Researchers from the University of Montreal, Canada, have found that cannabis affects the working memory of girls at high school age more than their male counterparts. The researchers warn that this may hinder both their academic success and their memory in adulthood.
Conducted across 31 high schools in the Greater Montreal area, the researchers administered surveys and neuropsychological tests to assess the memory and cognitive performance of over 3,826 students in relation to their use of cannabis and alcohol. Collecting data every year for five years, they were able to follow a cohort of students from start to finish of their high school careers.
In the end, the surveys demonstrated a gradual increase in alcohol and cannabis use from Grades 1 to 5 in both boys and girls. While alcohol consumption was not associated with significant cognitive and mnemonic decline, cannabis use portrayed another story. Although the researchers found a decrease in performance among boys and girls during tests, they found especially significant differences in spatial working memory among girls who started using the substance at the beginning of high school.
"Working memory, which involves the ability to process and store information over a short period of time, is related to the prefrontal cortex," says Patricia Conrod, lead author of the study. "This is the last region of the brain to develop in adolescents, but this development occurs earlier in girls than in boys."
"Several studies have shown that early marijuana use affects the maturation of the prefrontal cortex, and our results corroborate them: girls who report using cannabis in early adolescence show a deficit in working memory by the end of high school compared to girls who used later."
The researchers also note that, according to Statistics Canada's 2018 data, students who smoke cannabis are 2.3 times more likely to drop out of high school than those who do not. Although the reasons behind this are not fully known, given the seemingly damaging effects cannabis has on developing brains, the researchers say more must be done to prevent early use of the plant.