A new study says that nicotine dependence has remained steady among adults, although the number of people taking up smoking has declined.
The research led by Columbia University Mailman School of Public Health researchers has shown that nicotine dependence has actually increased among some groups.
Previous studies have found that since the 1964 U.S. Surgeon General report, the number of people who smoke cigarettes has declined. The Mailman School of Public Health study takes this research a step further by distinguishing occasional smokers from heavy smokers.
"Regular, heavy cigarette use frequently characterizes nicotine dependence and is the pattern of use thought to be the most detrimental to health and longevity, but it has not been addressed in previous estimates of the decline in smoking prevalence," said Dr Renee Goodwin, associate professor of Epidemiology at the Mailman School of Public Health and principal investigator of the study.
"Rather, earlier research mainly addressed tobacco use or cigarette smoking per se rather than examining the frequency and duration of cigarette use in detail," she added.
The new study finds not only that the number of nicotine-addicted Americans has held steady over the past several decades, but also that the proportion of cigarette smokers who are addicted to nicotine nowadays is greater than in previous generations.
Dr. Goodwin suggests that fewer people are taking up smoking, perhaps because of anti-cigarette campaigns, leaving the ranks of current smokers filled with the nicotine dependent.
It is also thought that socioeconomic status is a factor in cigarette use. The current study finds that younger women living in poverty had the highest rates of nicotine dependence, compared with older generations, and those not living in poverty.
This suggests that despite increases in taxes and smoking costs, those most vulnerable are still heavily affected.
The study appears in American Journal of Public Health.