Neuropsychological effects of cannabis use by continent and age: a systematic review
Lidia Venero-hidalgo, Francisca Carvajal, Fernando Rodrı́guez de Fonseca, Víctor José Villanueva-blasco
Frontiers in Psychology May 28, 2026 Peer reviewed DOI: 10.3389/fpsyg.2026.1728743 via OpenAlex
Summary
Cannabis use during adolescence and young adulthood is linked to memory problems, especially in episodic and working memory, but effects on executive functions are less consistent and depend on age, how much cannabis is used, and the type of cognitive test. Studies from the Americas, many of which followed participants over time, more often found negative associations between cannabis use and cognitive performance. European studies showed mixed results, possibly due to differences in cannabis products, patterns of co-use, and measurement methods. Evidence from Asia was limited. Overall, cognitive differences are more reliably seen in adolescents than in young adults, shaped by developmental, methodological, and contextual factors.
Study at a glance
| Design | systematic review |
|---|---|
| Sample size | 22 |
| Population | adolescents and young adults who use cannabis |
| Key finding | Memory-related impairments, particularly in episodic and working memory, were the most consistent cognitive findings, while evidence for executive function deficits was more heterogeneous and varied by age, exposure, study design, and cognitive task. |
Abstract
Introduction: Cannabis use during adolescence and young adulthood has been associated with neurocognitive alterations. However, limited attention has been paid to whether these findings vary according to developmental stage and regional context. This systematic review examined the neurocognitive effects of cannabis use in adolescents and young adults, with particular attention to age-related patterns and geographic variation. Methods: Following PRISMA guidelines, a systematic search was conducted in PubMed/MEDLINE, Scopus, Web of Science, and OpenGrey for studies published between 1 January 2019 and 30 June 2024. Eligible studies assessed cognitive performance in adolescent or young adult cannabis users. Methodological quality was appraised using the Mixed Methods Appraisal Tool, and certainty in the body of evidence was evaluated using the Grading of Recommendations Assessment, Development and Evaluation approach. Results: Twenty-two studies met the inclusion criteria. Across the included studies, memory-related impairments were the most consistent findings, particularly in episodic and working memory. Evidence regarding executive functions was more heterogeneous and appeared to vary according to age group, exposure profile, study design, and cognitive task. Studies from the Americas, many of them longitudinal, more often reported negative associations between cannabis use and cognitive performance. European findings were more mixed, possibly reflecting differences in product characteristics, co-use patterns, and measurement approaches. Evidence from Asia was limited. Discussion: Overall, the findings suggest that cannabis-related neurocognitive differences are more consistently detected in adolescent samples than in young-adult samples, although this pattern is likely shaped by developmental, methodological, and contextual factors. Future research should improve comparability in exposure definitions, control of confounding variables, and selection of cognitive measures.