Teens who have certain genetic risk factors associated with smoking are not more likely to try cigarettes, but when they do, they are more likely to smoke daily and heavily and to pick up the habit more quickly than those without such risk factors, according to analysis of data from a long-term study. The study, published online in JAMA Psychiatry today, also found that teens with genetic risk factors were more likely to fail at attempts to quit in adulthood.
One in 5 US adults smoke cigarettes daily, despite public campaigns warning about health risks and burdensome taxes on cigarette purchases. Most smokers attempt to quit at some point, but more than half fail. Understanding why smoking remains such a persistent and widespread public health problem has been the focus of much research, and a growing body of evidence suggests that genetic factors may help explain why some individuals become dependent on cigarettes and struggle to quit.
To better understand the effects of genes in smoking behavior, an international team of scientists examined the relationship between genetic risk factors for smoking and smoking behavior in a study that followed up more than 1000 people in New Zealand from birth to age 38 years. They found individuals who had genetic variations associated with smoking and those with a lower-risk genetic profile were equally likely to start smoking. But among those who tried smoking cigarettes, those with greater genetic risk factors associated with smoking were more likely than those at lower genetic risk to become smokers of 20 or more cigarettes a day and to do so more rapidly. Moreover, those individuals who started smoking but never became daily or heavy smokers had low genetic risk.
Of the 406 individuals who smoked daily during 14 years of follow-up, 90% attempted to quit at some point and 51% reported failing at such an attempt. Those at higher genetic risk were more likely to fail.
The findings suggest that genes associated with smoking risk may mediate individuals’ response to nicotine. However, the researchers said that the magnitude of these gene-associated effects on smoking were not large enough to warrant screening based on genetic risk. They noted that “children who our study would classify at high genetic risk are not guaranteed to become addicted if they try smoking, and, even more importantly, children we would classify at low genetic risk are not immune to addiction.”
The researchers said that their findings highlight the importance of efforts to prevent the initiation of smoking among youth.
“Public health policies that make it harder for teens to become regular smokers should continue to be a focus in antismoking efforts,” said lead author Daniel W. Belsky, PhD, of Duke University in Durham, North Carolina, in a statement.