUCTURES, RESEARCHERS FIND

Washington: Smoking causes long-lasting changes in the brain -
similar to changes seen in animals when they are given cocaine,
heroin and other addictive drugs, US researchers said.

A study of the brain tissue of smokers and nonsmokers who had died
showed that smokers had the changes, even if they had quit years
before, the team at the National Institute on Drug Abuse reported.

"The data shows that there are long-lasting chemical changes in the
brains of humans," said Michael Kuhar of Emory University in Atlanta,
who was not involved in the study.

"The chemical changes alone suggest a physiological basis for
nicotine addiction."

A team led by Bruce Hope of Nida, one of the national Institutes of
Health, analysed levels of two enzymes found inside brain cells known
as neurons.

These enzymes help the neurons use chemical signals such as those
made by the message-carrying compound dopamine.

Smokers and former smokers had high levels of these enzymes, the
researchers reported in the Journal of Neuroscience.

Hope said other studies had seen similar results in animals given
cocaine and heroin - and it was clear that the drugs were causing the effects.

"This strongly suggests that the similar changes observed in smokers
and former smokers contributed to their addiction," he added.

Experts on smoking have long said that nicotine is at least as
addictive as heroin.

The US Centres for Disease Control and Prevention estimates that
20.9% of all adults smoke in the United States. This adds up to 45
million people. And 23% of high-school pupils also smoke.