WEDNESDAY, Dec. 24, 2014 (HealthDay News) -- Teens are more likely to start smoking or drinking with each additional symptom they have of attention-deficit hyperactivity disorder (ADHD) or conduct disorder, new research suggests.
"Our findings underscore the need to counsel families about the risk of substance use as [these] children approach adolescence," said study author Dr. William Brinkman, research director at Cincinnati Pediatric Research Group, which is part of Cincinnati Children's Hospital. "This need is heightened among children with ADHD and/or conduct disorder diagnoses or symptoms."
Brinkman's team analyzed data on more than 2,500 teens, aged 12 to 15, in a national survey conducted with their parents between 2000 and 2004.
First, the researchers identified the teens with an ADHD and/or conduct disorder diagnosis, as well as those with the symptoms of either disorder, regardless of whether there was a diagnosis. Conduct disorder is characterized by aggressive, destructive or deceitful behavior. Children with ADHD tend to be hyperactive, impulsive and/or inattentive.
Then Brinkman's team compared use of tobacco and alcohol among the teens, to look for a link between symptoms of ADHD or conduct disorder and substance use.
Brinkman said that 45 percent of the children in the study had at least one ADHD symptom, and nearly 15 percent had at least one conduct disorder symptom.
For each additional ADHD symptom related to inattention -- but not hyperactivity or impulsivity -- the risk that a teen would use tobacco or alcohol increased by 8 percent to 10 percent. Similarly, each additional conduct disorder symptom was linked to a 31 percent increase in the likelihood of using tobacco, according to the study.
A very small percentage of teens in the study -- about 1.5 percent -- were diagnosed with both ADHD and conduct disorder. These teens were more than three times more likely to use tobacco or alcohol, even after accounting for differences in age, race/ethnicity, sex, household income and having a household member who smoked.
The findings were published recently in the journal Drug and Alcohol Dependence.
Brinkman said more research may provide clues as to why the link exists between these disorders and substance use.
"Because nicotine can improve attention and arousal, some have speculated that the association between inattention symptoms and higher rates of tobacco use suggests a form of self-medication for ADHD," Brinkman said. "Certainly higher rates of risk taking and novelty seeking has been documented among children with a diagnosis of ADHD, as well as those with ADHD symptoms [but too few for a diagnosis]."
Social pressures may be involved as well, suggested Dr. Glen Elliott, chief psychiatrist and medical director of Children's Health Council in Palo Alto, Calif.
"It is important to emphasize that not all teens with ADHD follow this path, just a higher percentage than those without ADHD," Elliott said. "We believe it is a combination of impulsive decision-making and perhaps the social strain that ADHD can place on the individual, who may feel unable to connect with peers in socially acceptable ways and therefore more vulnerable to trying other methods such as doing things peers dare them to do or that they view as 'cool' or 'adult.' "
Elliott said the study provides new insights into the interplay between ADHD and conduct disorder. But it sheds little light on whether treating ADHD, either earlier in childhood or during adolescence, might change the risk of starting to smoke or drink, he said.
"We believe medication can make a difference, but the evidence is not nearly as compelling as we wish it were -- partly because teens often go through a phase of refusing to take medications just when it might do them the most good," Elliott said. "Just as with parents of any teenager, there is no guaranteed way to prevent a son or daughter from experimenting if they are determined to do so."
The best tools parents have, Elliott said, are setting consistent and clear expectations for their children, closely monitoring them, praising them for good choices and administering appropriate, meaningful consequences for poor choices -- while also showing children early on what behavior is acceptable.
"Adolescence is hard," Elliott said. "And having ADHD can make it harder. So parents need to be vigilant, caring, consistent and involved."
Visit the U.S. National Institute of Mental Health for more on ADHD.