Both academic studies and casual observation support the view that smokers tend to drink, and drinkers tend to smoke. New research using nationally representative data from the U.S. finds that smokers - particularly adolescent smokers - clearly have a greater vulnerability to alcohol-use disorders (AUDs) than do non-smokers.

Results are published in the December issue of Alcoholism: Clinical & Experimental Research.

“Smoking and alcohol – separately, or together – account for more than 20 percent of deaths in the United States,” said Richard A. Grucza, an epidemiologist at Washington University School of Medicine and corresponding author for the study. “Cigarettes and alcohol are also known to be ‘gateway’ drugs, that is, the overwhelming majority of illegal drug users begin their use with one or both of these legal drugs.”

“We have known about the link between cigarette smoking and alcohol use for a while, but we have not really asked the question, as the authors here asked, whether use of one could increase the vulnerability of becoming addicted to the other,” said Kevin W Chen, associate professor at the University of Maryland School of Medicine.

• Popular and clinical lore support the strong connection between smoking and alcohol consumption.
• Adolescent smokers appear to have a greater vulnerability to developing alcohol-use disorders.
• Results indicate that smoking “primes” the brain for subsequent addiction to alcohol and possibly other drugs.

“Ours was the first,” added Grucza, “to examine quantity of drinking in relationship to smoking and AUDs. Our central questions were: Can this association be explained by the fact that smokers are heavier drinkers, or is there something else going on? In other words, do smokers appear to be more sensitive to the effects of alcohol?” The short answer appears to be yes.

Researchers examined data from an aggregate of 2002 through 2004 U.S. National Surveys on Drug Use and Health. Randomly selected, household-dwelling adolescents and young adults (n=74,836) were selected from the non-institutionalized and civilian American population and queried about their drinking and smoking practices.

Results indicate that smokers – particularly adolescent smokers –have a greater vulnerability to AUDs than do non-smokers.

“In general, smokers were at more than a 50 percent higher risk, although the differences were larger in younger adolescents and among light drinkers,” said Grucza. “For example, among 15- to 17-year-olds who drank fewer than eight drinks in the month before the survey, more than 20 percent reported an AUD, compared with about five percent among the non-smoking group with the same level of drinking. We conclude that, although smokers do drink higher rates of alcohol, this alone does not explain their higher vulnerability to AUDs.”

Grucza said that these findings go beyond the popular view that bad behaviors like smoking and drinking to excess simply tend to “go together,” especially during adolescence. “It seems that smoking makes the adolescent brain more vulnerable to other addictions,” he said. “Addictive drugs all act on a part of the brain that is described as the ‘central reward circuitry.’” Once this system is exposed to one drug, the brain may become more sensitive to the effects of other drugs, as demonstrated by a number of rodent studies.

“Studies like this will set up an alert – for those who consider adolescent smoking tolerable – to rethink the issue, or perceive the problem differently,” noted Chen. “Although we do not know the exact causal relation between the two, the damage to our health is so severe that we need to create a more objective image to reject both smoking and drinking among adolescents.”

“Ours is the first study to ... establish a correlation between adolescent smoking and AUDs that cannot be explained by heavier drinking,” said Grucza. “Now we, and hopefully others, need to investigate whether or not smoking actually causes adolescents to be more susceptible to AUDs. Our results are in line with an emerging literature that shows adolescence may be a unique window of vulnerability for addictions development. If it is proven that nicotine directly impacts vulnerability to alcoholism and other addictions, then that is a new, strong message to add to the health-education arsenal. However, even if this correlation is completely non-causal, these results can help to identify kids who are at risk for AUDs.”