(Reuters Health) - Adolescents may be cautious while they’re learning to drive, but a new study suggests they get downright dangerous once their license allows them to hit the road without a grownup in the car.

Teen drivers have long been synonymous with risky maneuvers on the road and plenty of previous research has also found novice drivers have higher crash rates than people with more experience. The current study helps pinpoint when teen driving may be riskiest by using cameras and sensors inside cars to examine driving habits for parents and children over almost two years, starting when teens got their learner’s permits.

While teens only had permits, their chance of being in a crash or nearly missing a collision as well as their odds of exhibiting risky driving behavior like speeding, swerving, and slamming the brakes were similar to the adults, the study found.

In the first year after teens had their licenses, however, they were more than six times more likely to crash or narrowly escape collisions than the adults, and they were also almost four times more likely to exhibit risky driving behaviors.

“Parents are in the vehicle during the learner phase and this makes all the difference,” said lead study author Pnina Gershon, a researcher at the Eunice Kennedy Shriver National Institute of Child Health and Human Development at the National Institutes of Health in Bethesda, Maryland.

Among other things, parents can help teen drivers stay focused on the road, offer tips on how to drive safely, and help these new drivers avoid dangerous situations, Gershon said by email.

“Even during independent driving, when parents are passengers and presumably are not in the teaching role, teens drive more safely than when they drive alone,” Gershon added. “But on their own, without a parent or adult present, we find that teens’ risky driving behaviors, crash and near crash rates increase dramatically.”

Adolescent drivers have disproportionately higher crash rates than other driver age groups, accounting for six percent of licensed drivers in the U.S. but nine percent of fatal crashes, researchers note in the Journal of Adolescent Health.

The current study included 49 girls and 41 boys who were about 16 years old on average.

During the study, teens drove an average of 5,445 miles and a total of about 490,000 miles. Their parents, meanwhile, drove more than twice as many miles.

As a group, teens had a total of 148 near crashes, 69 collisions, and 9 crashes that were reported to the police. This translated into an average of 2.4 incidents per driver.

By contrast, parents had a total of 84 close calls, 28 collisions, and 2 crashes that were reported to the police. This translated into an average of 1.2 incidents per driver.

Teens also had a total of 18,378 incidents of risky driving, which translated into roughly 108 events per driver. The parents, meanwhile, had 5,272 incidents of risky driving, or about 59 per driver.

For young drivers, the highest rates of crashes, near misses and risky driving occurred in the months immediately after they got licenses and started hitting the road without a parent in the car.

Beyond its small size, the study also wasn’t a controlled experiment designed to prove whether or how parents’ presence in the car might directly improve teen driving safety. Researchers also didn’t follow teens long enough to see how their driving records might change with a few more years of experience.

Even so, the results underscore the importance of parents modeling the behavior they want their teens to have behind the wheel, said Despina Stavrinos, an injury prevention researcher at the University of Alabama at Birmingham who wasn’t involved in the study.

If parents drive recklessly, speed, text while on the road, or fail to buckle up, teens will probably follow suit, Stavrinos said by email.

“Kids are watching and learning and developing their own ideas about what is acceptable driving behavior,” Stavrinos added. “They might be thinking - if mom or dad does it, then it must be safe for me to do it.”

SOURCE: bit.ly/2uV6BSv Journal of Adolescent Health, online July 10, 2018.