The more time a child is exposed to a parent addicted to smoking, the more likely the youth will not only take up cigarettes but also become a heavy smoker.

So warns a team of researchers led by Georgetown Lombardi Comprehensive Cancer Center scientists in Pediatrics. The study, published online, is among the first to take a prospective, intergenerational view of the impact a parent's behavior has on smoking risk for their adolescent offspring.

The findings suggest that parental smoking cessation early in their children's lives is critical to prevent habitual smoking in the next generation.

"It is difficult to dissuade children from smoking if one or both parents are heavily dependent on cigarettes," says the study's lead investigator, Darren Mays, PhD, MPH, an assistant professor of oncology at Georgetown Lombardi. "It is also important for parents who smoke to know that their children may model the behavior, particularly if a parent is nicotine dependent."

Mays says nicotine dependence is characterized by strong cravings to smoke, needing more nicotine to feel the same effects and feeling discomfort (withdrawal) without the drug.

"Our study supports the need for pediatric clinics to be vigilant about the smoking habits of their patients and their patients' parents," Mays adds. "For parents who want to quit help can be provided." Raymond Niaura, PhD, the study's leader and senior author, is an adjunct professor of oncology at Georgetown Lombardi, and associate director for science of the Schroeder Institute for Tobacco Research and Policy Studies in Washington.

"This is one of the most comprehensive analyses of smoking risk in adolescents as it relates to family life," he says. "The findings that exposure to parental nicotine dependence is a critical factor influencing intergenerational transmission of smoking are striking and troubling - but they give us a direction to go in reducing that risk."

The study is a continuation of research Niaura began as a professor at Brown University, where he co-led the New England Family Study (NEFS).

More than 400 parents and their participating adolescent children ages 12-17 (second and third generations of NEFS participants), were interviewed at the beginning of the study with the children interviewed two more times, one year and then five years later.

The study shows that the more years a child was exposed to a parent's nicotine dependent smoking (using American Psychiatric Association criteria) the greater the risk that an adolescent would begin smoking or experimenting with cigarettes.

"We believe social learning plays an important role in intergenerational smoking," Mays says. "If social learning is key, then children can also learn from a parent who smokes that it is possible - and wise - to quit."