A systematic review of 62 studies found the combination of childhood adversity and cannabis use amplified psychosis risk up to 31-fold in first-episode patients, far exceeding either risk factor alone.
Child psychiatrists, trauma therapists, school counselors working with at-risk youth, public health prevention planners.
Combined risk: up to 31-fold in first-episode psychosis
What the researchers found
Across 62 studies in five population categories, childhood adversity and cannabis use showed synergistic psychosis risk amplification: odds ratios up to 20.9 in community samples and 31.0 in first-episode samples. Patients with combined exposure had earlier onset (2.9-3.6 years earlier), more severe positive symptoms, reduced treatment response, and poorer functional outcomes. Evidence supports a developmental cascade model where trauma creates neurobiological vulnerability that cannabis exposure exploits.
Why it matters
Neither childhood trauma nor cannabis use alone fully explains psychosis risk. This review demonstrates their combination is far more dangerous than either factor in isolation, with risk multiplication rather than simple addition. This has profound implications for screening and prevention: identifying youth with trauma histories who also use cannabis could target the highest-risk individuals.
The numbers in context
62 studies. Community OR up to 20.9. First-episode OR up to 31.0. Earlier onset: 2.9-3.6 years. Neurobiological mechanisms: HPA axis, inflammation, ECS dysfunction. Trauma-informed interventions show promising results.
How the study worked
Systematic review of literature from January 2000-January 2024 across PubMed/MEDLINE, PsycINFO, Embase, and Web of Science. 62 studies categorized into five groups: general population (15), high-risk (5), first-episode psychosis (18), established psychosis (11), and treatment-seeking clinical/intervention studies (13). Quality assessed with appropriate tools.
What this study cannot tell us
Observational studies predominate. Cannot fully establish causation. Heterogeneous definitions of childhood adversity and cannabis use across studies. Possible recall bias in retrospective trauma assessment. Shared confounders (poverty, family dysfunction) may inflate risk estimates.
How to read the evidence
Strong: comprehensive systematic review of 62 studies with consistent findings across five population categories and convergent neurobiological evidence.
When this study was published
2025 study
The bigger picture
The developmental cascade model, where trauma primes the brain for cannabis-triggered psychosis, has profound implications for prevention. Rather than targeting all cannabis users, focusing on those with trauma histories could maximize the impact of limited prevention resources.
Questions still open
- At what developmental window is the trauma-cannabis interaction most dangerous? Would trauma-informed cannabis prevention programs reduce psychosis incidence? Can neuroimaging identify the "primed" brain state that makes cannabis exposure more dangerous?
Common questions
Is cannabis more dangerous for people with childhood trauma?
Why does trauma make cannabis more dangerous?
Read the original research
Co-occurrence between adverse childhood experiences and cannabis use in psychosis risk and course: A stratified systematic review.
Journal of psychiatric research, 190, 387-399
Citation
Ricci, Valerio; De Berardis, Domenico; Martinotti, Giovanni; Maina, Giuseppe. (2025). Co-occurrence between adverse childhood experiences and cannabis use in psychosis risk and course: A stratified systematic review.. Journal of psychiatric research, 190, 387-399. https://doi.org/10.1016/j.jpsychires.2025.08.015
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