How adolescent cannabis use reshapes the developing brain — a systematic review
Valerio Ricci, Alessandro Sarni, Domenico de Berardis, Giovanni Martinotti, Giuseppe Maina
Frontiers in Psychiatry April 27, 2026 DOI: 10.3389/fpsyt.2026.1822300 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Systematic review Longitudinal Cross-sectional Peer reviewed |
|---|---|
| Sample size | 8,432 |
| Population | Adolescent cannabis users, drawn from 36 studies including longitudinal cohorts, cross-sectional studies, randomized controlled trials, and one case-control study |
| Topics | Cannabis |
| Key findings | Adolescent cannabis use is associated with structural brain changes, elevated addiction risk compared with adult-onset use (odds ratios 3.9-7.2), and variable cognitive effects, with some studies showing persistent deficits after prolonged abstinence and others finding no effects after controlling for confounders. The authors conclude that methodological limitations, including confounders, heterogeneous definitions, and observational designs, limit causal inference, and they support age-specific prevention and specialized interventions while calling for rigorous longitudinal research. |
Abstract
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 — some showed persistent deficits after prolonged abstinence in adolescent-onset users, others found no effects after controlling for confounders. 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. Systematic review registration https://www.crd.york.ac.uk/prospero/, identifierCRD420251165329.
Comparable studies
Other systematic reviews and meta-analyses on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Effects of cannabis use on outcomes of psychotic disorders: systematic review People with psychotic disorders, as examined in 13 longitudinal studies | 2008 | Systematic review | |
| The Impact of Cannabis Use on Cognitive Functioning in Patients With Schizophrenia: A Meta-analysis of Existing Findings and New Data in a First-Episode Sample Patients with established schizophrenia (meta-analysis: 572) and patients with... | 2010 | Meta-analysis and cross-sectional observational study | n = 700 |
| Medicinal cannabis for psychiatric disorders: a clinically-focused systematic review | 2020 | Systematic review | |
| Neuroimaging in cannabis use: a systematic review of the literature Cannabis users and controls in neuroimaging studies | 2009 | Systematic review | |
| Human Laboratory Studies on Cannabinoids and Psychosis. Healthy human subjects and individuals with schizophrenia | 2016 | Systematic review |
Citations in the library
Cited by 2
Cites 12
- Association between cannabis use and symptom dimensions in schizophrenia spectrum disorders: an individual participant data meta-analysis on 3053 individuals EClinicalMedicine September 8, 2023
- Cannabis and suicide risk in first-episode psychosis: Mechanisms, interactions, and intervention strategies. Asian Journal of Psychiatry July 10, 2025
- First episode psychosis with and without the use of cannabis and synthetic cannabinoids: Psychopathology, global functioning and suicidal ideation and antipsychotic effectiveness. Psychiatry Research 2023
- Cannabis use disorder and dissociation: A report from a prospective first-episode psychosis study. Drug and Alcohol Dependence October 1, 2021
- Resting state functional connectivity in the default mode network: Relationships between cannabis use, gender, and cognition in adolescents and young adults NeuroImage: Clinical April 8, 2021
and 7 more in the library