Research study · Frontiers in Psychiatry · 2026
How adolescent cannabis use reshapes the developing brain - a systematic review
Verified on PubMed Systematic review or meta-analysis
A 2026 systematic review in Frontiers in Psychiatry tested cannabis in cannabis use. The answer is that the findings point toward risk, but they do not prove that cannabis causes these problems. This review reinforces that adolescent cannabis use carries significant risks for brain development and addiction, but it does not provide definitive proof of.
In plain language
Study overview
This review gathered 36 studies that followed young people who used cannabis, mostly teenagers, and looked at their brains, thinking, and later life. The studies came from many countries and mostly watched people over time rather than testing a treatment.
Findings
The answer is that the findings point toward risk, but they do not prove that cannabis causes these problems. Teens who started using early showed differences in brain scans, were more likely to develop problems with the drug, and had more trouble later in school, work, and mental health, though other factors may explain much of this.
The deeper readScientific analysis
Background and hypothesis: Cannabis use initiation during adolescence has increased globally, raising concerns about neurodevelopmental consequences during this critical period when the brain undergoes extensive remodeling in cannabinoid receptor-rich regions. Study design: This systematic review examines neurodevelopmental consequences of adolescent cannabis use, focusing on structural brain changes, cognitive impacts, addiction vulnerability, and long-term outcomes. We searched PubMed, EMBASE, PsycINFO, and Web of Science (2000-2025) for studies examining cannabis effects in adolescent populations. Following PRISMA guidelines, two reviewers screened 3,421 records and assessed 156 full-text articles, including studies with neuroimaging, cognitive assessments, or longitudinal follow-up. Study results: Thirty-six studies involving 8,432 participants met criteria: 23 longitudinal cohorts (62.2%), 8 cross-sectional (22.2%), 4 RCTs (11.1%), and 1 case-control study (2.8%). Neuroimaging revealed dose-dependent alterations including reduced prefrontal cortical and hippocampal/amygdala volumes, accelerated cortical thinning in longitudinal studies, and impaired white matter connectivity correlating with initiation age. Cognitive findings were mixed. Epidemiological studies consistently showed elevated addiction risk (ORs 3.9 – 7.2) in adolescents versus adults. Long-term associations included educational difficulties, mental health problems, and functional impairment, though causal relationships remained unclear. Conclusions: Adolescent cannabis use associates with structural brain changes, elevated addiction risk, and variable cognitive effects, suggesting greater vulnerability versus adult-onset use. However, methodological limitations including confounders, heterogeneous definitions, and observational designs limit causal inference. Findings support age-specific prevention and specialized interventions while highlighting needs for rigorous longitudinal research establishing causality.
The paper
Citation
Ricci V, Sarni A, De Berardis D, Martinotti G, Maina G How adolescent cannabis use reshapes the developing brain — a systematic review. Frontiers in Psychiatry (2026). PubMed 42125461 · DOI
Limitations the authors noted
Heterogeneity in study designs, cannabis use definitions, age-of-onset cutoffs, and outcome measures precluded formal meta-analysis. Predominantly observational designs limit causal inference and risk residual confounding. Retrospective self-report subject to recall bias; biochemical verification only confirmed recent use. No standardized potency measures; contemporary high-THC products may differ from products used in older cohorts. Follow-up periods varied widely (6 months to 25 years). Publication bias not fully excluded; unpublished grey literature was included under moderate-to-high quality criteria. Several included studies had small samples (e.g., n=31-33) and limited power.
In practice
Why this matters
This review reinforces that adolescent cannabis use carries significant risks for brain development and addiction, but it does not provide definitive proof of causation to alter clinical practice beyond reinforcing existing caution.
Browse related research
Condition: Cannabis use Condition: Substance use Topic: adolescent cannabis use
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Reviewed by Dr. Caplan on October 15, 2026.
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