What topics does this cannabis study cover?

This study covers research on: Mental Health, Addiction.

Where was this research published?

Published in Biological psychiatry on August 18, 2026.

Cannabis linked to earlier psychosis onset, especially later in life

Q: What did this research study find?

Across **149 studies**, *cannabis use* was associated with psychosis onset occurring an average of **2.50 years earlier** than in nonusers.

Cannabis Use and Age-Related Acceleration of Psychosis Onset: A Meta-Analysis.

Biological psychiatry • August 18, 2026 • Highly Relevant

🤖

AI Summary

This updated meta-analysis combined findings from 149 studies involving 18,272 cannabis users and 52,801 nonusers. Across the included research, cannabis use was associated with psychosis beginning an average of 2.50 years earlier than in nonusers. Because the studies were observational, this association does not by itself prove that cannabis directly causes earlier psychosis onset.

The age pattern was especially notable. In samples where psychosis typically began before age 20, researchers found no difference in onset age between cannabis users and nonusers. However, the gap increased among samples with older average onset ages: 1.60 years earlier for ages 20 to under 25, 4.43 years earlier for ages 25 to under 30, and 6.30 years earlier at age 30 or older. The authors conclude that the link is robust and supports clearer public-health warnings about potential psychiatric risks associated with cannabis use across the lifespan.

💡 Key Findings

Across 149 studies, cannabis use was associated with psychosis onset occurring an average of 2.50 years earlier than in nonusers.

High

90%

The age-related difference increased in older-onset samples, reaching 6.30 years earlier among cannabis users in samples with a mean onset age of 30 or older.

High

90%

In samples with a mean psychosis onset age below 20, there was no difference in onset age between cannabis users and nonusers.

High

85%

The findings support consideration of public-health warnings about potential psychiatric risks associated with cannabis use across the lifespan, although the observational evidence does not establish causation.

High

80%

📄 Original Abstract

Increases in cannabis use, potency, and legal liberalization have raised concerns about psychiatric consequences. Previous studies suggest an association between cannabis use and earlier age at onset (AAO) of psychosis, but an updated meta-analysis is needed. MEDLINE, Embase, and PsycInfo were searched from inception to April 2025. Peer-reviewed cohort and case-control studies reporting mean and standard deviation of AAO of psychosis in cannabis users and nonusers or other effect size data were included. Pooled standardized mean difference was calculated using random-effects meta-analysis. Subgroup analyses used mixed effects models, and between-study heterogeneity was examined with random-effects meta-regression. The main meta-analysis included 181 samples from 149 studies, comprising 18,272 cannabis users and 52,801 nonusers. Cannabis use was associated with a mean earlier AAO of 2.50 years. Subgroup analysis by sample mean onset age found no difference in AAO of psychosis between cannabis users and nonusers in the <20-year-old group, but there was a progressive age-related difference; cannabis users in the 20 to <25, 25 to <30, and ≥30 groups had an earlier AAO of 1.60, 4.43, and 6.30 years, respectively. Multiple meta-regression indicated that sample mean onset age was a strong and statistically independent moderator of earlier AAO effect size (z = -7.59, p < .0001). The association between cannabis use and earlier psychosis onset is robust, with larger effect sizes in samples with later mean age of psychosis onset. These findings support consideration of public health warnings of the potential psychiatric risks associated with cannabis use across the lifespan.

Paper Type

📄 Research

Publication

Journal: Biological psychiatry
Published: August 18, 2026
PMID: 42610992
DOI: 10.1016/j.biopsych.2026.06.025

Authors (3)

Carly Stevens Discipline of Psychiatry and Mental Health, University of New South Wales, Sydney, New South Wales, Australia.
Hannah Pincham Discipline of Psychiatry and Mental Health, University of New South Wales, Sydney, New South Wales, Australia; Mental Health Services, Prince of Wales Hospital, Randwick, New South Wales, Australia.
Matthew Large Discipline of Psychiatry and Mental Health, University of New South Wales, Sydney, New South Wales, Australia; Mental Health Services, Prince of Wales Hospital, Randwick, New South Wales, Australia; Mindgardens Neuroscience Network, Randwick Campus, South Eastern Sydney Local Health District, Randwick, New South Wales, Australia. Electronic address: mmclarge@gmail.com.