Cannabis Use Changes How Immune Markers Predict 10-Year Psychosis Outcomes | Research

The takeaway

In a 10-year follow-up of 320 first-episode psychosis patients, most baseline immune markers only predicted outcomes among those who used cannabis, suggesting inflammation and cannabis interact in shaping psychosis trajectories.

Researchers studying psychosis biomarkers, clinicians working with first-episode psychosis patients, and anyone interested in cannabis-immune system interactions.

CRP, IL-1RA, and sgp130 predicted psychosis outcomes only in cannabis users

What the researchers found

Only sTNFR1 independently predicted lower risk of psychiatric readmission and psychotic episodes over 10 years. CRP, IL-1RA, and sgp130 only showed associations with outcomes in cannabis users. In cannabis users specifically, CRP and IL-1RA were linked to lower readmission risk, while sgp130 was linked to higher risk.

Why it matters

Immune markers have been proposed as predictors of psychosis outcomes, but this study shows those associations largely depend on whether someone uses cannabis. This complicates the use of inflammatory biomarkers in clinical prediction and highlights cannabis as a key moderating factor.

The numbers in context

320 first-episode psychosis patients; 10-year follow-up; 5 immune markers tested; only sTNFR1 predicted outcomes independently of cannabis; CRP, IL-1RA, and sgp130 effects were cannabis-dependent.

How the study worked

Longitudinal follow-up of 320 first-episode psychosis patients. Baseline blood immune markers (CRP, IL-1RA, sIL-2R, sTNFR1, sgp130) measured at entry. Outcomes tracked over 10 years: psychiatric readmissions, psychotic episodes per year, and change in positive symptom severity.

What this study cannot tell us

Observational design cannot establish causation. Cannabis use measured only at baseline, not tracked over 10 years. Immune markers also measured once at baseline. Specific cannabis types, doses, and frequency not captured.

How to read the evidence

Large sample with 10-year follow-up provides strong longitudinal data, but observational design and single-timepoint measurements limit causal inference.

When this study was published

2025 study with extended follow-up capturing a decade of psychosis outcomes.

The bigger picture

The finding that immune-psychosis links depend on cannabis use suggests these two factors may share biological pathways. It challenges the idea that inflammation alone drives psychosis course and points to cannabis-immune interactions as an underexplored mechanism.

Questions still open

Does cannabis directly alter immune marker levels in people with psychosis?
Would tracking cannabis use changes over time reveal different immune-psychosis patterns?

Common questions

Does cannabis cause worse psychosis outcomes through inflammation?

This study cannot establish causation, but it shows that immune markers and cannabis use interact in predicting outcomes, suggesting shared biological pathways that warrant further investigation.

Can blood tests predict psychosis outcomes?

Only sTNFR1 independently predicted better outcomes. Other immune markers were only predictive when cannabis use was factored in, complicating their standalone clinical utility.

Read the original research

Recent cannabis use affects the association between baseline immune markers and long-term outcomes in psychosis.

Translational psychiatry, 15(1), 282

View on PubMed ↗Publisher’s paper ↗

Citation

Kreis, Isabel; Fjelnseth Wold, Kristin; Åsbø, Gina; Bärthel Flaaten, Camilla; Engen, Magnus Johan; Lyngstad, Siv Hege; Hustad Widing, Line; Sheikh, Mashhood Ahmed; Frogner Werner, Maren Caroline; Bakken, Eivind; Ueland, Thor; Steen, Nils Eiel; Melle, Ingrid. (2025). Recent cannabis use affects the association between baseline immune markers and long-term outcomes in psychosis.. Translational psychiatry, 15(1), 282. https://doi.org/10.1038/s41398-025-03498-x