WEDNESDAY, Nov. 29, 2006 (HealthDay News) -- Smoking may prime the adolescent brain to be more vulnerable to alcoholism and other addictions, a new study suggests.
"The younger they start smoking, the more their brains appear to be more susceptible to other addictions," said study co-author Richard Grucza, an epidemiologist at the Washington University School of Medicine in St. Louis. "So, the longer we can delay these behaviors, the better."
The findings are published in the December issue of Alcoholism: Clinical & Experimental Research.
"Everybody knows that smokers, especially in adolescence, have a higher likelihood of alcohol problems and dependence," Grucza said. "We wanted to see if that was solely attributable to the fact that they drink more than nonsmokers do or if the story was more complicated."
Grucza and a colleague reviewed survey data on the smoking and drinking practices of nearly 75,000 subjects aged 12-20, collected from 2002-2004 by the U.S. National Surveys on Drug Use and Health.
Compared to adolescent nonsmokers who drink alcohol, they found that adolescent smokers have more than a 50 percent higher risk of an alcohol-use disorder -- anything from alcohol abuse and dependence to alcohol-related trouble with the law.
The researchers also found that the smokers' risk of an alcohol-related disorder is elevated even when they drink the same amount of alcohol as nonsmokers, and that the risk is especially high among younger smokers and lighter drinkers. Among 15- to 17-year-olds who drank fewer than eight drinks a month, the prevalence of an alcohol problem was 20 percent in smokers, compared to only 5 percent in nonsmokers.
"This study provides additional important evidence that both smoking and drinking behaviors among U.S. youth are serious epidemics and also pediatric diseases -- ones increasingly understood as having origins and roots in early life behaviors and conditions," said Dr. Elissa Weitzman, of the Harvard School of Public Health, who was not part of the study. "Smoking and drinking present a troubling nexus of interacting risks. Use of one is a good indication that use and abuse of the other may be present, too," she said.
Weitzman said her own research has shown that youths who became regular smokers by age 15 were at a fivefold higher risk of developing an alcohol-related disorder by ages 18-21, compared to their nonsmoking peers who drink alcohol.
"The evidence is accumulating that early and youthful smoking and drinking are signposts of serious health problems and not -- as many continue to contend -- rites of passage typical of youthful exploration," she said.
"Youth, their parents and family members, health-care providers, teachers and counselors all would do well to take seriously the strong indication for other substance use from observation of use of just one of these substances," Weitzman said. "This may be especially the case for tobacco, where youthful smoking provides a stunning indicator of risk for problem levels of drinking in adolescence and young adulthood."
Grucza cautioned that his study documents only an association between adolescent smoking and problem drinking. "We're going to look further to see if it's a true cause-and-effect relationship," he said. "Even if it's not, then seeing who smokes can help us identify who's at risk for alcoholism and other addictions."
His findings mirror those of researchers who have studied animal models of addiction. "There are fairly striking parallels in the animal literature, which show that nicotine exposure during the animal equivalent of adolescence affects the brain's central-reward circuitry that is involved in all addictions," he said. "The adolescent brain is still very much in development. Unlike most people who start smoking in adulthood, adolescents who start smoking quickly become dependent on nicotine."
The health consequences are severe, Grucza added, because smoking and alcohol -- either separately or together -- account for more than 20 percent of deaths each year in the United States.
Although rates of adolescent smoking and drinking have declined since the 1970s, they've flattened out during the past decade and remain at alarmingly high levels, Grucza said.
"When people talk about 'gateway' drugs, they often focus on illegal drugs such as marijuana," Grucza said. "But the biggest public health problems are smoking and alcohol, with smoking being the single most important preventable cause of death."
"We need to look earlier in the 'gateway' series and see how smoking affects that process," Grucza said.
To learn more about the consequences of alcohol abuse, visit the U.S. National Institute on Alcohol Abuse and Alcoholism.