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Study breakdown

Cannabis Use Worsened PTSD Symptoms in Veterans, and PTSD Predicted Cannabis Disorder

Longitudinal CohortStrong evidence
The takeaway

In a longitudinal study of 361 veterans, cannabis use predicted worsening trauma intrusion symptoms over 6 months, while PTSD diagnosis predicted the development of cannabis use disorder over 12 months.

Veterans, PTSD clinicians, VA healthcare providers, addiction medicine specialists

Cannabis predicted worsening intrusions (beta=0.46)

What the researchers found

Using cross-lagged panel modeling, baseline cannabis use significantly predicted worse intrusion symptoms at 6 months (beta=0.46). The reverse association (intrusions predicting use) was weaker (beta=0.22). PTSD diagnosis at baseline predicted cannabis use disorder at 12 months (beta=0.15), but CUD did not significantly predict PTSD.

Why it matters

Many veterans use cannabis to self-medicate PTSD, but this study suggests cannabis may actually worsen the core intrusive symptoms of PTSD over time, creating a self-reinforcing cycle.

The numbers in context

361 veterans; 3 timepoints (baseline, 6mo, 12mo); cannabis to intrusions beta=0.46; intrusions to cannabis beta=0.22; PTSD to CUD beta=0.15

How the study worked

Prospective longitudinal study of 361 post-9/11 veterans with assessments at baseline, 6 months, and 12 months using random intercept cross-lagged panel models to distinguish within-person changes from between-person differences.

What this study cannot tell us

Observational study, though the cross-lagged design provides stronger causal inference than cross-sectional data. Sample limited to post-9/11 veterans.

How to read the evidence

Prospective longitudinal design with cross-lagged panel modeling provides stronger causal inference than most observational studies.

When this study was published

Published in 2022

The bigger picture

The bidirectional relationship between cannabis use and PTSD has significant implications for veteran health policy. If cannabis worsens PTSD while PTSD drives cannabis use, both conditions may escalate together.

Questions still open

  • Would CBD-dominant products have a different effect on PTSD intrusion symptoms than THC-dominant cannabis? Could targeted interventions break the cannabis-PTSD cycle?

Common questions

Does cannabis help or worsen PTSD?
This study found cannabis use predicted worsening of trauma intrusion symptoms at 6 months (beta=0.46), suggesting that despite subjective relief, cannabis may actually make core PTSD symptoms worse over time.
Is there a cycle between PTSD and cannabis use?
Yes. The study found a bidirectional relationship: cannabis worsened intrusive PTSD symptoms, while PTSD predicted development of cannabis use disorder, suggesting a self-reinforcing cycle.

Read the original research

Cannabis use and posttraumatic stress disorder: prospective evidence from a longitudinal study of veterans.

Psychological medicine, 52(3), 446-456

Citation

Metrik, Jane; Stevens, Angela K; Gunn, Rachel L; Borsari, Brian; Jackson, Kristina M. (2022). Cannabis use and posttraumatic stress disorder: prospective evidence from a longitudinal study of veterans.. Psychological medicine, 52(3), 446-456. https://doi.org/10.1017/S003329172000197X

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