A study from 2013, conducted by researchers from Melbourne to Barcelona, figured that different genes affect the influence of cannabis on the brain, and while performing all those cognitive tests on smokers vs. non-tokers, they also found that “daily cannabis use is not associated with executive function deficits.”
The study took 86 weed smokers and 58 non-drug users, genotyped them, then put them through a battery of different cognitive tests: sustained attention, working memory, monitoring/shifting, planning and decision making.
Researchers assumed from the beginning that cannabis use would negatively affect executive function, but their findings proved otherwise.
“We did not find any significant correlation between self-report lifetime estimates of cannabis use and performance in executive tests,” the study concludes.
Interestingly, the study also concluded, “daily cannabis consumption does not significantly impair executive functions among young users, not even in users with age of onset before 15 years old.”
Executive function, also known as cognitive control, basically describes your ability to function on a day-to-day basis as a regular person. So, as most pot smokers suspected, there’s no big problem with smoking weed – it won’t stop anyone from being a functional member of society.
Nonetheless, the study did find some drawbacks to consuming cannabis. “The main adverse effect of cannabis use on cognitive function was restricted to the domains of learning and memory, whereas effects were not significant for attention/executive control domain,” the study concludes.
They also hair-tested the study participants and found “a mild dose-dependent effect of cannabis use on planning skills.”
When looking into genetic differences that influence cannabis’ affect on the brain, they analyzed two genes: COMT val158met and 5-HTTLPR, two genes commonly studied for their connection with personal traits and neuropsychiatric disorders.
The study found that val/val carriers who smoke cannabis had lower sustained attention than val/val carriers who didn’t smoke; val carriers that smoke committed more shifting errors (in the monitoring/shifting test) than met/met carriers who also smoke.
What’s interesting is that met/met carriers normally do worse than val/val carriers and that “the pattern of performance was reversed in cannabis users.” Twenty percent of people were val/val carriers, and 37% were met/met in another study with a sample size of 486 people.
As far as the 5-HTTLPR polymorphism, researchers found that SERT s/s genotype weed smokers make poorer decisions than non-smokers from the same genotype. The s/s genotype normally performs worse on the Iowa Gambling Task (the decision making test), and cannabis just exacerbates it.
5-HTTLPR is the gene that codes for the serotonin transporter (SERT), and cannabinoids have previously been implicated in affecting serotonin. Apparently, high doses of cannabinoid agonists (that is, synthetic cannabinoids hundreds of times more powerful than THC) can reduce platelet serotonin levels. According to the study, “there is also evidence that the proposed link between cannabis use and depression is only present in cannabis users carrying the s/s genotype.” Certain behavior is characteristic of s/s genotypes, and cannabis just amplifies it.
So when you hear a story about someone who gets too paranoid or a little extra silly after taking a dab, it probably isn’t their fault; genetic makeup influences how pot affects you. That aside, most daily smokers or dabbers will be completely normal people with no problem operating in normal society.