“Cannabis narrows your field of vision, as does alcohol. Your peripheral vision is decreased, and your reaction times are decreased,” says Rand Teed, a Regina addictions counsellor and drug and alcohol educator.
But Teed says cannabis also has its own effects, so it’s “bad in a different way.”
“Alcohol tends to make us more reckless and aggressive. Cannabis tends to work in an opposite way so we’re more laid back and less reactive — which, if you’re driving, isn’t really something you want either. You want somebody who is paying attention and can multi-task well. Cannabis reduces the capacity to multi-task,” Teed explains.
He says it’s a misconceptions that cannabis helps a person concentrate when they’re driving.
“People will say ‘Well, I can really focus when I’m driving high.’ And you might be able to focus on one thing, but you can’t pay attention to six things. When you’re driving you need to pay attention to everything else that’s going on.”
Teed says both cannabis and alcohol make it difficult for a person to figure out if they’re actually capable of driving.
“The problem that a lot of people don’t understand is that both cannabis and alcohol impair pre-frontal cortex function. One of the things that your pre-frontal cortex is supposed to be doing is self-assessing. So the thing that we’re using to tell ourselves that we’re OK isn’t actually working. You’ve lost capacity to accurately self assess,” says Teed.
He says combining cannabis and alcohol can cause even bigger problems.
“They have a synergistic effect. Alcohol exaggerates the effects of cannabis, and cannabis exaggerates the effect of alcohol. So you will get drunker on less alcohol if it’s mixed with cannabis, and you’ll get more intoxicated from cannabis if it’s mixed with alcohol.”
So the usual crackdown on drunk drivers during the Christmas party season may be more complicated this year, now that cannabis is legal.
“Enforcement this Christmas season may be different as officers may have the new oral fluid devices to use if they suspect THC or cocaine to be impairing an individual’s ability to drive. If a person is swabbed and they are above the cutoff level for THC, a blood sample may be demanded. If that sample comes back containing the above-mentioned levels of THC they will be charged under the new section,” says Const. Jon Turner of the Regina Police Service.
He is one of 11 members of the Regina Police Service trained as drug recognition experts.
Turner says there are several characteristics of drivers impaired by cannabis, including: relaxed inhibitions, distorted perceptions of time and distance, short-term memory loss, drowsiness, loss of co-ordination and possibly dilated pupils.
THC (tetrahydrocannabinol) is responsible for how a person’s brain and body respond to cannabis.
“Cannabis does impair your ability to operate a vehicle safely. Even though you may not feel impaired, you may still have enough THC concentration in your blood to be over the legal limit. It is difficult to determine what that concentration is for several reasons: it’s different for each individual, it’s affected by the amount of cannabis consumed, how long ago it was consumed and the THC level,” explains Constable Turner.
And Rand Teed also has a warning about cannabis-laced snacks that might be part of holiday get-togethers.
“Onset time for impairment from edibles is much longer than onset time for impairment from smoking cannabis. If you smoke cannabis, it reaches its maximum effect in about ten minutes. With edibles it’s more like 45 minutes to an hour to reach maximum effect. So you might take an edible, and don’t feel anything and decide to drive home, than you might all of a sudden — while you’re driving — have an impairment onset that you didn’t expect.”
What’s it like to drive high? Perhaps something can be learned from history.
Almost 40 years ago, the danger of driving under the influence of marijuana was investigated by Car and Driver magazine. In an article in June 1980 entitled “Puff, the Dangerous Driver” Car and Driver had four staff writers try to navigate a driving course before and after smoking marijuana. They recorded faster times after smoking up — but also reported they had problems concentrating and were more easily distracted.
Patrick Bedard said, “The real problem is remembering what I’m doing. Taking notes is a struggle. I forget what I’ve been writing in midsentence … My mind wanders. If a pedestrian stepped out in front of me, I might not notice …. I can still drive. Just don’t ask how to spell my name.”
Rich Ceppos wrote, “Marijuana erodes driving skills in a far more subtle way than alcohol.”
Stephen Smith found that “smoking marijuana heightens all your perceptions. Trouble is, you don’t seem to process the information efficiently.”
Don Sherman concluded, “Dope may not hamper your driving ability, but it will kill your long-term concentration. And probably you too, if you’re foolish enough to dope and drive.”
And Rand Teed says back then, pot was far less potent than it is today.
“Marijuana in the 1980s was probably 15 per cent THC, and most of the stuff now is between 20 per cent and 30 per cent. And there’s a new family of cannabis products that are above 80 per cent. So today’s marijuana has a much stronger impairing factor.”
Dale Edward Johnson is a member of the Automobile Journalists Association of Canada.