Children exposed to tobacco smoke in the home are up to three times more likely to have attention deficit hyperactive disorder (ADHD) compared to children from smoke free homes according to a new study from Spain.
Researchers also found that the association was stronger for kids with one ore more hours of secondhand smoke exposure every day. The results also held even after the researchers took into account a parents mental health and other factors that could lead to ADHD.
"We showed a significant and substantial dose-response association between (secondhand smoke) exposure in the home and a higher frequency of global mental problems," the authors write in Tobacco Control, online March 25.
Alicia Padron of the University of Miami Miller School of Medicine in Florida along with colleagues in Spain analyzed data from the 2011 to 2012 Spanish National Health Interview Survey. In the survey, parents of 2,357 children ranging from age 4 to 12 reported the amount of time their children were exposed to secondhand smoke every day. The parents also filled out questionnaires designed to evaluate the mental health of their children.
According to the results, about 8 percent of kids had a probably mental disorder. Seven percent of the kids were exposed to secondhand smoke for less than one hour per day while 4.5 percent were exposed for an hour or more each day.
After factoring in the mental health of the parents, family structure and socioeconomic background, children who were exposed to secondhand smoke for less than one hour per day were 50 percent more likely to have some type of mental disorder compared to children not exposed at all. Children who were exposed to secondhand smoke for more than one hour a day were close to three times more likely to suffer from a mental disorder.
More specifically, children exposed for less than one hour per day were twice as likely to have ADHD while kids exposed for more than hour a day were three times more likely to have ADHD.
"The association between secondhand smoke and global mental problems was mostly due to the impact of secondhand smoke on the attention-deficit and hyperactivity disorder," the authors write.
The team of researchers cautioned, however, that this study looks at a single point in time and cannot prove that secondhand smoke causes mental problems.
Frank Bandiera, a researcher with the University of Texas Health Science Center in Houston was not involved the study but liked that the researchers "controlled for parents' mental health in the new study because that could be a confounder."
"We're not sure if it's causal or not," Bandiera says. "I think (the research) is still in the early stages and the findings are inconclusive."
"We need to sort it out more, so we're not sure yet, but just as a precaution, I don't think parents should smoke at home - they should keep their kids away from secondhand smoke."
