Teens and young adults that frequently use cannabis suffer poor memory, mood, attention, and a drop in IQ, according to a recent study from the American Psychology Association.
Krista Lisdahl, director of the brain imaging and neuropsychology lab at University of Wisconsin-Milwaukee, explained how the study was conducted.
“We would compare a group of regular cannabis users to non-users. We would match groups on age, gender, ethnicity, and reading ability–measures quality of education,” Lisdahl said.“If groups are different on anything else we would statistically control for them, such as alcohol use, nicotine use, body mass index, and depressive symptoms.”
According to Health Canada, in 2011 39.4 per cent of Canadians have used cannabis at some point in their lifetime. The average age of initiation was 15.6 years old.
“The findings across these studies have shown that cannabis use in adolescents and young adults is associated with poorer processing speed, sustained attention, cognitive control, and verbal memory,” Lisdahl said. “We also see lower GPAs, increased problems at school, increased sleep problems, and poorer self-reported mood.”
“Further, we see that the more joints people smoke and the younger they were when they started, the worse they look,” Lisdahl said.
According to Health Canada, cannabis should not be used by any person under the age of 18, or in any patient who has a history of hypersensitivity to any cannabinoid or to smoke. The adverse effects of cannabis use on mental health are greater during development, particularly during adolescence, than in adulthood.
Lisdahl said the person’s age and the strain of cannabis used affect how and which neurological side effect occurs.
“In adults, it looks like low levels of use–I would define as less than three uses per month–are not associated with significant changes in cognition or brain structure,” Lisdahl said.
“For adult chronic users–weekly to daily–cannabinoids can stay in the body and brain for weeks,” Lisdahl said. “Regular use in adults is associated with poorer memory and processing speed, and although these effects are not as great as what we see in teens.”
Lisdahl said that she only had data for teens who used cannabis fewer than five times per year.
“Those teens do not show long-lasting changes in the brain, but using even a few times a month is associated with accumulation of the drug and we would not recommend teens ever use with any consistency,” Lisdahl said.
“I hope that young people make choices for themselves. The brain is still maturing until the mid 20s, some regions up until 30,” said Lisdahl. “If you value your intelligence, cognitive processing, sleep quality, and emotional health—do not use cannabis in your teens and as a young adult keep your use to less than once a month.”
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