Cannabis Use and PTSD Among Veterans - PTSD: National Center for PTSD
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Cannabis Use and PTSD Among Veterans

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Cannabis Use and PTSD Among Veterans

Melanie Hill, PhD, Mallory Loflin, PhD, Kendall Browne, PhD, & Sonya D. Norman, PhD

Cannabis use for medical conditions is an issue of growing interest and concern. Some Veterans use cannabis to relieve symptoms of PTSD and several states specifically approve the use of medical cannabis for PTSD. However, research to date does not support cannabis as an effective PTSD treatment, and some studies suggest cannabis can be harmful, particularly when used for long periods of time. Given these concerns, cannabis is not recommended for the treatment of PTSD.

Epidemiology of Cannabis Use and Cannabis Use Disorder (CUD) Among Veterans

Cannabis use in the general population has increased over the past decade. From 2013 to 2018, the number of Americans over the age of 12 reporting past month cannabis use rose from 19.8 million to 27.7 million (1,2). Likewise, daily use has increased 60% in the prior decade (1,2). Cannabis use among U.S. military Veterans has also increased. In 2014, 9% of Veterans in the U.S. reported using cannabis in the past year (3). In 2019-2020, the prevalence of past-6-month cannabis use among Veterans was 11.9%, and was over 20% among Veterans aged 18-44 (4).

A number of factors are associated with increased risk of cannabis use, including diagnosis of mental health problems such as PTSD (5), anxiety disorders , mood disorders and other substance use disorders (6).

Cannabis use disorder (CUD) which is an extended problematic use of cannabis is also common. At the start of 2020, lifetime prevalence of CUD among Veterans was 9.2% and the prevalence of past-6-month CUD diagnoses among Veterans was 2.7% (7). However, rates of current CUD are considerably higher among the subset of Veterans with co-occurring PTSD (12.1%), as well as among Veterans with other psychiatric and substance use problems (8.9%-13.0%; 4).

Problems Associated with Cannabis Use

Cannabis use is associated with medical and psychiatric problems. These problems may be caused by using cannabis, particularly if use is frequent, chronic and begins in adolescence. However, these problems also may reflect the characteristics of the people who use cannabis frequently. Medical problems include chronic bronchitis (8), abnormal brain development among early adolescent initiators (9), and impairment in short-term memory, motor coordination and the ability to perform complex psychomotor tasks such as driving (10). Psychiatric problems include psychosis (which is especially likely in genetically vulnerable populations; (11), depression and suicidality (6), as well as impairment in cognitive ability. Quality of life can also be affected as frequent, chronic cannabis use is prospectively related with decreased educational attainment, financial strain and antisocial behavior (12). Chronic cannabis use also can lead to dependence, with an established and clinically significant withdrawal syndrome (13).

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Active Ingredients and Route of Administration

The cannabis plant contains a variety of components (cannabinoids, terpenes), most notably delta-9-tetrahydrocannabinol (THC), which is the primary psychoactive compound. The potency of cannabis (i.e., concentration of THC) can vary substantially. For example, the percentage of THC in the cannabis plant can range in strength from less than 1% to well over 30% based upon strain and cultivation methods. In general, the potency of THC in the cannabis plant has increased as much as 10-fold over the past 40 years (14,15). In addition to THC, the cannabis plant contains numerous other cannabinoids, such as cannabidiol (CBD), cannabinol (CBN), and cannabigerol (CBG). The effects of cannabis use (e.g., experience of a high, anxiety, sleep) appear to vary as a function of both the concentration of cannabinoids in the plant (such as the percentage of THC) and the ratios between concentrations of different cannabinoids (such as the ratio of THC to CBD).

In addition to whole plant cannabis, a variety of cannabis extract products have been produced and sold in recent years, such as waxes, tinctures and oils. The concentration of THC in these products can be as high as 90%. Thus, an individual could unknowingly consume a very high dose of THC in one administration, which increases the risk of an adverse reaction (such as dizziness, anxiety or tachycardia).

Administration of different cannabis products (e.g., flower, hash, oil, wax, food products, tinctures) also can take different routes: inhalation (smoking or vaporizing), ingestion and topical application. Given the same concentration/ratio of cannabinoids, smoking or vaporizing cannabis produces similar effects (16); however, ingesting the same dose results in a delayed onset and longer duration of effect (17). Not all cannabis users may be aware of the delayed effect caused by ingestion, which may result in greater consumption and a stronger effect than intended.

Finally, cannabis-based pharmaceuticals, such as Sativex® (nabiximols) and Epidiolex® (CBD extract), have also been produced and studied in clinical trials. These products differ from whole plant cannabis and cannabis extracts that are sold commercially. Because cannabis-based pharmaceuticals contain specified concentrations of specific cannabinoids, research on the effects of these medications cannot be generalized to use of whole plant cannabis or other cannabis products.

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Neurobiology

Research has consistently demonstrated that the human endocannabinoid system plays a significant role in PTSD. People with PTSD have greater availability of cannabinoid type 1 (CB1) receptors as compared to trauma-exposed or healthy controls (18,19). As a result, cannabis use by individuals with PTSD could produce short-term reductions of PTSD symptoms. However, data suggest that continued use of cannabis among individuals with PTSD may lead to a number of negative consequences, including development of cannabis tolerance (via reductions in CB1 receptor density and/or efficiency) and dependence (20). Though recent work has shown that CB1 receptors may return after periods of marijuana abstinence (21), individuals with PTSD may have particular difficulty quitting, as is described below (22).

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Cannabis as a Treatment for PTSD

The belief that cannabis can be used to treat PTSD is primarily based on anecdotal evidence from individuals with PTSD who report that cannabis helps with their symptoms or improves their overall life and functioning. Randomized controlled trials (RCTs), which are a necessary "gold standard" for determining safety and efficacy, are needed to test the use of whole plant cannabis to treat PTSD. There has only been 1 RCT comparing whole plant cannabis and placebo for treating PTSD (23). This trial included 2 phases. The first phase compared effects of 3 active cannabis preparations (high THC, high5 CBD, balanced THC+CBD) and placebo on PTSD symptoms in 80 U.S. military Veterans. Results showed no significant difference in PTSD symptom reduction between placebo and any of the active cannabis preparations. In the second phase, 74 Veterans were re-randomized to receive 1 of 3 active cannabis preparations. Results showed a significant reduction in PTSD symptoms in the THC+CBD group only; however, because there was no placebo group in this phase, it is not possible to draw conclusions about the efficacy of cannabis to treat PTSD from these results.

Furthermore, evidence about the relationship over time between whole plant cannabis use and PTSD symptoms is mixed. One recent study comparing cannabis users to non-using controls found that cannabis users reported greater improvements in PTSD symptoms when observed over the course of a year. However, this study recruited individuals who endorsed already using cannabis to treat their PTSD symptoms before enrolling in the study. Because these individuals were not initiating cannabis as a novel treatment, it is somewhat surprising that their PTSD symptoms abated at the initiation of the study, rather than earlier in the course of their cannabis use. It is possible that including individuals who believed cannabis to be helpful for their PTSD may have selected for participants who were more likely to report greater symptom improvement related to their cannabis use. In addition, the study did not control for other variables that could explain differences in symptom reduction between the groups, leading to a high risk of bias (24). Meanwhile, another study found that medical cannabis users with self-reported PTSD experienced short-term symptom relief when using cannabis but no long-term changes in PTSD symptoms, suggesting that cannabis may not effectively treat PTSD (25). In addition, other research shows that chronic cannabis use might worsen trauma-related symptoms over time (26).

Preliminary studies suggest that oral CBD might decrease anxiety in those with and without clinical anxiety (27). This work has led to the development and testing of CBD treatments for individuals with social anxiety (28) and PTSD (29).

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Impact of Problematic Cannabis Use on PTSD Treatment

Chronic or problematic cannabis use might negatively impact Veterans' outcomes in evidence-based treatments for PTSD. Evidence suggests that a diagnosis of CUD predicts less symptom change during residential PTSD treatment (30) and continuing or starting to use cannabis after PTSD treatment has been linked to increased PTSD symptoms (31). However, other studies have found no association between baseline cannabis use and post-treatment PTSD symptoms (32,33). It is possible that functional problems related to cannabis use, rather than a neurobiological effect of cannabis, might impact PTSD treatment effectiveness. Individuals using cannabis may also have more difficulties engaging in treatment; a recent study found that baseline cannabis use predicted a doubled risk of dropout from both cognitive-behavioral and pharmacological treatments for PTSD, as well as poor adherence to trauma-focused psychotherapy (33).

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Treatment for Cannabis Addiction

People with PTSD have particular difficulty stopping their use of cannabis and responding to treatment for CUD. They have greater craving and withdrawal than those without PTSD (34) and greater likelihood of cannabis use during the 6 months following a quit attempt (35). However, these individuals can benefit from the many evidence-based treatments for CUD, including cognitive behavioral therapy, motivational enhancement, and contingency management (36). Thus, providers should still utilize these options to support abstinence or reductions in cannabis use.

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Clinical Recommendations

Treatment providers should not ignore marijuana use in their PTSD patients. The VA/DoD PTSD Clinical Practice Guideline (2017) recommends providing evidence-based treatments for the individual disorders concurrently and strongly recommends against treating PTSD with cannabis or cannabis derivatives due to the lack of evidence for their efficacy, known adverse side effects and associated risks (37). PTSD providers should offer education about problems associated with long-term cannabis use and make a referral to a substance use disorder (SUD) specialist for patients experiencing cannabis-related problems if they do not feel they have expertise in treating substance use disorders.

Individuals with comorbid PTSD and SUD do not need to wait for a period of abstinence before addressing their PTSD. A growing number of studies demonstrate that these patients can tolerate trauma-focused treatment and that these treatments do not worsen substance use outcomes. Therefore, providers have a range of options to help improve the lives of patients with the co-occurring disorders. For more information, see Treatment of Co-Occurring PTSD and Substance Use Disorder in VA.

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References

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  37. Department of Veterans Affairs and Department of Defense. (2017). VA/DOD Clinical Practice Guideline for the Management of Posttraumatic Stress Disorder and Acute Stress Disorder. Washington DC: Author. Retrieved from: https://www.healthquality.va.gov/guidelines/MH/ptsd/

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