Large VA study found cannabis did not substantially reduce opioid use or improve PTSD in veterans | Research

The takeaway

Among 1,413 veterans with opioid use and PTSD, those who also used cannabis showed only marginally fewer opioid use days at baseline, and no differences in opioid use or PTSD symptoms at 4-month follow-up.

Veterans, VA clinicians, PTSD researchers, addiction policy analysts

No significant differences in opioid use or PTSD symptoms at 4-month follow-up

What the researchers found

Of 1,413 veterans with current non-medical opioid use, 30.3% also used cannabis. At baseline, cannabis co-users had slightly fewer opioid use days (small effect, p < .05) and slightly less severe PTSD (d = 0.16, p = .003). At 4-month follow-up, there were no significant differences in substance use or PTSD symptoms between groups.

Why it matters

Multiple states have authorized cannabis for PTSD and as an opioid substitute. This large veteran study provides longitudinal evidence that challenges both of these policy rationales.

The numbers in context

1,413 veterans with opioid use; 438 (30.3%) also used cannabis. Baseline: slightly fewer opioid days (small effect) and slightly less PTSD severity (d = 0.16) in cannabis users. Follow-up: no significant differences.

How the study worked

Nationwide longitudinal VA study (1992-2011) of veterans in specialized intensive PTSD treatment. Veterans with opioid use 7+ days/month were compared: those with cannabis co-use vs. those without. Assessed at admission and 4 months post-discharge.

What this study cannot tell us

Observational design; cannabis use was self-reported and not standardized; the population was in intensive PTSD treatment which may overshadow cannabis effects; historical data (1992-2011) may not reflect current cannabis products.

How to read the evidence

Large nationwide longitudinal VA dataset, though observational with self-reported cannabis use.

When this study was published

Published in 2020.

The bigger picture

Despite policy momentum toward authorizing cannabis for PTSD and opioid substitution, this large longitudinal dataset from the veteran population most affected by both conditions does not support substantial benefit.

Questions still open

Could specific cannabinoid formulations (high-CBD, controlled dosing) produce different results than self-directed cannabis use? Were the small baseline differences clinically meaningful?

Common questions

Does cannabis help veterans with PTSD?

In this large VA study, veterans who used cannabis alongside opioids showed only tiny baseline differences in PTSD severity compared to those who did not use cannabis, and no differences at follow-up. The authors conclude the data do not encourage cannabis use for either opioid reduction or PTSD treatment.

Can cannabis replace opioids?

This study found no substantial reduction in opioid use among veterans who also used cannabis. At 4-month follow-up, there was no significant difference in substance use patterns between the cannabis co-use and non-cannabis groups.

Read the original research

Impact of cannabis on non-medical opioid use and symptoms of posttraumatic stress disorder: a nationwide longitudinal VA study.

The American journal of drug and alcohol abuse, 46(6), 812-822

View on PubMed ↗Publisher’s paper ↗

Citation

De Aquino, Joao P; Sofuoglu, Mehmet; Stefanovics, Elina A; Rosenheck, Robert A. (2020). Impact of cannabis on non-medical opioid use and symptoms of posttraumatic stress disorder: a nationwide longitudinal VA study.. The American journal of drug and alcohol abuse, 46(6), 812-822. https://doi.org/10.1080/00952990.2020.1818248