A new study exploring smoking, heavy drinking and marijuana use across three generations indicates that the children of a parent who uses any of these substances are more likely to smoke, binge drink or use marijuana in adolescence and adulthood. Drug transmission across generations, the study found, was for a general tendency to use these substances rather than to use any one specifically, with the exception of tobacco.
The children of cigarette smokers face an especially murky future, according to the University of Washington study published in the current issue of the Journal of Abnormal Child Psychology.
"If your parents were smokers it is a double whammy because you are more likely to use drugs in general and even more likely to smoke cigarettes," said Karl Hill, a research associate professor at the UW's Social Development Research Group and co-author of the new study. "There is something about tobacco that if parents smoke, their kids are more likely to smoke. It may be that parents who smoke might leave cigarettes around where their children can see and get to them. Parents may not leave marijuana and alcohol around in the same way."
Data from the paper were drawn from two long-term UW studies, the Seattle Social Development Project and the Intergenerational Project, which are tracing youth development and social and antisocial behavior. Participants were recruited from Seattle elementary schools, and 808 students have been followed since 1985. In addition to the participants, who make up generation 2, data were collected from their parents (generation 1) and their children (generation 3).
The researchers also found a transmission link between the three generations - child behavior problems such as conduct disorder (getting into fights, stealing) attention deficit disorder (lack of focus, can't sit still or maintain attention) and oppositional defiant disorder (problems with authority).
"Children of smokers, heavy drinkers or marijuana users are more likely to have behavior problems when they are young, and consequently more likely to have drug problems themselves as they get old," said Jennifer Bailey, lead author of the study and a UW research scientist. "These children then grow up to be adult substance users, whose kids have behavior problems and the cycle is repeated."
The researchers found that the link between general substance use and childhood behavior problems held up even when they controlled for such variable social factors as marital status, education and neighborhood conditions.
However, they noted the popular notion that the children of substance users are fated to grow up using drugs is wrong.
"Many people think that drug-using parents will have drug-using kids, but the effect is only modest and far from being deterministic," said Bailey. "A lot of children whose parents are smokers, heavy drinkers or marijuana users do not go on to be drug users or drinkers."
Bailey and Hill believe their findings have strong practical applications in breaking the intergenerational cycles of drug use. "This means we don't have to tailor intervention programs for individual drugs except tobacco. These findings suggest that a general substance abuse educational program with an emphasis on tobacco should be effective," said Hill.
Bailey added that prevention programs for chronic and severe child conduct problems also need to be continued and may aid in interrupting the intergenerational transmission of substance use.
The benefits of successful interventions "may echo across generation" the researchers wrote, noting the negative effects of substance use by grandparents are observed not only in their children but also in their grandchildren.
The National Institute on Drug Abuse funded the research. Co-authors of the paper were Sabrina Oesterle, a research assistant professor at the Social Development Research Group, and J. David Hawkins, former director of the research groups and a professor of social work.