'LIKE PUFFING ON COCAINE'

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.

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 show that there are long-lasting chemical changes," said
Michael Kuhar of Emory University in Atlanta.

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

A team led by Bruce Hope 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 the same thing 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 said.

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