Lowering the legal drinking age may be associated with an increased high school dropout rate, a new US study suggests.
The study looked back at high school dropout rates in the 1970s to mid-80s - a time when many US states lowered the age at which young people could legally buy alcohol.
Researchers found that when the minimum drinking age was lowered to 18, high school dropout rates rose by 4 to 13 per cent, depending on the data source.
Black and Hispanic students - who were already more vulnerable to dropping out - appeared more affected than white students, researchers said.
The findings do not prove that the 18 drinking age was to blame, according to lead researcher Andrew Plunk, an assistant professor of pediatrics at Eastern Virginia Medical School in US.
However, state drinking-age policies would likely be unrelated to the personal factors that put kids at risk of drinking problems or dropping out, he said.
States also made those policy changes based on US trends at the time - mainly, the belief that with the voting age lowered to 18, the legal drinking age should drop too, Plunk said.
So it is unlikely that other events happening within states would explain the connection to high school dropout rates.
"The minimum legal drinking age changes how easy it is for a young person to get alcohol," Plunk said.
"In places where it was lowered to 18, it's likely that more high school students were able to get alcohol from their friends," Plunk said.
For certain vulnerable kids, that access might lower their chances of finishing high school.
Policies that allowed 18-year-olds to buy alcohol showed a particular impact on minority students, as well as young people whose parents had drinking problems. In that latter group, the dropout rate rose by 40 per cent.
In the mid-1980s, US legislation returned the legal drinking age to 21 nationwide, researchers said.
However, there is an ongoing debate about lowering it again - largely as a way to combat clandestine binge drinking on college campuses, they said.
The argument is that college students who can legally buy alcohol at bars and restaurants will drink more responsibly.
"I think this study gives us some idea of what could happen if we lower the legal drinking age," Plunk said.
"It suggests to me that we'd see this same dropout phenomenon again," he said.
The study was published in the Journal of Studies on Alcohol and Drugs.
