Everyone knows that driving vehicles under the influence of alcohol is dangerous, and drinking and driving is considered a very serious offense in the country. The depressant effects of the substance have already been well established, and there is no lack of studies on the subject.
The same thing does not happen, however, with marijuana, at least not to the same extent. Despite being an affordable and widely used drug — according to the 3rd National Survey on Drug Use by the Brazilian Population, coordinated by Fiocruz, 7.7% of Brazilians aged 12 to 65 have used the drug at least once in their lives, which makes it the most used illicit drug in Brazil — there is little data on the use of the substance in the country.
In places where use is decriminalized, such as Portugal, part of the US, Canada, Uruguay and the Netherlands, among others, it is easier to obtain data on consumption.
In April of this year, a reader sent an email to the health section of the American newspaper New York Times to see if driving a vehicle under the influence of marijuana was as dangerous as driving under the influence of alcohol. Columnist Dani Blum has provided some interesting data that allow us to analyze the effects of the drug.
A randomized study carried out in the USA with 191 regular users of marijuana made it possible to evaluate the effects of drug use on driving a motor vehicle. Participants were instructed to smoke as much as they wanted for 10 minutes, with a minimum of four puffs. After 30 minutes, and throughout the day, they went through a series of simulated driving tests.
Before each simulation, the researchers asked the participants how “high” they considered themselves to be and whether they thought they were fit to drive.
After half an hour of consumption, only half of the participants said they felt safe to drive the vehicle, but after 90 minutes, about 70% considered themselves good to drive, although this group did worse in the tests than the placebo group.
The researchers then considered that although users felt more capable of driving after 1:30 am, they were still not up to the task, confirming what other studies have already shown: marijuana can compromise the ability to discern between what is or not safe.
In addition, the study also showed that many users took about 4h30 to be able to drive like a person who has not consumed the drug. The researchers caution, however, that more studies are needed to determine individual biological differences and drug delivery methods in driving performance.
Another study, carried out in France in 2011 with 4,000 people, analyzed drivers involved in fatal accidents and compared the findings with those of another study, conducted between 2001 and 2003. The researchers concluded that the risk of a drunk person being responsible for an accident with fatal victims is 17.8 times higher than that of a person who did not drink.
Among those who smoked marijuana, the same risk is 1.65 times greater than that of those who did not use the drug. Much less likely than alcohol, but still considerable, to cause a serious accident.
It is not easy to carry out studies involving the use of marijuana because, to be more precise, they would need to analyze the tolerance to use, dose, route of administration and concentration of THC (the main active component of marijuana) of the drug used, in addition to other individual characteristics. important in assessing the effects of consumption.
In addition, studies have already shown that THC, because it is very lipophilic, infiltrates and persists in areas of the body with a high fat content, such as adipose tissues and the brain.
This means that marijuana, especially in those who use it chronically, accumulates in the tissues and can be released and detected in tests even days after consumption. Thus, it is more difficult to determine whether a driver involved in an accident, for example, was under the influence of the drug at the time of the accident or if he had used the drug days before.
With alcohol, the opposite occurs: the body eliminates the drug more quickly, making intoxication easier to detect. Furthermore, it is easy to determine the dose of the substance.
Marijuana, in addition to being able to compromise judgment at times that require quick decision-making, can also alter perception of time and reflexes, although users are not always aware of this. The last effect is common to psychotropic drugs, a group of chemical substances that act on the central nervous system and include anxiolytics (“soothing”), antidepressants, anticonvulsants, and also illicit substances such as marijuana, alcohol and cocaine.
“All psychotropics, although they have different classes, in general can interfere with the ability to drive, mainly because they cause changes in reflexes and also in wakefulness, as some can cause drowsiness, such as benzodiazepines and marijuana”, explains Dr. José Gallucci Neto, psychiatrist at the HCFMUSP Psychiatric Institute.
Therefore, despite being less dangerous for driving than alcohol, you should avoid consuming marijuana and other psychotropic substances, licit or illicit, that alter reflexes or cause drowsiness before driving.