A systematic review of 16 prospective studies found that earlier age of first cannabis use specifically predicted cannabis use disorder but not problems with other substances like alcohol.
Prevention program designers, adolescent health providers, substance use researchers, parents
What the researchers found
Across 16 prospective studies, earlier age of cannabis use onset was consistently associated with later cannabis use disorder (CUD) and cannabis-related negative consequences. However, the evidence for earlier onset predicting other substance use problems (like alcohol) was mixed. Cannabis use frequency accounted for much of the risk for negative consequences, but the association with CUD remained independent of frequency, suggesting early onset carries unique risk beyond simply using more.
Why it matters
This review provides specificity to the "gateway drug" concern: early cannabis use predicts cannabis-specific problems rather than broader substance use escalation. This shapes prevention messaging and targets delay of onset as a specific protective strategy.
The numbers in context
16 prospective studies included; early onset consistently predicted CUD and cannabis consequences; mixed findings for other substance problems; frequency mediated consequences but not CUD risk; only 1 study had low risk of bias
How the study worked
Systematic review of prospective studies published 2000-2024 examining age of cannabis onset and later substance use problems. Searched PsycINFO, Web of Science, and PubMed. Required prospective design, adolescent onset, and control for key risk factors. Risk of bias assessed with ROBINS-I. PROSPERO-registered.
What this study cannot tell us
Only one study had low risk of bias; eight had high or very high risk. Heterogeneity in how "age of onset" was measured across studies. Could not conduct meta-analysis due to study variability. Most studies did not adequately control for all confounders.
How to read the evidence
Moderate: systematic review of prospective studies with PROSPERO registration, but limited by high risk of bias in most included studies.
When this study was published
2025 publication reviewing studies through December 2024
The bigger picture
Prevention programs that succeed in delaying cannabis use onset may specifically reduce CUD rates even if they do not affect other substance use patterns. This supports targeted rather than blanket prevention approaches.
Questions still open
- What is the threshold age below which onset becomes particularly risky for CUD?
- Is the CUD-specific risk mediated by neurobiological vulnerability in adolescence?
Read the original research
Age of onset of cannabis use and substance use problems: A systematic review of prospective studies.
Addictive behaviors, 163, 108259
Citation
Hamaoui, Jad; Pocuca, Nina; Ditoma, Mikaela; Héguy, Camille; Simard, Cléa; Aubin, Raphael; Lucic, Anastasia; Castellanos-Ryan, Natalie. (2025). Age of onset of cannabis use and substance use problems: A systematic review of prospective studies.. Addictive behaviors, 163, 108259. https://doi.org/10.1016/j.addbeh.2025.108259
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