Systematically Testing the Evidence on Marijuana

Cannabis and posttraumatic stress disorder in Veterans

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Cannabis and Posttraumatic Stress Disorder in Veterans

By Melanie L. Hill, PhD1 and Sonya Norman, PhD2

U.S. military Veterans have high rates of posttraumatic stress disorder (PTSD) and are especially likely to report using cannabis for medical purposes, including the management of PTSD symptoms.

Efficacy of Cannabis for PTSD

  • The only RCT of smoked cannabis compared effects of 3 active cannabis preparations (12% THC vs 11% CBD vs 8% THC + 8% CBD; up to 1.8 g/day) with placebo on PTSD symptoms in 80 Veterans and found large reductions in symptoms across all groups (d = -1.30 [placebo], d = -1.99 [high THC], d= -0.79 [high CBD], d= -0.83 [THC + CBD]), but no significant differences between placebo and any active cannabis preparation.1 Given the relatively small sample size, larger trials are needed to replicate results.
    • This large placebo response may reflect high expectations held by Veterans that cannabis relieves PTSD symptoms, as identified in previous research surveying combat-experienced male Veterans.2
  • A randomized crossover study of nabilone (a synthetic cannabinoid) for PTSD-related nightmares in 10 active-duty military personnel tested effects of 0.5 mg, titrated to an effective dose of up to 3.0 mg, and found a decrease in frequency and intensity of recurring and distressing dreams.3 However, replication in larger studies is needed.
  • Findings from observational, longitudinal studies comparing changes in PTSD symptoms over time between groups using cannabis versus not using cannabis do not provide consistent evidence of associations between cannabis use and PTSD symptoms.
    • One study of Veterans in PTSD treatment found no difference between groups who used versus did not use cannabis in PTSD symptom change over 4 months,4 while another study found increased PTSD symptoms in the group using cannabis.5 A third study of Veterans and civilians found declining PTSD symptoms over a year in both groups, with a greater reduction in the group that used cannabis.6
  • A recent systematic review found that overall, cannabis may not have an effect on PTSD severity, and effects on specific PTSD symptoms are very uncertain.7
  • RCTs evaluating cannabis-based pharmaceuticals containing standardized doses and ratios of cannabinoids (e.g., THC, CBD) are underway, but do not yet have results.
  • Further, studies to date have included overwhelming majorities of male participants; as the relationship between PTSD and drug use may differ for men versus women,8 studies of female Veterans are needed to understand potential gender differences.

Clinical Considerations

  • Veterans with PTSD may experience cannabis-related problems; > 40% of Veterans with PTSD and recent cannabis use screen positive for cannabis use disorder (CUD).9
  • Frequent cannabis use is associated with experiencing withdrawal symptoms when attempting to quit using cannabis, such as anxiety, hostility, insomnia, and depressed mood.10 Adjusting for frequency of cannabis use, Veterans with versus without PTSD experience greater cannabis craving and withdrawal symptoms.11
  • Because of these concerns, PTSD treatment providers should screen for cannabis use and provide Veterans with information about possible risks of frequent cannabis use.
  • Because Veterans may hold expectations that cannabis is helpful for PTSD symptoms and self-medicate with cannabis, care should be taken to approach these conversations in a thoughtful and nonjudgmental manner that preserves the therapeutic alliance, while presenting the evidence in a realistic way.
  • Veterans with PTSD and CUD do not need to wait for a period of abstinence from cannabis use to benefit from evidence-based PTSD treatments. Trauma-focused treatments, such as Prolonged Exposure and Cognitive Processing Therapy, are effective for these patients and do not worsen substance use outcomes.12

Bottom Line

There is currently insufficient evidence from clinical trials supporting cannabis to treat PTSD. Some patients with PTSD may report experiencing short-term symptom relief when using cannabis, but PTSD symptom reduction did not differ between Veterans randomized to cannabis versus placebo in the only extant RCT. The long-term effects of cannabis use in Veterans with PTSD remain unclear. Some Veterans may experience worsening PTSD symptoms with chronic cannabis use and/or difficulty stopping cannabis use. Clinicians treating Veterans with PTSD should screen for and monitor Veterans’ cannabis use and should discuss possible risks versus benefits of using cannabis to manage PTSD symptoms.

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Citations

  1. Bonn-Miller MO, Sisley S, Riggs P, et al. The short-term impact of 3 smoked cannabis preparations versus placebo on PTSD symptoms: A randomized cross-over clinical trial. PLoS ONE. 2021;16(3):e0246990.
  2. Earleywine M, Bolles JR. Marijuana, expectancies, and post-traumatic stress symptoms: a preliminary investigation. J Psychoactive Drugs. 2014;46(3):171-177.
  3. Jetly R, Heber A, Fraser G, Boisvert D. The efficacy of nabilone, a synthetic cannabinoid, in the treatment of PTSD-associated nightmares: a preliminary randomized, double-blind, placebo-controlled cross-over design study. Psychoneuroendocrinology. 2015;51:585-588.
  4. De Aquino JP, Sofuoglu M, Stefanovics EA, Rosenheck RA. Impact of cannabis on non-medical opioid use and symptoms of posttraumatic stress disorder: a nationwide longitudinal VA study. Am J Drug Alcohol Abuse. 2020:1-11.
  5. Wilkinson ST, Stefanovics E, Rosenheck RA. Marijuana use is associated with worse outcomes in symptom severity and violent behavior in patients with posttraumatic stress disorder. J Clin Psychiatry. 2015;76(9):1174-1180.
  6. Bonn-Miller MO, Brunstetter M, Simonian A, et al. The long-term, prospective, therapeutic impact of cannabis on post-traumatic stress disorder. Cannabis Cannabinoid Res. 2022;7(2):214-223.
  7. Ayers C, Harrod C, Durbin S, et al. Cannabis for the management of symptoms of PTSD: A living systematic review. The Systematically Testing the Evidence on Marijuana Project. https://www.cannabisevidence.org/evidence-syntheses/ptsd/. Published 2021. Updated Dec 7, 2021. Accessed Mar 30, 2022.
  8. Livingston NA, Lee DJ, Mahoney CT, Farmer SL, Cole T, Marx BP, Keane TM. Longitudinal assessment of PTSD and illicit drug use among male and female OEF-OIF veterans. Addict Behav. 2021;118:106870.
  9. Hill ML, Loflin M, Nichter B, Norman SB, Pietrzak RH. Prevalence of cannabis use, disorder, and medical card possession in U.S. military veterans: results from the 2019-2020 National Health and Resilience in Veterans Study. Addict Behav. 2021;120:106963.
  10. Livne O, Shmulewitz D, Lev-Ran S, Hasin DS. DSM-5 cannabis withdrawal syndrome: demographic and clinical correlates in U.S. adults. Drug Alcohol Depend. 2019;195:170-177.
  11. Boden MT, Babson KA, Vujanovic AA, Short NA, Bonn-Miller MO. Posttraumatic stress disorder and cannabis use characteristics among military veterans with cannabis dependence. Am J Addict. 2013;22(3):277-284.
  12. Lancaster CL, Gros DF, Mullarkey MC, et al. Does trauma-focused exposure therapy exacerbate symptoms among patients with comorbid PTSD and substance use disorders? Behav Cogn Psychother. 2020;48(1):38-53.

Suggested citation: Hill ML, Norman S. Cannabis and posttraumatic stress disorder in Veterans. The Systematically Testing the Evidence on Marijuana Project. September 2022. https://www.cannabisevidence.org/clinician-resources/clinician-briefs/cannabis-and-posttraumatic-stress-disorder-in-veterans
Acknowledgments: Thank you to J. Cobb Scott, PhD and Mohini Ranganathan, MD for critically reviewing this document.
Author affiliations: 1UC San Diego School of Medicine; 2VA San Diego Healthcare System, UC San Diego School of Medicine, National Center for PTSD, and VA Center of Excellence for Stress and Mental Health