In plain language
Long-term heavy cannabis use is known to impair memory in adults, but adolescents may be especially vulnerable because their brains are still developing. This study asked whether teenagers who use cannabis — even for only a couple of years — already show measurable memory problems, and whether those problems are due to cannabis specifically rather than alcohol or other factors.
The researchers tested 181 Australian adolescents aged 16 to 20 (average age 18.3) using the Rey Auditory Verbal Learning Test, one of the most widely used measures of learning and memory. They compared 52 cannabis users (who had used for an average of just 2.4 years, about 14 days per month), 67 alcohol users, and 62 non-user controls. The groups were carefully matched on age, education, alcohol consumption, and — unusually for this field — on intellectual ability measured years earlier, before drug use began.
Cannabis users performed significantly worse than both alcohol users and non-users on every performance measure: they learned fewer words, forgot more after interference and delay, and retrieved less of what they had learned. The more cannabis they had used, and the younger they started, the worse their memory — while alcohol exposure showed no such relationship. Despite relatively brief exposure, these teens showed memory deficits similar to those reported in adult long-term heavy users, reinforcing concerns that cannabis harms the developing brain.
Key findings
- Adolescent cannabis users performed significantly worse than matched alcohol users and non-users on all verbal learning and memory indices, recalling fewer words overall (p < .001) with impaired learning (p < .001), retention (p < .001), and retrieval (p < .05); effect sizes ranged from Cohen’s d = 0.43 to 0.84.
- The degree of memory impairment increased with the duration, quantity, frequency, and earlier age of onset of cannabis use — a dose-response pattern.
- Earlier onset of regular cannabis use predicted worse memory even after controlling for total cannabis exposure, suggesting particular vulnerability of the younger developing brain.
- Impairment was unrelated to alcohol exposure or other drug use, and alcohol users did not differ from non-users, pointing to cannabis-specific effects.
- Deficits remained after controlling for premorbid intellectual ability (measured prospectively before use began), tobacco, ecstasy use, and anxiety and depressive symptoms, and there were no gender differences.
- Despite an average of only 2.4 years of cannabis use, the adolescent users showed memory deficits similar to those documented in adult long-term heavy cannabis users.
How to cite
APA
Solowij, N., Jones, K. A., Rozman, M. E., Davis, S. M., Ciarrochi, J., Heaven, P. C. L., Lubman, D. I., & Yücel, M. (2011). Verbal learning and memory in adolescent cannabis users, alcohol users and non-users. Psychopharmacology, 216(1), 131-144. https://doi.org/10.1007/s00213-011-2203-x
BibTeX
@article{solowij2011verbal,
author = {Solowij, Nadia and Jones, Katy A. and Rozman, Megan E. and Davis, Sasha M. and Ciarrochi, Joseph and Heaven, Patrick C. L. and Lubman, Dan I. and Y{\"u}cel, Murat},
title = {Verbal learning and memory in adolescent cannabis users, alcohol users and non-users},
journal = {Psychopharmacology},
year = {2011},
volume = {216},
number = {1},
pages = {131--144},
doi = {10.1007/s00213-011-2203-x}
}
Related work
- All publications by Joseph Ciarrochi (searchable, with free PDFs)
- Process-Based Therapy & Idionomic Analysis
Author: Joseph Ciarrochi (ORCID 0000-0003-0471-8100). Free copy hosted with permission for scholarly use. Please cite the published version via the DOI above.