Cannabis users had worse verbal memory but adolescents were not more vulnerable than adults
The CannTeen study found that cannabis users had worse verbal episodic memory than non-users, but contrary to expectations, adolescent users (16-17) were not more cognitively impaired than adult users (26-29).
Quick Facts
What This Study Found
Cannabis users had significantly worse verbal episodic memory than controls (p=0.007). However, no significant differences were found between users and controls on spatial working memory or response inhibition, supported by Bayesian analyses. Critically, no interaction between age group and user status was found for any cognitive measure.
Key Numbers
274 total participants. Users: 4 days/week, 2.5 days since last use. Verbal memory: F(1,268)=7.423, p=0.007. No significant user-control differences on spatial working memory or response inhibition. No age-by-user interaction for any measure.
How They Did This
Cross-sectional study from the CannTeen project: 76 adolescent cannabis users (16-17), 63 adolescent controls, 71 adult users (26-29), and 64 adult controls. Users matched on cannabis frequency (4 days/week) and time since last use (2.5 days). Tested verbal memory, spatial working memory, and response inhibition.
Why This Research Matters
The adolescent brain is considered more vulnerable to cannabis, but this well-matched study did not find evidence for heightened adolescent vulnerability, challenging a widely held assumption.
The Bigger Picture
If adolescents are not uniquely vulnerable to cannabis-related cognitive effects compared to adults, the policy rationale for age-differentiated cannabis regulations may need to be reconsidered, or at least qualified.
What This Study Doesn't Tell Us
Cross-sectional design. Cannot determine if cognitive differences preceded cannabis use. Relatively small groups. Matching on frequency and recency of use may mask other exposure differences. Young adult age range (26-29) may still reflect ongoing neurodevelopment.
Questions This Raises
- ?Would longer-term follow-up reveal adolescent-specific vulnerabilities?
- ?Are there cognitive domains not tested that show age-specific effects?
Trust & Context
- Key Stat:
- Worse verbal memory in users, but no heightened adolescent vulnerability
- Evidence Grade:
- Well-designed cross-sectional study with matched groups and Bayesian analysis supporting null findings, but cannot establish causation.
- Study Age:
- Published in 2022.
- Original Title:
- The CannTeen study: verbal episodic memory, spatial working memory, and response inhibition in adolescent and adult cannabis users and age-matched controls.
- Published In:
- Psychopharmacology, 239(5), 1629-1641 (2022)
- Authors:
- Lawn, W, Fernandez-Vinson, N, Mokrysz, C(2), Hogg, G, Lees, R, Trinci, K, Petrilli, K, Borissova, A, Ofori, S, Waters, S, Michór, P, Wall, M B, Freeman, T P, Curran, H V
- Database ID:
- RTHC-03990
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Does cannabis affect memory?
Yes. Cannabis users had significantly worse verbal episodic memory (story recall) than non-users. However, spatial working memory and response inhibition were not affected.
Is cannabis worse for teen brains than adult brains?
This study did not find evidence for that. Adolescent cannabis users (16-17) were not more cognitively impaired than adult users (26-29) on any measure tested, despite both groups being matched on usage patterns.
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Cite This Study
https://rethinkthc.com/research/RTHC-03990APA
Lawn, W; Fernandez-Vinson, N; Mokrysz, C; Hogg, G; Lees, R; Trinci, K; Petrilli, K; Borissova, A; Ofori, S; Waters, S; Michór, P; Wall, M B; Freeman, T P; Curran, H V. (2022). The CannTeen study: verbal episodic memory, spatial working memory, and response inhibition in adolescent and adult cannabis users and age-matched controls.. Psychopharmacology, 239(5), 1629-1641. https://doi.org/10.1007/s00213-022-06143-3
MLA
Lawn, W, et al. "The CannTeen study: verbal episodic memory, spatial working memory, and response inhibition in adolescent and adult cannabis users and age-matched controls.." Psychopharmacology, 2022. https://doi.org/10.1007/s00213-022-06143-3
RethinkTHC
RethinkTHC Research Database. "The CannTeen study: verbal episodic memory, spatial working ..." RTHC-03990. Retrieved from https://rethinkthc.com/research/lawn-2022-the-cannteen-study-verbal
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.