This study provides preliminary epidemiological evidence that cannabis use may contribute to reducing the association between post-traumatic stress disorder and severe depressive and suicidal states. There is an emerging need for high-quality experimental investigation of the efficacy of cannabis/cannabinoids for the treatment of post-traumatic stress disorder.

Among 24,089 eligible respondents, 420 (1.7%) reported a current clinical diagnosis of post-traumatic stress disorder. In total, 106 (28.2%) people with post-traumatic stress disorder reported past-year cannabis use, compared to 11.2% of those without post-traumatic stress disorder ( p < 0.001). In multivariable analyses, post-traumatic stress disorder was significantly associated with recent major depressive episode (adjusted odds ratio = 7.18, 95% confidence interval: 4.32–11.91) and suicidal ideation (adjusted odds ratio = 4.76, 95% confidence interval: 2.39–9.47) among cannabis non-users. post-traumatic stress disorder was not associated with either outcome among cannabis-using respondents (both p > 0.05).

We used data from the 2012 Canadian Community Health Survey-Mental Health, a nationally representative cross-sectional survey of non-institutionalized Canadians aged ⩾15 years. The relationship between post-traumatic stress disorder and each outcome was modelled using logistic regression with an interaction term for cannabis and post-traumatic stress disorder, controlling for demographic characteristics, mental health, and substance use comorbidities. The ratio of odds ratios and relative excess risk due to interaction was calculated to measure interaction on the multiplicative and additive scales, respectively.

Post-traumatic stress disorder sharply increases the risk of depression and suicide. Individuals living with post-traumatic stress disorder frequently use cannabis to treat associated symptoms. We sought to investigate whether cannabis use modifies the association between post-traumatic stress disorder and experiencing a major depressive episode or suicidal ideation.

References

Boden, MT, Babson, KA, Vujanovic, AA, et al . ( 2013 ) Posttraumatic stress disorder and cannabis use characteristics among military veterans with cannabis dependence . Am J Addict 22: 277 – 284 .

Google Scholar Crossref | Medline

Bonn-Miller, M, Boden, M, Vujanovic, A, et al . ( 2013 ) Prospective investigation of the impact of cannabis use disorders on posttraumatic stress disorder symptoms among veterans in residential treatment . Psychol Trauma 5: 193 – 200 .

Google Scholar Crossref

Bonn-Miller, MO, Babson, KA, Vandrey, R ( 2014 ) Using cannabis to help you sleep: Heightened frequency of medical cannabis use among those with PTSD . Drug Alcohol Depend 136: 162 – 165 .

Google Scholar Crossref | Medline

Bonn-Miller, MO, Vujanovic, AA, Feldner, MT, et al . ( 2007 ) Posttraumatic stress symptom severity predicts marijuana use coping motives among traumatic event-exposed marijuana users . J Trauma Stress 20: 577 – 586 .

Google Scholar Crossref | Medline | ISI

Bordieri, MJ, Tull, MT, McDermott, MJ, et al . ( 2014 ) The moderating role of experiential avoidance in the relationship between posttraumatic stress disorder symptom severity and cannabis dependence . J Contextual Behav Sci 3: 273 – 278 .

Google Scholar Crossref | Medline

Bremner, JD ( 2006 ) Traumatic stress: Effects on the brain . Dialogues Clin Neurosci 8: 445 – 461 .

Google Scholar Medline

Clinicaltrials.gov . ( 2015 ) Evaluating Safety and Efficacy of Cannabis in Participants With Chronic Posttraumatic Stress Disorder. Available at: https://clinicaltrials.gov/ct2/show/results/NCT02517424 (accessed 30 January 2018).

Google Scholar

Cougle, JR, Bonn-Miller, MO, Vujanovic, AA, et al . ( 2011 ) Posttraumatic stress disorder and cannabis use in a nationally representative sample . Psychol Addict Behav 25: 554 – 558 .

Google Scholar Crossref | Medline | ISI

D’Aliesio, R ( 2017 ) Veterans Face Much Higher Suicide Rate than Civilians. Available at: https://www.theglobeandmail.com/news/national/veterans-dying-by-suicide-at-significantly-higher-rate-than-general-population-study/article37237508/ (accessed 3 April 2018).

Google Scholar

Duckers, ML, Alisic, E, Brewin, CR ( 2016 ) A vulnerability paradox in the cross-national prevalence of post-traumatic stress disorder . Br J Psychiatry 209: 300 – 305 .

Google Scholar Crossref | Medline

Earleywine, M, Bolles, JR ( 2014 ) Marijuana, expectancies, and post-traumatic stress symptoms: A preliminary investigation . J Psychoactive Drugs 46: 171 – 177 .

Google Scholar Crossref | Medline

Fraser, GA ( 2009 ) The use of a synthetic cannabinoid in the management of treatment-resistant nightmares in posttraumatic stress disorder (PTSD) . CNS Neurosci Ther 15: 84 – 88 .

Google Scholar Crossref | Medline | ISI

Freeman, D, Thompson, C, Vorontsova, N, et al . ( 2013 ) Paranoia and post-traumatic stress disorder in the months after a physical assault: A longitudinal study examining shared and differential predictors . Psychol Med 43: 2673 – 2684 .

Google Scholar Crossref | Medline

Gentes, EL, Schry, AR, Hicks, TA, et al . ( 2016 ) Prevalence and correlates of cannabis use in an outpatient VA posttraumatic stress disorder clinic . Psychol Addict Behav 30: 415 – 421 .

Google Scholar Crossref | Medline

Gradus, JL, Qin, P, Lincoln, AK, et al . ( 2010 ) Posttraumatic stress disorder and completed suicide . Am J Epidemiol 171: 721 – 727 .

Google Scholar Crossref | Medline | ISI

Greer, GR, Grob, CS, Halberstadt, AL ( 2014 ) PTSD symptom reports of patients evaluated for the New Mexico Medical Cannabis Program . J Psychoactive Drugs 46: 73 – 77 .

Google Scholar Crossref | Medline

Hillard, CJ ( 2015 ) The endocannabinoid signaling system in the CNS: A primer . Int Rev Neurobiol. 125: 1 – 47 .

Google Scholar Crossref | Medline

Hosmer, DW, Lemeshow, S ( 1992 ) Confidence interval estimation of interaction . Epidemiology 3: 452 – 456 .

Google Scholar Crossref | Medline | ISI

Jetly, R, Heber, A, Fraser, G, et al . ( 2015 ) 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 51: 585 – 588 .

Google Scholar Crossref | Medline | ISI

Kevorkian, S, Bonn-Miller, MO, Belendiuk, K, et al . ( 2015 ) Associations among trauma, posttraumatic stress disorder, cannabis use, and cannabis use disorder in a nationally representative epidemiologic sample . Psychol Addict Behav 29: 633 – 638 .

Google Scholar Crossref | Medline

Knol, MJ, VanderWeele, TJ ( 2012 ) Recommendations for presenting analyses of effect modification and interaction . Int J Epidemiol 41: 514 – 520 .

Google Scholar Crossref | Medline | ISI

Knol, MJ, VanderWeele, TJ, Groenwold, RHH, et al . ( 2011 ) Estimating measures of interaction on an additive scale for preventive exposures . Eur J Epidemiol 26: 433 – 443 .

Google Scholar Crossref | Medline

Neumeister, A, Normandin, MD, Pietrzak, RH, et al . ( 2013 ) Elevated brain cannabinoid CB1 receptor availability in post-traumatic stress disorder: A positron emission tomography study . Mol Psychiatry 18: 1034 – 1040 .

Google Scholar Crossref | Medline | ISI

O’Neil, ME, Nugent, SM, Morasco, BJ, et al . ( 2017 ) Benefits and harms of plant-based cannabis for posttraumatic stress disorder: A systematic review . Ann Intern Med 167: 332 – 340 .

Google Scholar Crossref | Medline

Pai, A, Suris, AM, North, CS ( 2017 ) Posttraumatic stress disorder in the DSM-5: Controversy, change, and conceptual considerations . Behav Sci 7: 7 – 14 .

Google Scholar Crossref

Passie, T, Emrich, HM, Karst, M, et al . ( 2012 ) Mitigation of post-traumatic stress symptoms by Cannabis resin: A review of the clinical and neurobiological evidence . Drug Test Anal 4: 649 – 659 .

Google Scholar Crossref | Medline

Pineles, SL, Mostoufi, SM, Ready, CB, et al . ( 2011 ) Trauma reactivity, avoidant coping, and PTSD symptoms: A moderating relationship? J Abnorm Psychol 120: 240 – 246 .

Google Scholar Crossref | Medline | ISI

Ramsawh, HJ, Fullerton, CS, Mash, HB, et al . ( 2014 ) Risk for suicidal behaviors associated with PTSD, depression, and their comorbidity in the U.S. Army . J Affect Disord 161: 116 – 122 .

Google Scholar Crossref | Medline

Reinarman, C, Nunberg, H, Lanthier, F, et al . ( 2011 ) Who are medical marijuana patients? Population characteristics from nine California assessment clinics . J Psychoactive Drugs 43: 128 – 135 .

Google Scholar Crossref | Medline | ISI

Richardson, JD, Thompson, A, King, L, et al . ( 2017 ) Insomnia, psychiatric disorders and suicidal ideation in a national representative sample of active Canadian Forces members . BMC Psychiatry 17: 211 – 221 .

Google Scholar Crossref | Medline

Roitman, P, Mechoulam, R, Cooper-Kazaz, R, et al . ( 2014 ) Preliminary, open-label, pilot study of add-on oral Delta9-tetrahydrocannabinol in chronic post-traumatic stress disorder . Clin Drug Investig 34: 587 – 591 .

Google Scholar Crossref | Medline

Ruglass, LM, Shevorykin, A, Radoncic, V, et al . ( 2017 ) Impact of cannabis use on treatment outcomes among adults receiving cognitive-behavioral treatment for PTSD and substance use disorders . J Clin Med 6: E14 .

Google Scholar Crossref | Medline

Serrano, A ( 2018 ) As Vets Demand Cannabis for PTSD, Science Races to Unlock Its Secrets. Available at: https://www.scientificamerican.com/article/as-vets-demand-cannabis-for-ptsd-science-races-to-unlock-its-secrets/ (accessed 3 April 2018).

Google Scholar

Shalev, A, Liberzon, I, Marmar, C ( 2017 ) Post-traumatic stress disorder . New Engl J Med 376: 2459 – 2469 .

Google Scholar Crossref | Medline | ISI

Solowij, N, Lorenzetti, V, Yücel, M ( 2016 ) Effects of cannabis use on human behavior: A call for standardization of cannabis use metrics . JAMA Psychiatry 73: 995 – 996 .

Google Scholar Crossref | Medline

Statistics Canada ( 2013 ) Canadian Community Health Survey - Mental Health (CCHS). Available at: http://www23.statcan.gc.ca/imdb/p2SV.pl?Function=getSurvey&SDDS=5015 (accessed 10 October 2017).

Google Scholar

Steenkamp, MM, Blessing, EM, Galatzer-Levy, IR, et al . ( 2017 ) Marijuana and other cannabinoids as a treatment for posttraumatic stress disorder: A literature review . Depress Anxiety 34: 207 – 216 .

Google Scholar Crossref | Medline

The University of British Columbia Board of Governors ( 2012 ) Research Involving Human Participants (Policy 89). Available at: http://universitycounsel.ubc.ca/files/2012/06/policy89.pdf (accessed 2 December 2017).

Google Scholar

Trezza, V, Campolongo, P ( 2013 ) The endocannabinoid system as a possible target to treat both the cognitive and emotional features of post-traumatic stress disorder (PTSD) . Front Behav Neurosci 7: 100 .

Google Scholar Crossref | Medline

Tsai, J, Harpaz-Rotem, I, Pilver, CE, et al . ( 2014 ) Latent class analysis of personality disorders in adults with posttraumatic stress disorder: Results from the National Epidemiologic Survey on Alcohol and Related Conditions . J Clin Psychiatry 75: 276 – 284 .

Google Scholar Crossref | Medline

VanderWeele, TJ, Knol, MJ ( 2014 ) A tutorial on interaction . Epidemiol Methods 3: 33 – 72 .

Google Scholar Crossref

Veterans Affairs Canada ( 2019 ) Cannabis for Medical Purposes. Available at: http://www.veterans.gc.ca/eng/news/vac-responds/just-the-facts/cannabis-medical-purposes (accessed 8 October 2019).

Google Scholar

Wilkinson, ST, Stefanovics, E, Rosenheck, RA ( 2015 ) Marijuana use is associated with worse outcomes in symptom severity and violent behavior in patients with posttraumatic stress disorder . J Clin Psychiatry 76: 1174 – 1180 .

Google Scholar Crossref | Medline