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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.
The National Institute on Drug Abuse is a component of the National Institutes of Health, U.S. Department of Health and Human Services. NIDA supports more than 85 percent of the world's research on the health aspects of drug abuse and addiction. The Institute carries out a large variety of programs to ensure the rapid dissemination of research information and its implementation in policy and practice. Fact sheets on the health effects of drugs of abuse and other topics can be ordered free of charge in English and Spanish by calling NIDA Infofax at 1-888-NIH-NIDA (644-6432) or 1-888-TTY-NIDA (889-6432) for the deaf. These fact sheets and further information on NIDA research and other activities can be found on the NIDA home page at http://www.drugabuse.gov.