The brain changes that occur during adolescence may mean teenagers smokers are more likely to become seriously hooked than those who take up the habit as adults, suggests a new rat study.
Previous studies have suggested that the earlier someone starts smoking, the more likely they are to be life-long smokers and the more trouble they have in kicking their addiction, says Edward Levin, who led the study at the Duke University Medical Center in Durham, North Carolina, US.
Experiments to distinguish between the various possible causes could not ethically be conducted in humans. But when Levin and his team let teenage rats help themselves to nicotine, they found that female teen rats - at an age equivalent to 14-year-old girls - take twice as much as rats only exposed to nicotine in adulthood. And this insatiable use carries on when they grow up.
"The results indicate that early nicotine exposure can leave a lasting imprint on the brain," says Levin. "The brain continues to develop throughout the teenage years. Early nicotine use may cause the wiring of the brain to [develop] inappropriately."