A new study from Northwestern University shows that frequent cannabis use during adolescence can affect memory in adulthood.
Notice to heavy cannabis smokers. A team of researchers from Northwestern University (Chicago) publishes today in the scientific journal Hippocampus a study that may well worry those who regularly use this drug.
Indeed, the results presented there suggest that frequent cannabis consumption during adolescence then affects memorization abilities in adulthood. And this is not the first such study they are conducting. Last April, British researchers highlighted the harmful effects of this drug on short-term memory.
Seahorse and “brain mapping”
The experiment carried out by the team is simple. 97 subjects were enrolled, including people who started smoking cannabis very regularly, at the age of 16 or 17, over a period of three years. At the time of the study, subjects must have stopped smoking for two years.
The study also focused on “control” subjects who had never smoked, as well as people with schizophrenia, some of whom had used cannabis regularly or not. A protocol which therefore made it possible to evaluate the effects of the drug on the memory of healthy people, but also those suffering from mental disorders.
First, the researchers looked at the morphology of the brain, in order to see the impact of cannabis on neuronal structures. Using brain mapping tools, they discovered abnormalities in former heavy smokers, particularly in the hippocampus.
This small area of the brain, located in the temporal lobe, is one of the centers of memory. The more regular and long the consumption of cannabis had been, the more the alterations of the hippocampus were important.
Long-term memory affected
Scientists sought to assess the impact of these structural changes on the memorization abilities of individuals. They had to listen to a story for a minute and restore as many elements as possible, half an hour later.
The results are final. Former regular smokers scored up to 18% lower than non-smokers. The more the consumption had been important and sustained over time, the worse the results.
In smokers with schizophrenia, performance was up to 26% lower than in schizophrenics who did not use marijuana. This suggests that the use of cannabis by these patients has a particularly negative impact on their cognitive capacities.
Become aware of the risks
These results are particularly alarming according to the authors of the study, because these long-term memory losses can affect the social life of individuals. Cannabis is the most widely used drug in the United States today, especially among young adults. More than 10% of the American population smokes cannabis at least once every year, and while not all of them end up consuming it regularly, scientists believe the damage to the brain is too great to ignore.
These researchers are also speaking out against the movement to decriminalize the use of cannabis, which extends to many American states, “for fear that this will explode the consumption of young people.”
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