In a randomized trial of 238 adolescents, those who regularly used cannabis and were incentivized to abstain for four weeks showed improved inhibitory control compared to those who continued using, and performed similarly to non-users by week 4.
Adolescents who use cannabis, parents, school counselors, and clinicians working with teen substance use.
What the researchers found
At baseline, cannabis-using adolescents had worse verbal memory and processing speed than non-users. After four weeks of incentivized abstinence, abstinent cannabis users showed greater improvement in inhibitory control compared to monitoring controls (beta=-10.9, p=0.037) and performed similarly to the non-user group.
Why it matters
This is one of the first randomized trials showing that adolescent brains can recover cognitive function relatively quickly after stopping cannabis use. The four-week timeframe is practical and encouraging for both clinicians and young people considering a break from cannabis.
The numbers in context
238 adolescents (51% female, 55% White, 18% Black, 9% Asian). 154 cannabis users, 84 non-users. Inhibitory control improvement in abstinence group: beta=-10.9, p=0.037. Abstinent users similar to non-users at week 4. No significant group differences in memory or attention at week 4.
How the study worked
Randomized clinical trial with 238 Greater Boston adolescents (ages 13-19): 154 regular cannabis users randomized to incentivized abstinence or non-contingent monitoring, plus 84 non-users as reference. Weekly cognitive testing over four weeks assessed executive function, memory, and attention.
What this study cannot tell us
Contingency management (cash incentives) for abstinence may not reflect real-world motivation. Four weeks may not capture full recovery. No biological verification of complete abstinence. Practice effects from weekly testing could account for some improvement across all groups. Sample was from a single geographic area.
How to read the evidence
Randomized design with non-user reference group and weekly cognitive assessment, providing strong evidence for short-term cognitive recovery.
When this study was published
Published 2025.
The bigger picture
The adolescent brain is still developing, making it potentially more vulnerable to cannabis effects but also more capable of recovery. This study suggests that the cognitive costs of regular adolescent cannabis use are at least partially reversible, which is a more hopeful message than permanent damage narratives.
Questions still open
- Whether cognitive improvements continue to increase beyond four weeks of abstinence
- Whether heavier or longer-duration cannabis users take longer to recover cognitive function
Common questions
Does this mean cannabis permanently damages teen brains?
Why did memory not improve as much as inhibitory control?
Read the original research
Neurocognitive outcomes in adolescents with and without four weeks of cannabis abstinence: a randomized clinical trial using contingency management.
Frontiers in psychiatry, 16, 1723633
Citation
Schuster, Randi M; Costello, Meghan A; Potter, Kevin; Torquati, Matteo; Gilman, Jodi M; Evins, A Eden. (2025). Neurocognitive outcomes in adolescents with and without four weeks of cannabis abstinence: a randomized clinical trial using contingency management.. Frontiers in psychiatry, 16, 1723633. https://doi.org/10.3389/fpsyt.2025.1723633
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