WEDNESDAY, March 27 (HealthDay News) -- Ever wonder why some teens who try cigarettes get hooked quickly and others don't? The answer may lie in their genes, according to a new study that spans nearly four decades.
Researchers used data from earlier studies to construct a genetic risk score for heavy smokers. Next, they screened the genes of about 1,000 New Zealanders from birth to age 38 to see whether those with high risk scores got hooked on cigarettes more quickly as teens and whether they had a harder time kicking the habit as adults.
Teens with a high-risk genetic profile who tried smoking were 24 percent more likely to become daily smokers by age 15 and 43 percent more likely to smoke a pack a day by the time they were 18, the study showed.
These high-risk participants were also 27 percent more apt to become hooked on nicotine and 22 percent more likely to fail their quit-smoking attempts as adults, when compared to people with lower scores. Participants with high-risk gene scores had smoked about 7,300 more cigarettes than the average smoker by age 38, the study showed.
The findings appear online March 27 in JAMA Psychiatry.
A person's genetic risk profile did not predict whether they would try cigarettes. About 70 percent of study participants had tried smoking. Those who did try cigarettes and had a high-risk gene score were more likely to become heavy smokers. The risk score was a greater predictor of becoming a smoker than family history, the study showed.
"These genes accelerate the progression of smoking behaviors among adolescents," said study author Daniel Belsky, a postdoctoral research fellow at Duke University's Center for the Study of Aging and Human Development. "Most participants had tried smoking cigarettes when they were around 15, but most did not go on to become heavy smokers," he said.
There was no relationship between these genes and risk of becoming a heavy smoker when people took up smoking as adults. The crucial window appears to be in the teen years, said Belsky, also with the Duke University Institute for Genome Sciences & Policy.
"Adolescent manifestations of genetic risks are critical. If we can intervene and prevent teens from becoming smokers, we may be able to protect them for their whole lives," he said.
Antismoking campaigns that target youth are on the right track, he said. The next step is to find out how these genes influence smoking risk, and see if new quit-smoking drugs that interfere with the process can be developed.
Another expert talked about adolescents and smoking risk.
"These gene factors are critical for the rapid progression of smoking among teens," said Dr. Len Horovitz, a pulmonary specialist at Lenox Hill Hospital, in New York City.
"It's clear that there is a window of time where we can intervene and stop the progression of a teen becoming a heavy smoker," Horovitz said. "The previous thinking was that people who couldn't quit had just been smoking for too long." Instead, "it is a predestined, predetermined genetic factor that turns many teen smokers into lifelong heavy smokers."
Want to quit smoking, but don't know how? Visit the U.S. Centers for Disease Control and Prevention.
SOURCES: Len Horovitz, M.D., pulmonary specialist, Lenox Hill Hospital, New York City; Daniel W. Belsky, Ph.D., postdoctoral research fellow, Center for the Study of Aging and Human Development and Duke University Institute for Genome Sciences & Policy, Duke University, Durham, N.C.; March 27, 2013, JAMA Psychiatry, online
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