Chances are the only thing you remember about your first swig of alcohol is how bad the stuff tasted. What you didn't know is the person who gave you that first drink and when you had it says a lot about your predisposition to imbibe later in life.

A national study by a University of Iowa-led team has found that adolescents who get their first drink from a friend are more likely to drink sooner in life, which past studies show makes them more prone to abusing alcohol when they get older. The finding is designed to help specialists predict when adolescents are likely to first consume alcohol, with the aim of heading off problem drinking at the pass.

"When you start drinking, even with kids who come from alcoholic families, they don't get their first drinks from their family," says Samuel Kuperman, a child and adolescent psychiatrist at the UI. "They get their first drinks from their friends. They have to be able to get it. If they have friends who have alcohol, then it's easier for them to have that first drink."

The basis for the study, published this month in the journal Pediatrics, is compelling: One-third of eighth graders in the United States report they've tried alcohol, according to a 2011 study of 20,000 teenagers conducted by the University of Michigan and funded by the National Institutes of Health. By 10th grade, more than half say they've had a first drink, and that percentage shoots to 70 percent by their senior year.

"There's something driving kids to drink," explains Kuperman, corresponding author on the paper. "Maybe it's the coolness factor or some mystique about it. So, we're trying to educate kids about the risks associated with drinking and give them alternatives."

Kuperman and his team built their formula from two longstanding measures of adolescent drinking behavior-the Semi-Structured Assessment for the Genetics and Alcoholism and the Achenbach Youth Self Report. From those measures of nearly two-dozen variables and a review of the literature, the UI-led team found five to be the most important predictors: two separate measures of disruptive behavior, a family history of alcohol dependence, a measure of poor social skills, and whether most best friends drink alcohol.

The researchers then looked at how the five variables worked in concert. Surprisingly, a best friend who drank and had access to alcohol was the most important predictor. In fact, adolescents whose best friend used alcohol were twice as likely to have a first drink, the researchers found. Moreover, if considered independently of the other variables, teenagers whose best friends drank are three times as likely to begin drinking themselves, the study found, underscoring the sway that friends have in adolescents' drinking behavior.

"Family history doesn't necessarily drive the age of first drink," notes Kuperman, who has studied teen drinking for more than a decade. "It's access. At that age (14 or 15), access trumps all. As they get older, then family history plays a larger role."

The current study drew from a pool of 820 adolescents at six sites across the country. The participants were 14 to 17 years old, with a median age of 15.5, nearly identical to the typical age of an adolescent's first drink found in previous studies. More than eight in 10 respondents came from what the researchers deemed high-risk families, but more than half of the teenagers had no alcohol-dependent parents. Tellingly, among those adolescents who reported having had drunk alcohol, nearly four in ten said their best friends also drank.

The result underscores previous findings that teenagers who have their first drink before 15 years of age are more likely to abuse alcohol or become dependent. It also supports the screening questions selected in the National Institute on Alcohol Abuse and Alcoholism and the American Academy of Pediatrics initiative to identify and help youth at risk for alcohol use, the researchers write.

Kuperman, whose faculty appointment is in the Carver College of Medicine, says he hopes to use the study to delve into the genetics underpinning alcoholism, chiefly tracking adolescents who use alcohol and see whether they have genes that match up with their parents if they also are problem drinkers.

"We're trying to separate out those who experiment with alcohol to those who go on to problematic drinking," he says.

Contributing authors include John Kramer from the UI; Grace Chan and Victor Hesselbrock, University of Connecticut Health Center; Leah Wetherill, Indiana University School of Medicine; Kathleen Bucholz, Washington University School of Medicine in St. Louis; Danielle Dick, Virginia Commonwealth University; Bernice Porjesz and Madhavi Rangaswamy, State University of New York Downstate Medical Center, Brooklyn; and Marc Schuckit (principal investigator on the grant), University of California San Diego School of Medicine.

The National Institutes of Health (grant number: 5 U10 AA008401), the National Institute on Alcohol Abuse and Alcoholism and the National Institute on Drug Abuse funded the study.