Smoking alters brain, says study
Smoking causes long-term changes in the brain associated with addiction similar to those in animals given cocaine and heroin, according to a US National Institute on Drug Abuse study. Previous studies have suggested that nicotine is at least as addictive as heroin, but this study indicates that the changes in the brain's neurons may account for the addiction, Reuters reports. Smokers (and even former smokers) had high levels of enzymes that help brain cells use chemical signals such as those made by message-carrying compounds called dopamine. Researchers say it's clear that the drugs cause the change.