Number of Childhood Symptoms of ADHD Strongly Linked To Adult Risk of Smoking

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Childhood Symptoms of ADHD

The greater the number of reported symptoms of attention-deficit hyperactivity disorder (ADHD) shown in childhood, the greater the risk a person is of becoming a regular smoker, according to researchers at Duke University Medical Center.

The research team cautions that their findings do not mean that a diagnosis of ADHD as a child leads a person to become a smoker, and they emphasized that their study only looked at self-reported symptoms of ADHD and not at a clinical diagnosis. However, the findings make it all the more important that children who exhibit a high number of ADHD symptoms receive additional or specialized education about the hazards of smoking, they said.

ADHD is a common psychiatric disorder that affects approximately five percent of school aged children and is characterized by difficulty paying attention, hyperactivity and impulsivity. In order to meet the criteria for having ADHD, a person must exhibit a certain number of symptoms in multiple settings and be impaired as a result of these symptoms.

Their study results appear in the October 2005 issue of Archives of General Psychiatry. The research was funded by the National Institutes of Health and the department of psychiatry at Duke.

"We wanted to know why people with ADHD smoke more often than those who don't have ADHD," said Scott H. Kollins, Ph.D., assistant professor of psychiatry at Duke and lead author on the study. "It may be something about the symptoms themselves that cause people to smoke, but we aren't certain of that. What our data clearly show is that for every symptom of ADHD reported in childhood, the stronger the likelihood that person would smoke regularly during adolescence or early adulthood. This relationship held true even for individuals reporting fewer than the number of symptoms we see in people with a diagnosis of ADHD."

The research team sought to determine whether ADHD symptoms increased the lifetime risk for regular smoking, regardless of current smoking status. To determine the ADHD-smoking link, the team used a database of information gathered from thousands of young adults surveyed as part of the National Longitudinal Study of Adolescent Health, a nationally representative sample of adolescents. The researchers used data on 13,852 adolescents in the survey for whom complete survey data were available on ADHD symptoms and tobacco use. The survey participants were asked to rate their frequency of a range of ADHD symptoms of inattentiveness and impulsivity, as well as reporting their smoking status.

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"We have established a strong association between ADHD symptoms and smoking," Kollins said of the researchers' analysis of the data. "Specifically, we found a strong relationship between the age of onset of smoking and the number of reported symptoms of ADHD in childhood. Smokers who reported the most inattentive or hyperactive-impulsive symptoms as children started smoking, on average, a year earlier than those reporting the fewest numbers of symptoms. This extra year of smoking is very important from a public health perspective."

Among current smokers in the sample, more ADHD symptoms were also associated with higher consumption of cigarettes per day.

"The results were surprising because we learned that the smoking risks aren't necessarily related to having ADHD itself, but rather for each symptom of ADHD that you have, the greater your chances of becoming a smoker," said Joseph McClernon, Ph.D., assistant research professor of psychiatry at Duke and an author on the study. "We need to figure out why this relationship is there. We want to understand the mechanisms that underlie what we've found and see if that information can be used to prevent smoking or help more people quit."

Additional research is needed to more precisely determine the nature of the relationship between the symptoms of ADHD and smoking risk. The investigators said, for example, they would like to determine whether specific symptoms or clusters of symptoms are more strongly associated with the risk of becoming a regular smoker.

The team is already examining the differences between adult smokers with and without ADHD in smoking cessation programs. The researchers are particularly interested in learning whether those with ADHD have a harder time quitting and if their withdrawal symptoms are any worse.

"We think people with ADHD may benefit in some way from either more intensive cessation programs or modified programs that are more in tune with their needs, McClernon added. "They may require treatments we haven't imagined yet."

The researchers point out there may be problems with presenting smoking prevention programs to children with symptoms of ADHD. They are concerned that a certain percentage of young students who need the information the most aren't going to really "get it" because of their inability to pay close attention during presentations or classes.

"We may need to get more creative in how we think about talking to kids about smoking," added McClernon. "If your kids show signs of ADHD, it's probably a good idea to be even more proactive about talking with them about smoking and not starting in the first place." - DURHAM, N.C.

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