To gauge attention and memory, the team administered a well-known and highly used cognitive performance test before the cannabis use assignments went into effect, and then once a week for four weeks. After analyzing these results, the researchers found that marijuana abstainers showed a significant improvement on the verbal learning and recall sections of the test compared to baseline, and they continued to score higher throughout the month. Continued users did not improve. Moreover, abstainers had better overall memory scores than users at weeks one, two, and three. Neither cannabis use or abstinence were associated with a change in attention scores.
"The ability to learn or 'map down' new information, which is a critical facet of success in the classroom, improved with sustained non-use of cannabis," Schuster said. "Young cannabis users who stop regular – weekly or more – use may be better equipped to learn efficiently and therefore better positioned for academic success. We can confidently say that these findings strongly suggest that abstaining from cannabis helps young people learn, while continuing cannabis use may interfere with the learning process."
According to an MGH press release, two follow-up trials have already been initiated. One will compare the cognitive ability of cannabis abstainers, aged 13 to 19, to peers who have never used the drug. The other will follow young people who quit marijuana products for a longer time period.