"Teenagers who smoke a pack of cigarettes or more a day are at markedly increased risk for three different kinds of anxiety disorders: panic disorder, agoraphobia and generalized anxiety disorder during early adulthood," says the study's lead author, Jeffrey G. Johnson, PhD, of Columbia University and New York State Psychiatric Institute.

Scientists have long known that smoking and anxiety are linked, but had not been certain if anxious teens were more likely to smoke, or if nicotine or other aspects of cigarette smoking increases anxiety among teens.

To learn more, Johnson and his colleagues interviewed 688 teenagers in 1985 and 1986, when they were an average age of 16, and interviewed them again six years later at an average age of 22. At each interview, detailed information was collected about anxiety symptoms and smoking habits.

The results show a strong link between smoking in teen years and later anxiety disorders. "Our findings indicate very clearly that adolescents who smoke a pack of cigarettes a day or more were 12 times more likely than others to have panic attacks, five times as likely to have agoraphobia and five times as likely to have generalized anxiety disorder during early adulthood," Johnson notes.

However, those experiencing anxiety disorders during adolescence were no more likely to start smoking than those who didn't have such attacks. The findings point to cigarettes as a cause, not an effect, of increased risk for anxiety disorders in early adulthood, Johnson says.

The study also notes that the consequences of some of these anxiety disorders can be very serious and can affect physical as well as mental well-being. "A lot of young people may only be aware of the long-term health consequences of smoking such as emphysema and lung cancer, but these findings show that these severe anxiety disorders can develop in a relatively short period of time, just a few years," Johnson adds.

A tobacco control expert with the American Cancer Society (ACS) says this research provides important new information. "Some scientists have thought that anxiety symptoms during adolescence were associated with the risk of initiation of smoking but what this new research suggests is the reverse, that smoking may actually contribute to the anxiety, rather than the anxiety being present and then leading to smoking behavior," says Ron Todd, MSEd, director of tobacco control for the ACS.

More research will be needed, says Todd, to confirm these new findings and seek more details about the link between teen smoking and anxiety disorders in early adulthood. But in the meantime, both Todd and Johnson agree, it is information that should be passed on to teens.

"This is one more piece of information we can share with young people about why they shouldn't start smoking," Todd says. "It outlines more potential health consequences of smoking, and may help us to persuade young people to stop smoking cigarettes, or not to start smoking."

More than 80 percent of adult smokers began smoking when they were 18 or younger, according to the Centers for Disease Control and Prevention (CDC). The ACS estimates that between 80 and 90 percent of all lung cancers, and lesser proportions of other cancers, are caused by smoking.