Alcohol and Tobacco Use

Patterns of Co-Occurring Consumption and Dependence
by National Institute of Health

Epidemiologists have conducted nationwide surveys, such as the National Household Survey on Drug Abuse (NHSDA) and the National Comorbidity Survey (NCS), to estimate the prevalence of either the individual or the concurrent consumption of and dependence on alcohol and tobacco. These estimates indicated that for both alcohol and tobacco, use was already relatively high among the youngest respondents, peaked among young adults, and declined in older age groups. A similar pattern existed for concurrent alcohol and tobacco use. Moreover, these estimates showed only moderate gender differences. With respect to dependence, the age-related prevalence patterns differed somewhat for alcohol and tobacco, with the prevalence of tobacco dependence relatively lower among the youngest respondents compared with the prevalence of alcohol dependence. The age-related pattern for concurrent alcohol and tobacco dependence was similar to that found for tobacco dependence.

The concurrent use of alcohol and tobacco and its consequences can be analyzed at numerous levels. For example, basic research has explored the mechanisms through which alcohol and nicotine affect the body - particularly the brain - and lead to dependence. Such investigations have found that both drugs act on the brain through overlapping signaling pathways in which the brain chemical (neurotransmitter) dopamine plays a central role. Moreover, such studies have identified certain protein molecules located on various brain cells (nicotinic receptors) that interact with nicotine and which, at least indirectly, mediate the reinforcing functions of both alcohol and nicotine.

Other investigators have examined the breakdown (metabolism) of alcohol and nicotine, noting an overlap between the metabolic systems that dispose of both drugs in the body. Clinical studies have addressed the effects of both drugs on tissues and organs. Such analyses have found that concurrent alcohol and tobacco use significantly enhances the risk of certain cancers, particularly of the oral cavity and can adversely affect cardiovascular health.

Other areas of research aim to elucidate the reasons and mechanisms underlying both alcohol and tobacco use. For example, ethnographic studies have investigated the role of social customs or habits as determinants of concurrent alcohol and tobacco use. Behavioral analyses have focused on the initiation of alcohol and tobacco use that often occurs during adolescence, when youngpeople experiment with multiple adult social roles. According to these studies, adolescents typically begin using such alcoholic beverages as beer and wine, followed by either distilled spirits or cigarettes. Moreover, experimental evidence indicates that alcohol consumption promotes smoking and that smoking possibly promotes drinking. Finally, clinical research on twins has substantiated the idea that common genetic factors may underlie a predisposition to both alcohol and nicotine dependence, and additional research in both humans and animal models is exploring the interplay of environmental and genetic risk factors.

All of these biological and behavioral observations, which focus on the individual, strongly suggest that a causal relationship between alcohol and tobacco use also exists at the higher level of population analysis. Thus, alcohol use may influence tobacco use, not only in the individual but also within a community. To elucidate these population-level influences, however, researchers must determine the extent of alcohol use, tobacco use, and concurrent use of both drugs in the population. This article addresses these epidemiological issues using data obtained from two U.S. studies, the National Household Survey on Drug Abuse and the National Comorbidity Survey. The article also examines whether substantial variations in alcohol and tobacco use exist between population subgroups (different age groups and groups segregated by gender).

Survey Design

The NHSDA has been conducted annually since the late 1980s, whereas the NCS was conducted in 1990 to 1992. Both surveys are designed and conducted to allow researchers to recruit a representative and valid sample of respondents and to measure the frequency of illicit drug use and other sensitive behaviors. For example, in both surveys the respondents are asked to complete a private, confidential assessment, either marking their responses on an answer sheet that will be seen only by the respondent or providing their responses to an interviewer. Moreover, the statistical analyses conducted to yield the resulting estimates of certain behaviors take into account numerous aspects of the survey design and use appropriate estimation procedures. The strengths of these epidemiological survey methods also ensure an accurate assessment of the separate and concurrent use of two licit drugs, alcohol and tobacco.

The data presented in this article are based on the NHSDAs conducted from 1995 to 1997 and on the NCS conducted during a fieldwork interval from 1990 to 1992, the most recent years for which data were available for both surveys. In the corresponding figures, the NHSDA-based estimates are presented for each of the 3 survey years to provide a sense of the degree of consistency of these estimates.

For both the NHSDA and the NCS, the respondents were classified according to their ages as measured by their self-reports. The NHSDA survey included respondents age 12 and older, whereas the NCS included respondents ages 15 to 54. To provide more stable estimates of alcohol and tobacco use across various age groups, the statistical analyses of the NHSDA data included a "smoothing function," a statistical approach that produces a less variable pattern of findings across different age groups by "borrowing" information from adjacent age groups. To quantify the potential burden of alcohol and tobacco dependence in the U.S. population, some new analyses of NCS data have also been conducted.

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.