Research Shows that Memory Function in Adolescents Improves After 30 Days of Cannabis Abstinence

Image of a marijuana plant

With the first recreational cannabis shops set to opening Massachusetts within the next few weeks, many are worried about the long-term effects of regular marijuana use.

Parents of teens and adolescents may have cause for extra concern, as previous research studies have shown that regular cannabis use can impair brain functions important for memory and learning.

However, a new Mass General research study shows that there is light at the end of the tunnel even for teens and adolescents who use cannabis regularly.

The team, led by Randi Schuster, PhD, published results showing that a one-month break from cannabis use led to improved performance on tests of memory and cognitive functions.
The study is one of the first to track changes in cognitive function over time with regard to quitting cannabis.

Details of the Study

Researchers randomized 88 participants (aged 16-25 years) who disclosed using cannabis at least once week into two groups: One that continued to use cannabis during the study period and one that agreed to abstain from use for 30 days.

Participants in both groups were regularly evaluated using thinking and memory assessments as well as frequent urine tests to assure sobriety and track cannabis biomarkers.

 The results showed that the ability to learn and recall new information improved among those who stopped cannabis use, and this improvement was noticeable as soon as the first week of abstinence.

None of the participants in the group that continued using cannabis showed similar improvement.

“Our findings provide two pieces of convincing evidence. The first is that adolescents learn better when they are not using cannabis.

The second–which is the good news part of the story–is that at least some of the deficits associated with cannabis use are not permanent and actually pretty quickly after cannabis use stops.

Randi Schuster, PhD

What’s Next

In the future, researchers hope to continue studying the effects of cannabis on the young brain by including younger participants and evaluating the effects of abstinence for different lengths of time.

For now, while it may be best for adolescents to abstain from cannabis use altogether, it’s encouraging to know that it’s possible for some of these negative side effects to be reversed.

Watch a video summarizing the study’s findings:

About the Mass General Research Institute
Massachusetts General Hospital is home to the largest hospital-based research program in the United States. Our researchers work side-by-side with physicians to develop innovative new ways to diagnose, treat and prevent disease.
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