A new study claims to have found evidence that cannabis consumers could be more dangerous drivers whether they are under the influence or not.
Researchers from Harvard University and McLean Hospital asked 28 chronic, heavy cannabis consumers and 17 non-cannabis users to drive in a customized driving simulator. At the time of the driving test, the cannabis users had not used for at least 12 hours and were not under the influence of THC during the test based on urine samples.
“Heavy use was defined by daily or near daily use, a minimum of four or five times a week, with a lifetime exposure of 1,500 times,” said Staci Gruber, director of the Marijuana Investigations for Neuroscientific Discovery (MIND) program at McLean Hospital, the largest psychiatric teaching hospital of Harvard Medical School.
The study found drivers who consume cannabis on a regular basis are more likely to drive faster, run more red lights and get into more accidents than those who don’t smoke cannabis. Tests also found cannabis users were more likely to swerve into other lanes of traffic.
Researchers found the worst performing members of the study were those who began smoking cannabis regularly before age 16. The theory behind that thought is early cannabis use changes the brain and causes people to make more rash and impulsive decisions.
“It didn’t surprise us that performance differences on the driving simulator were primarily seen in the early onset group,” said co-author Mary Katherine Dahlger, a post-doctoral fellow Marijuana Investigations Harvard group. “Research has consistently shown that early substance use, including the use of cannabis, is associated with poorer cognitive performance.”