Some think of a stoner as someone who is capable of little except whose cognitive ability is impaired, appears sleepy and is constantly looking for the next "high". If you don't, it's not surprising. As more and more countries legalize marijuana, the stereotypical mind-numbing effects of cannabis have become obsolete, often replaced by the drug's acceptance as an acceptable way to socialize, relax and sleep better. But what does it do to your cognitive ability?
But while society may have forgotten about the impact marijuana can have on the brain, science has not. Studies have long shown that getting high can impair cognitive function. Now, a new review of research, published Thursday in the journal Addiction, shows that the impact can last much longer than the initial high, especially for adolescents and young people.
“Our study has enabled us to highlight several areas of cognition affected by cannabis use, including concentration problems and difficulties with remembering and learning, which can have a significant impact on users' daily lives,” said co-author Dr. . Alexandre Dumais, associate professor of psychiatry at the University of Montreal.
“Cannabis use among young people can therefore lead to lower educational attainment and, in adults, poor job performance and dangerous driving behaviour. These effects can be worse in regular and heavy users.”
The impact of marijuana on the brain could be particularly damaging to the cognitive development of young people, whose brains are still developing, said Dr. Megan Moreno – a professor of pediatrics at the University of Wisconsin School of Medicine and Public Health.
“This study provides strong evidence for negative cognitive effects of cannabis use and should be considered critical evidence to prioritize cannabis use prevention in young people, also given that we now know that the brain continues to develop until age 25. Parents should are aware that adolescents who use cannabis are at risk of damage to their most important organ, their brain,” she continues.
Think of your cognitive ability, on a higher level
The newly published review looked at studies in more than 43.000 people and found a negative effect of tetrahydrocannabinol or THC, the main psychoactive compound in cannabis, at the higher thinking levels of the brain. Those executive functions include the ability to make decisions, remember important data, plan, organize, and solve problems, as well as controlling emotions and behavior.
Can you fix or reverse those deficits? Scientists don't know for sure.
“Research has shown that THC is a fat-soluble compound that can be stored in body fat and thus gradually released into the bloodstream over months,” Dumais said, adding that high-quality research is needed to establish the long-term effects of that exposure.
Some studies say that the negative effects on the brain may diminish after weed is stopped, but that may also depend on the amount, frequency, and years of marijuana use. The age at which cannabis use started can also play a role, if it falls within the crucial developmental period of the youthful brain.
“To date, the most consistent changes caused by cannabis use, mostly its chronic use, during childhood have been observed in the prefrontal cortex,” Dumais said. “Such changes could potentially lead to long-term disruption of cognitive and executive functions.”
In addition, some studies have shown that “early and frequent cannabis use in adolescence predicts poor cognition in adulthood”, he added.
While science is figuring this out, “preventive and interventional measures should be considered to educate young people about cannabis use and discourage them from using the substance in a chronic way as young people remain particularly susceptible to the effects of cannabis,” added Dumais.