Table of Contents
- #9 Cannabis use and trauma-focused treatment for co-occurring posttraumatic stress disorder and substance use disorders: A meta-analysis of individual patient data.
- What This Study Teaches Us
- Why This Matters Clinically
- Study Snapshot
- Where This Paper Deserves Skepticism
- Dr. Caplan’s Take
- Clinical Bottom Line
Clinical Takeaway
People with PTSD and co-occurring substance use disorders who also use cannabis can still benefit meaningfully from trauma-focused treatments, and cannabis use does not appear to undermine treatment effectiveness compared to non-users. Clinicians should not withhold or delay evidence-based trauma-focused care for patients simply because they report cannabis use alongside other substance use disorders.
#9 Cannabis use and trauma-focused treatment for co-occurring posttraumatic stress disorder and substance use disorders: A meta-analysis of individual patient data.
Citation: Hill Melanie L et al.. Cannabis use and trauma-focused treatment for co-occurring posttraumatic stress disorder and substance use disorders: A meta-analysis of individual patient data.. Journal of anxiety disorders. 2024. PMID: 38266511.
Design: 6 Journal: 0 N: 4 Recency: 1 Pop: 2 Human: 1 Risk: -2
- Preclinical only
Abstract: High rates of cannabis use among people with posttraumatic stress disorder (PTSD) have raised questions about the efficacy of evidence-based PTSD treatments for individuals reporting cannabis use, particularly those with co-occurring alcohol or other substance use disorders (SUDs). Using a subset of four randomized clinical trials (RCTs) included in Project Harmony, an individual patient meta-analysis of 36 RCTs (total N = 4046) of treatments for co-occurring PTSD+SUD, we examined differences in trauma-focused (TF) and non-trauma-focused (non-TF) treatment outcomes for individuals who did and did not endorse baseline cannabis use (N = 410; 70% male; 33.2% endorsed cannabis use). Propensity score-weighted mixed effects modeling evaluated main and interactive effects of treatment assignment (TF versus non-TF) and baseline cannabis use (yes/no) on attendance rates and within-treatment changes in PTSD, alcohol, and non-cannabis drug use severity. Results revealed significant improvements across outcomes among participants in all conditions, with larger PTSD symptom reductions but lower attendance among individuals receiving TF versus non-TF treatment in both cannabis groups. Participants achieved similar reductions in alcohol and drug use across all conditions. TF outperformed non-TF treatments regardless of recent cannabis use, underscoring the importance of reducing barriers to accessing TF treatments for individuals reporting cannabis use.
What This Study Teaches Us
Trauma-focused psychotherapy remains more effective than non-trauma-focused approaches for PTSD symptoms even in patients who use cannabis, and cannabis use does not appear to meaningfully impair treatment response. However, people using cannabis show lower treatment attendance rates, suggesting engagement rather than efficacy is the challenge.
Why This Matters Clinically
Many clinicians hesitate to refer PTSD patients who use cannabis to evidence-based trauma-focused therapy, assuming cannabis use will undermine treatment. This data suggests that assumption is unfounded, though it does highlight that retention strategies matter. For patients and clinicians, it supports offering trauma-focused treatment while being proactive about attendance barriers.
Study Snapshot
| Study Design | Individual patient meta-analysis of 4 RCTs nested within Project Harmony (36 RCTs total); propensity score-weighted mixed effects modeling |
| Population | N=410 (70% male) with co-occurring PTSD and substance use disorders; 33.2% endorsed baseline cannabis use |
| Intervention | Trauma-focused (TF) versus non-trauma-focused (non-TF) psychotherapies for PTSD and SUD; duration and specific protocols not detailed in abstract |
| Primary Outcome | Treatment attendance rates and within-treatment changes in PTSD severity, alcohol use severity, and non-cannabis drug use severity |
| Key Result | TF treatments produced larger PTSD symptom reductions than non-TF treatments in both cannabis-using and non-cannabis-using groups; cannabis users showed lower attendance rates but equivalent drug and alcohol use reductions across all conditions |
Where This Paper Deserves Skepticism
The abstract provides minimal detail on the individual trials contributing to this analysis, their quality, or their heterogeneity, making it hard to judge whether these were comparable studies. The cannabis use measure is binary and baseline only, so we do not know current use intensity, frequency, or how cannabis use patterns changed during treatment. With only 410 participants and 33% in the cannabis group, subgroup power may be limited. The abstract does not specify whether dropout was analyzed as a mediator of outcome or whether lower attendance actually explained the retained effect of TF treatment.
Dr. Caplan’s Take
This meta-analysis gives me useful reassurance that trauma-focused CBT and prolonged exposure work for PTSD in people who use cannabis, and that we should not withhold evidence-based care based on cannabis use alone. That said, the attendance gap is real and clinically important, so I need to think harder about what makes people drop out. Whether that is cannabis intoxication during sessions, shame, or something else remains unclear from this data, and I should be screening for and addressing the actual barriers in front of me rather than making assumptions.
Clinical Bottom Line
Offer trauma-focused PTSD treatment to patients who use cannabis, as it outperforms less intensive approaches even in that group. Plan proactively for retention challenges, which appear more significant than treatment efficacy problems in this population.
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