One of the biggest risk factors for drinking and driving is having friends who condone the behavior, according to researchers from the University of Michigan Transportation Research Institute.

The Behavioral Health News Service reported March 20 that the belief that there are few negative consequences for drinking and driving also is a major risk factor. Unlike risk factors identified in past studies, these warning signs applied specifically to drunk driving, not just drinking in general.

"To policymakers I'd say, it's probably going to be worthwhile to try to change a person's network of friends, help them find friends who don't drink and drive, and avoid those who do," said lead study author Raymond Bingham, Ph.D. "It's probably harder than some interventions, but worth it."

Kenneth Beck, Ph.D., a transportation safety researcher, said tough law enforcement also could help by raising the perception of risk associated with drinking and driving.

Researchers interviewed about 3,500 young adults for the study.

The study appears in the April 2007 issue of the journal Alcoholism: Clinical and Experimental Research.