An analysis of the data from the National Household Survey on Drug Abuse interviews with 22,292 smokers showed that adolescents, women, and whites are particularly vulnerable to developing nicotine-dependence symptoms, according to the researchers who published their findings in the September issue of Nicotine and Tobacco Research.
Dr. Denise B. Kandel, of Columbia University and the New York State Psychiatric Institute, and her colleagues found that at similar or lower levels of use nicotine dependency rates are higher among females than males and higher among whites than minorities. They are lowest among older adults (over 50).
The researchers theorize that these differences in rates of dependency symptoms reflect differences in sensitivity to nicotine.
"This is the first study to analyze the varying responses to increased levels of cigarette smoking - varying by age, gender, and ethnicity - and the study suggests that the threshold for determining nicotine dependence may vary among different groups," said Dr. Alan I. Leshner, director, National Institute on Drug Abuse (NIDA). "This research is a first step in investigating nicotine dependence in various population groups."
The analysis is based on data collected during 1991-93 because the surveys from these years included the proper information to measure nicotine dependence.
Nicotine dependence was measured using six diagnostic criteria and symptoms: tolerance (needing ever-increasing amounts to feel the effects), withdrawal symptoms, using more nicotine than intended, failed efforts to cut down usage, negative social and job-related consequences, and persistent health problems.
Using these criteria, teenagers, women, and whites experience more dependence symptoms while using the same, or fewer, number of cigarettes than other groups - men, older people, and nonwhites. Dependence rates increase sharply as consumption increased, up to a half-pack of cigarettes a day. Dependent smokers are more likely to continue smoking and to use increasingly larger amounts to sustain the nicotine effect.
Adolescents, who smoke significantly fewer cigarettes a day than adults, experience substantially higher rates of dependence than do adults at the same level of usage. Researchers believe this is due to adolescents' higher sensitivity at low doses of nicotine, compared with adults.
Adolescents appear to be particularly vulnerable to becoming nicotine-dependent, especially at low levels of cigarette consumption, the study concluded.