The research team found that drinking before the age of 15 increased a child's risk of becoming a heavy drinker.
The study of the relationship between age at first drink (AFD) and the risk of developing alcohol-use disorders (AUDs) during adulthood has found that the risk is greatest when AFD occurs before the age of 15.
"Some early drinkers become alcohol dependent while still in their teens, a time when those who have not yet started drinking are not even at risk of becoming dependent. By looking at adult-onset dependence, we can see for the first time that the association between early AFD and increased AUD risk ... is not time limited, but rather persists into adulthood," explained Deborah A. Dawson, staff scientist at the National Institute on Alcohol Abuse and Alcoholism (NIAAA) and corresponding author for the study.
"In addition, this study controls for a variety of individual risk factors that could contribute to both early drinking behavior and later alcohol problems," said Howard B. Moss, associate director for Clinical and Translational Research at NIAAA.
For the study, the researchers collected data from a three-year longitudinal study of U.S. drinkers 18 years of age and older at baseline (n=22,316).
They examined associations between three groups of AFD - younger than 15, between 15 and 17, and 18 years of age or older - and first incidence of alcohol dependence, abuse, and specific AUD criteria as defined by the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition. They also controlled for duration of exposure, family history and a wide range of baseline and childhood risk factors.
"The key finding of this study was that people who started drinking before age 15, and to a lesser extent those who started drinking at ages 15 to 17, were more likely to become alcohol dependent as adults than people who waited until 18 or older to start drinking. Past studies have often suggested that this association might result from common risk factors predisposing people to both early drinking and AUDs. Although the current study does not provide conclusive evidence that early drinking directly increases AUD risk, it suggests that it is premature to rule out the possibility of such a direct effect," said Dawson.
"By controlling for a variety of confounding risk factors in their analysis, Dawson and colleagues were able to demonstrate that ... early alcohol consumption itself, as a misguided choice or decision, is driving the relationship between early drinking and risk for development of later alcohol problems," observed Moss.
"We believe that impaired executive cognitive function (EGF) may lead to choices that favor the immediate pleasures of heavy drinking over avoiding the long-term risks of developing an AUD. Impaired EGF would likely result from frequent and/or extremely heavy drinking at early ages, not from the simple fact of having initiated drinking at early ages. The big question is whether the impaired EGF preceded and led to the early drinking (and the increased risk of AUD), or whether the early drinking caused the impaired EGF," said Dawson.
According to her, these findings would help in building a body of research that will eventually help scientists deduce whether early drinking is a marker of high risk for AUD or a direct risk factor for AUD.
"If the latter is true, it adds to the importance of preventing early drinking. Especially in light of the finding that the likelihood of developing these AUDs in adulthood is about 50 percent higher for persons who start drinking before 15 as for those who did not drink until 18 or older," she said.
The results of the study will be published in the December issue of Alcoholism: Clinical and Experimental Research and are currently available at Early View.