People who use both alcohol and marijuana are more likely to speed, text, intentionally run red lights, and drive aggressively than those who don’t, according to new data.

The American Automobile Association (AAA) Foundation’s annual Traffic Safety Culture Index found that drivers who use both marijuana and alcohol were also significantly more prone to driving under the influence of alcohol compared to those who only drink alcohol but do not use marijuana.

“These data show the alarming impact of alcohol and marijuana use on the choices drivers make when they get behind the wheel,” said Jake Nelson, AAA’s director of traffic safety advocacy and research.

The report found that compared to alcohol-only users, drivers who admitted to using both were more likely to report such behaviors as:

  • Speeding on residential streets (55%) vs. alcohol-only (35%)
  • Aggressive driving (52%) vs. alcohol-only (28%)
  • Intentional red-light running (48%) vs alcohol-only (32%)
  • Texting while driving (40%) vs. alcohol-only (21%)

The research was published in Transportation Research Record.