Teens who tried cigarettes got hooked within weeks of starting -- a surprising result that contradicts the common wisdom that it takes years to become addicted, researchers said Wednesday.
And it only took a few cigarettes a day to get them dependent on nicotine, the international team of researchers found.
"I expected that some kids would get hooked quickly, but I thought that the average kid would have to smoke for a few years to get hooked," Dr. Joseph DiFranza of the University of Massachusetts, whose study is published in the September issue of the journal Tobacco Control, said in a statement.
"I thought that kids who got hooked quickly would be the exception to the rule. As it turned out, the kids who did not get hooked quickly were the exception," he added.
"This study has overturned a lot of conventional wisdom."
It only took an average of three weeks for a teen-age girl to become addicted to tobacco, even if she smoked only occasionally, the study found. Half of all boys who got hooked were firmly addicted within six months.
"Some of the kids it was love at first sight. They had one cigarette and they knew it was something they were going to do for the rest of their lives," DiFranza said in a telephone interview.
Scientists already know that addiction to smoking has a genetic component. Some people try cigarettes and never get hooked. The mechanism seems to be similar to that involved in addiction to drugs such as cocaine or heroin.
Some researchers also believe that, because the brains of adolescents are still developing, they can become addicted more quickly.
DiFranza's study, done with colleagues at Harvard University and the University of London, suggests this mechanism kicks in quickly in those predisposed to addiction. "For some people, nicotine is just what they have been waiting for," DiFranza said.
The teen smokers they studied were only smoking, on average, two cigarettes a day, one day a week.
Previous research has shown that it takes the average person who starts smoking as a teen-ager 18 years to break the habit for good.
The study, sponsored by the National Cancer Institute, involved 679 seventh-grade students, typically aged 12 and 13, who were followed for 30 months. The students were interviewed repeatedly.
Of them, 332 tried cigarettes or other forms of tobacco and of these 332, 40 percent showed some sign of addiction, including irritability, difficulty quitting and trouble concentrating without a cigarette.
Other research being published this week suggests that peer pressure can help teens stop smoking, just as it can persuade them to start.
Joan Tucker of the Rand Corporation in Santa Monica, California, and colleagues followed 278 male and 433 female smokers for five years beginning in their senior year of high school in 1990.
Writing in the September issue of Nicotine & Tobacco Research, they found that teens whose parents strongly disapproved of smoking were more likely to kick the habit, and those whose friends had quit were also more likely to quit.
Another study in Nicotine & Tobacco Research found that raising taxes on tobacco would discourage smoking and suggested a global policy calling for higher cigarette taxes could save the lives of more than 5 million smokers.
"Even with deliberately conservative assumptions, tax increases that would raise the real price of cigarettes by 10 percent worldwide would prevent between 5 million and 16 million tobacco-related deaths," said Dr. Kent Ranson of the London School of Hygiene and Tropical Medicine, who led the study.