Drink only once you're 21: study

Researchers found that studies done since 2006-when a new debate over age-21 laws flared up-have continued to demonstrate that the mandates work.

The laws, studies show, are associated with lower rates of drunk-driving crashes among young people. And it seems they also curb other hazards of heavy drinking-including suicide, dating violence and unprotected sex.

"The evidence is clear that there would be consequences if we lowered the legal drinking age," lead researcher William DeJong, Ph.D., of Boston University School of Public Health, said.

The US legal-drinking age has had a winding history. In the early 1970s, 29 states lowered their legal drinking age to 18, 19 or 20. But after a rise in drunk-driving crashes among young people, many states began to reverse course. A change in federal law eventually pushed all states to adopt a minimum drinking age of 21 by 1988.

But in recent years, the benefits of the age-21 law have been challenged.

In 2006, a non-profit called Choose Responsibility started campaigning for a change in the federal law. Two years later, a group of more than 100 US university presidents and chancellors known as the Amethyst Initiative called for a re-evaluation of the legal drinking age-citing a "clandestine" culture of heavy drinking episodes among college students as one reason that the age-21 law is not working.

Those moves grabbed a lot of media attention, and public health experts responded by launching new studies into the impact of the drinking-age law.

Based on DeJong's review, that research supports what earlier work had shown: Since the legal drinking age was set at 21, young people have been drinking less and are less likely to get into drunk-driving crashes.

The findings are published in the Journal of Studies on Alcohol and Drugs.